COX4I2-Related Pancreatic Insufficiency-Anemia-Hyperostosis Syndrome

Mendelian MONDO:0012992 Pathograph 28 Show in embeddings browser Mitochondrial Disease Inborn Error of Metabolism

COX4I2-related pancreatic insufficiency-anemia-hyperostosis syndrome (EPIDACH, also called Shteyer syndrome) is a rare autosomal recessive multisystem disorder described with homozygous c.412G>A (p.Glu138Lys) in five affected relatives from two consanguineous families. Exocrine pancreatic insufficiency with pancreatic atrophy and fatty replacement, early dyserythropoietic anemia, and variable calvarial hyperostosis are characteristic. Hypotonia, developmental delay and respiratory symptoms also occur. Patient fibroblasts show reduced COX4I2 transcript and attenuated induction by cobalt chloride, but normal measured cytochrome c oxidase activity. The molecular steps connecting this regulatory/structural complex IV subunit to pancreatic, erythroid and skeletal disease remain incompletely demonstrated.

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7
Pathophys.
25
Phenotypes
28
Pathograph
1
Genes
1
Variants
6
Medical Actions
1
Datasets
4
Models
7
References
1
Deep Research
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Classifications

Harrison's Part
ENDOCRINOLOGY METABOLISM GENETICS ENVIRONMENT DISEASE
Mechanistic Nosology
mitochondrial disease
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Pathophysiology

7
Reduced COX4I2 Transcript Abundance
Fibroblasts carrying homozygous E138K have approximately one quarter of control COX4I2 mRNA under baseline culture conditions. The mechanism of transcript reduction is unresolved; the coding missense change is not established to alter splicing, promoter activity or protein stability.
COX4I2 hgnc:16232 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves COX4I2 (hgnc:16232). hgnc:16232 is a gene from the HUGO Gene Nomenclature Committee.
Experimental models
E138K patient fibroblast cultures PRIMARY CELL CULTURE
Downstream
Proposed Tissue-Specific Complex IV Dysfunction Reduced availability of the regulatory/structural isoform could alter complex IV function in susceptible tissues; normal fibroblast enzymology prevents assuming a universal deficit.
Show evidence (2 references)
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT In Vitro
"expression in the patients' cells is reduced to 25% of the control in normoxic conditions"
Real-time PCR measured reduced COX4I2 mRNA in cultured patient fibroblasts, not absent protein.
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"changing glutamic acid at codon 138 to lysine (E138K)"
The primary report identifies the homozygous missense allele; reduced transcript does not establish a splice or promoter mechanism.
Attenuated Hypoxia-Mimetic Transcript Induction
Patient fibroblasts respond poorly to 100 micromolar cobalt chloride for 48 hours: COX4I2 mRNA rises less than threefold compared with approximately 25-fold in controls. This chemical challenge supports abnormal inducibility without directly testing physiological tissue hypoxia.
COX4I2 hgnc:16232 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves COX4I2 (hgnc:16232). hgnc:16232 is a gene from the HUGO Gene Nomenclature Committee.
response to hypoxia GO:0001666 ↓ DECREASED Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased response to hypoxia (GO:0001666). GO:0001666 is a biological process from the Gene Ontology.
Experimental models
E138K patient fibroblast cultures PRIMARY CELL CULTURE
Downstream
Proposed Tissue-Specific Complex IV Dysfunction An attenuated expression response may limit adaptation under stress; the affected-organ consequences were not measured.
Show evidence (1 reference)
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT In Vitro
"expression increased 25-fold, whereas in patients' cells COX4I2 mRNA level increased by less than 3-fold over the level in normoxic conditions."
The comparison used cobalt chloride for 48 hours; this is chemical hypoxia mimicry rather than a low-oxygen exposure.
Proposed Tissue-Specific Complex IV Dysfunction
Mechanism confidence: Hypothetical
Altered COX4I2 expression or function is proposed to impair complex IV-dependent metabolism in selected tissues. Patient pancreatic and erythroid enzymology, holoenzyme assembly and ATP production were not demonstrated. Control pancreas/islet RNA ratios motivate tissue selectivity, while normal patient fibroblast COX activity and the differences between mouse knockout and human disease constrain the model.
COX4I2 hgnc:16232 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves COX4I2 (hgnc:16232). hgnc:16232 is a gene from the HUGO Gene Nomenclature Committee.
mitochondrial electron transport, cytochrome c to oxygen GO:0006123 ↓ DECREASED Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased mitochondrial electron transport, cytochrome c to oxygen (GO:0006123). GO:0006123 is a biological process from the Gene Ontology.
cytochrome-c oxidase activity (holoenzyme activity to which the COX4I2 subunit contributes) GO:0004129 ↓ DECREASED Gene Ontology (GO) Relation: this pathophysiological event involves this molecular function This pathophysiological event involves decreased cytochrome-c oxidase activity (holoenzyme activity to which the COX4I2 subunit contributes), annotated with cytochrome-c oxidase activity (GO:0004129). GO:0004129 is a molecular function from the Gene Ontology.
Experimental models
E138K patient fibroblast cultures PRIMARY CELL CULTURE
COX4 isoform replacement in HEK293 cells CELL LINE
Downstream
Pancreatic Parenchymal Loss A tissue-specific metabolic defect is a proposed cause of pancreatic degeneration; intervening injury pathways are unknown.
Disordered Erythropoiesis The disease association links COX4I2 to erythroid pathology, but the cell-autonomous metabolic mechanism has not been established.
Proposed Impaired Calvarial Bone Resorption The original report proposes altered osteoclast function as an explanation for skull thickening.
Show evidence (2 references)
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT INDIRECT In Vitro
"the acinar cells are the major source of COX4I2 mRNA in the pancreas, whereas COX4I1 is the predominant isoform in the islet cells."
The conclusion is inferred from whole-pancreas versus islet RNA. It does not show COX4I2 exceeds COX4I1 in purified acinar cells.
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT In Vitro
"the normal COX activity in the patients' skin fibroblasts (data not shown)"
Normal fibroblast enzymology limits claims of universal complex IV deficiency and does not exclude tissue-specific dysfunction.
Pancreatic Parenchymal Loss
CT demonstrates pancreatic atrophy and extensive fatty replacement. Functional loss can be severe, with fecal elastase of 20 micrograms/g in the index patients. One additional affected relative had this structural lesion despite normal stool consistency; pancreatic endocrine dysfunction was not established.
pancreatic acinar cell CL:0002064 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves pancreatic acinar cell (CL:0002064). CL:0002064 is a cell type from the Cell Ontology.
Animal models
Cox4i2-knockout mouse Mouse fails to recapitulate
Downstream
Exocrine pancreatic insufficiency Loss of exocrine tissue accompanies markedly reduced digestive enzyme output.
Pancreatic atrophy Loss of pancreatic parenchyma appears as atrophy on imaging.
Intestinal Fat Malabsorption Reduced pancreatic enzyme delivery impairs digestion and absorption of dietary fat.
Show evidence (2 references)
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"The abdominal CT scan disclosed pancreatic atrophy with massive fatty infiltration and increased hepatic density"
Patient imaging demonstrates loss and fatty replacement of pancreatic tissue.
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"Stool elastase was invariably low (20 μg/g of stool, normal 200–500 μg/g of stool)."
Very low fecal elastase directly supports exocrine insufficiency in the four index patients.
Intestinal Fat Malabsorption
Reduced pancreatic digestive capacity produces steatorrhea, inadequate nutrient absorption and fat-soluble vitamin depletion. Pancreatic enzyme and vitamin replacement improve stool quality and growth; hematologic disease requires separate management.
Downstream
Steatorrhea Undigested dietary fat contributes to fatty stools.
Malabsorption Exocrine dysfunction causes malabsorption of fat-soluble nutrients.
Failure to thrive Poor nutrient absorption contributes to early growth failure; growth can improve with enzyme treatment.
Decreased circulating vitamin E Vitamin E was low when enzyme replacement was withdrawn.
Coagulation abnormality Impaired coagulation accompanied vitamin malabsorption off enzymes; specific factor assays were not reported.
Show evidence (3 references)
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"Soon after birth, they presented with steatorrhea, failure to thrive, and anemia."
The brothers presented in early infancy with malabsorption and growth failure.
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"While patients were off pancreatic enzymes, vitamin E was low, and coagulation functions were impaired."
Vitamin E depletion and impaired coagulation occurred off enzyme replacement.
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"They had nearly no weight gain over their birth weight until 4–6 months of age, when supplementation with pancreatic enzymes began."
Enzyme replacement was followed by improvement in steatorrhea and later growth catch-up.
Disordered Erythropoiesis
The marrow shows erythroid hyperplasia with megaloblastic and multinucleated precursors, consistent with ineffective erythropoiesis. Severe early anemia often requires repeated transfusions. Splenic sequestration or red-cell destruction may contribute, but red-cell survival was not measured in these patients.
Downstream
Anemia Abnormal erythroid maturation contributes to anemia; the relative contribution of peripheral destruction remains uncertain.
Erythroid dysplasia Megaloblastic and multinucleated precursors document abnormal erythroid maturation.
Erythroid hyperplasia The marrow expands its erythroid compartment despite anemia.
Show evidence (2 references)
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"There was erythroid hyperplasia with megaloblastic change and bi- and multi-nucleated red cell precursors but no internuclear chromatin bridges"
Bone marrow in one affected boy demonstrates erythroid dysplasia and hyperplasia.
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"The hemoglobin levels were normal at birth but dropped to 5–9 g/100 ml at one month, and RBC transfusions were thereafter required at 6–8 week intervals."
The three brothers developed severe anemia during the first month.
Proposed Impaired Calvarial Bone Resorption
Mechanism confidence: Hypothetical
The founding report hypothesizes that COX4I2-dependent osteoclast function could affect calvarial resorption. COX4I2 predominance in calvarial osteoclasts and a functional resorption defect were not measured. This proposed link should not be generalized to osteopetrosis, which was absent in the reported skeletal imaging.
Downstream
Calvarial hyperostosis Reduced resorption is a proposed explanation for parietal thickening, not an experimentally established intermediate.
Show evidence (1 reference)
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT INDIRECT Human Clinical
"it is tempting to speculate that the underlying mechanism of calvarial hyperostosis in our patients is due to COX4I2's being the predominant COX4 isoform in calvarial osteoclasts."
This is the authors’ proposed mechanism; neither osteoclast isoform predominance nor patient bone-resorption failure was measured.
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Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.
Pathograph: causal mechanism network for COX4I2-Related Pancreatic Insufficiency-Anemia-Hyperostosis Syndrome Interactive directed graph showing how pathophysiology mechanisms, phenotypes, genetic factors and variants, experimental models, environmental triggers, and treatments relate through causal and linked edges.
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Phenotypes

25
Blood 5
Anemia HP:0001903 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Anemia (HP:0001903). HP:0001903 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"The hemoglobin levels were normal at birth but dropped to 5–9 g/100 ml at one month, and RBC transfusions were thereafter required at 6–8 week intervals."
The three brothers developed severe anemia during the first month.
Erythroid dysplasia HP:0031688 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Erythroid dysplasia (HP:0031688). HP:0031688 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"There was erythroid hyperplasia with megaloblastic change and bi- and multi-nucleated red cell precursors but no internuclear chromatin bridges"
Bone marrow in one affected boy demonstrates erythroid dysplasia and hyperplasia.
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"Iron-laden macrophages were seen, but there were no ring sideroblasts."
The marrow findings distinguish dyserythropoiesis from demonstrated ring-sideroblast anemia.
Erythroid hyperplasia HP:0012132 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Erythroid hyperplasia (HP:0012132). HP:0012132 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"There was erythroid hyperplasia with megaloblastic change and bi- and multi-nucleated red cell precursors but no internuclear chromatin bridges"
Bone marrow in one affected boy demonstrates erythroid dysplasia and hyperplasia.
Anisopoikilocytosis HP:0004823 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Anisopoikilocytosis (HP:0004823). HP:0004823 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"Blood smears of all four patients showed moderate anisocytosis and poikilocytosis, mild polychromesia and basophilic stippling, and few normoblasts."
Peripheral smears directly document the red-cell morphology.
Coagulation abnormality Abnormality of coagulation HP:0001928 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Coagulation abnormality, annotated with Abnormality of coagulation (HP:0001928). HP:0001928 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"While patients were off pancreatic enzymes, vitamin E was low, and coagulation functions were impaired."
Vitamin E depletion and impaired coagulation occurred off enzyme replacement.
Cardiovascular 1
Splenomegaly HP:0001744 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Splenomegaly (HP:0001744). HP:0001744 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"transfusion frequency increased in patient 1989 concomitantly with the development of massive splenomegaly."
The oldest brother developed marked splenic enlargement.
Digestive 7
Exocrine pancreatic insufficiency HP:0001738 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Exocrine pancreatic insufficiency (HP:0001738). HP:0001738 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"Stool elastase was invariably low (20 μg/g of stool, normal 200–500 μg/g of stool)."
Very low fecal elastase directly supports exocrine insufficiency in the four index patients.
Pancreatic atrophy HP:6000156 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Pancreatic atrophy (HP:6000156). HP:6000156 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"The abdominal CT scan disclosed pancreatic atrophy with massive fatty infiltration and increased hepatic density"
Patient imaging demonstrates loss and fatty replacement of pancreatic tissue.
Steatorrhea HP:0002570 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Steatorrhea (HP:0002570). HP:0002570 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"Soon after birth, they presented with steatorrhea, failure to thrive, and anemia."
The brothers presented in early infancy with malabsorption and growth failure.
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"Her stools normalized, and within four months she gained 2 Kg, added 6 cm to her height, turned more agile, and spoke in short sentences."
The index girl improved after pancreatic enzymes and fat-soluble vitamins.
Malabsorption HP:0002024 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Malabsorption (HP:0002024). HP:0002024 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"While patients were off pancreatic enzymes, vitamin E was low, and coagulation functions were impaired."
Vitamin E depletion and impaired coagulation occurred off enzyme replacement.
Hepatomegaly HP:0002240 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Hepatomegaly (HP:0002240). HP:0002240 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"abdominal ultrasound revealed enlarged homogeneous liver with normal bile ducts and portal flow, splenomegaly, and a thickened, granular pancreas."
Ultrasound establishes liver and splenic enlargement.
Inguinal hernia HP:0000023 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Inguinal hernia (HP:0000023). HP:0000023 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"inguinal and umbilical hernia, and generalized muscle hypotonia"
The physical examination describes both hernia locations.
Umbilical hernia HP:0001537 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Umbilical hernia (HP:0001537). HP:0001537 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"inguinal and umbilical hernia, and generalized muscle hypotonia"
The physical examination describes both hernia locations.
Head and Neck 2
Calvarial hyperostosis Cranial hyperostosis HP:0004437 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Calvarial hyperostosis, annotated with Cranial hyperostosis (HP:0004437). HP:0004437 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"Skull x-rays of family A patients revealed abnormally thickened parietal bones"
The primary radiographs establish calvarial hyperostosis in the three brothers.
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"Nonetheless, she had neither skull hyperostosis nor skin rash."
The index girl demonstrates variability of the named triad.
Carious teeth HP:0000670 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Carious teeth (HP:0000670). HP:0000670 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"bronchial asthma, maldentition, and severe dental carries."
The source reports severe caries, with its original spelling preserved in the quotation.
Immune 1
Asthma HP:0002099 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Asthma (HP:0002099). HP:0002099 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"Since early infancy she suffered from allergic rhinitis and severe asthma and was easily fatigued."
The fifth relative had clinically reported respiratory symptoms.
Integument 1
Skin hyperpigmentation Hyperpigmentation of the skin HP:0000953 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Skin hyperpigmentation, annotated with Hyperpigmentation of the skin (HP:0000953). HP:0000953 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"scaly skin rash over the perineum and 0.2–0.5 cm hyperpigmented lesions"
The report documents the pigment lesions and rash in the brothers.
Metabolism 3
Unconjugated hyperbilirubinemia HP:0008282 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Unconjugated hyperbilirubinemia (HP:0008282). HP:0008282 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"The parents noted several episodes of yellowish sclera associated with mild indirect hyperbilirubinemia."
The report specifies indirect bilirubin elevation.
Elevated hepatic transaminases Elevated circulating hepatic transaminase concentration HP:0002910 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Elevated hepatic transaminases, annotated with Elevated circulating hepatic transaminase concentration (HP:0002910). HP:0002910 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"Serum transaminases, LDH, and bilirubin were slightly elevated"
The report records mild elevations, without establishing progressive liver disease.
Decreased circulating vitamin E Decreased circulating vitamin E concentration HP:0100513 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Decreased circulating vitamin E, annotated with Decreased circulating vitamin E concentration (HP:0100513). HP:0100513 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"While patients were off pancreatic enzymes, vitamin E was low, and coagulation functions were impaired."
Vitamin E depletion and impaired coagulation occurred off enzyme replacement.
Musculoskeletal 3
Osteopenia HP:0000938 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Osteopenia (HP:0000938). HP:0000938 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"In a skeletal survey, delayed bone age and osteopenia were seen."
Generalized bone findings coexist with calvarial hyperostosis.
Delayed skeletal maturation HP:0002750 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Delayed skeletal maturation (HP:0002750). HP:0002750 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"In a skeletal survey, delayed bone age and osteopenia were seen."
Radiographs establish delayed bone age.
Generalized hypotonia HP:0001290 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Generalized hypotonia (HP:0001290). HP:0001290 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"generalized muscle hypotonia with delayed psychomotor development at around 2 years of age but near-normal development after 4 years of age."
Hypotonia and developmental delay were observed; the syndrome is not exclusively non-neurological.
Nervous System 1
Global developmental delay HP:0001263 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Global developmental delay (HP:0001263). HP:0001263 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"generalized muscle hypotonia with delayed psychomotor development at around 2 years of age but near-normal development after 4 years of age."
Hypotonia and developmental delay were observed; the syndrome is not exclusively non-neurological.
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"Her development was delayed: she started walking at 30 months, and when we first saw her, at 3 years old, she had only 10 words."
Both motor and language development were delayed in the index girl.
Growth 1
Failure to thrive HP:0001508 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Failure to thrive (HP:0001508). HP:0001508 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"Soon after birth, they presented with steatorrhea, failure to thrive, and anemia."
The brothers presented in early infancy with malabsorption and growth failure.
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"They had nearly no weight gain over their birth weight until 4–6 months of age, when supplementation with pancreatic enzymes began."
Enzyme replacement was followed by improvement in steatorrhea and later growth catch-up.
🧬

Genetic Associations

1
COX4I2 E138K-associated EPIDACH
Gene: COX4I2 hgnc:16232 gene page HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is COX4I2 (hgnc:16232). hgnc:16232 is a gene from the HUGO Gene Nomenclature Committee. relationship_type: CAUSATIVE variant_origin: GERMLINE
Autosomal recessive
Show evidence (3 references)
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"changing glutamic acid at codon 138 to lysine (E138K)"
The primary report identifies the homozygous missense allele; reduced transcript does not establish a splice or promoter mechanism.
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"The four patients were homozygous for the mutation, and their unaffected relatives were heterozygotes or normal homozygotes"
Segregation in the index families supports recessive inheritance.
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"None of them carried the mutation."
The 90 ethnically matched and 90 Ashkenazi-Jewish controls screened in the study lacked E138K; this does not estimate prevalence.
Variants (1)
c.412G>A (p.Glu138Lys)
Gene: COX4I2 hgnc:16232 HUGO Gene Nomenclature Committee (hgnc) Relation: this variant is in this gene This variant is in COX4I2 (hgnc:16232). hgnc:16232 is a gene from the HUGO Gene Nomenclature Committee. single nucleotide variant
Homozygous coding missense substitution, also described as E138K. The association is supported by segregation and altered transcript abundance/inducibility in patient cells. These assays do not establish a splicing mechanism or eliminate all alternative explanations.
Show evidence (4 references)
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"changing glutamic acid at codon 138 to lysine (E138K)"
The primary report identifies the homozygous missense allele; reduced transcript does not establish a splice or promoter mechanism.
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"The four patients were homozygous for the mutation, and their unaffected relatives were heterozygotes or normal homozygotes"
Segregation in the index families supports recessive inheritance.
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT In Vitro
"expression in the patients' cells is reduced to 25% of the control in normoxic conditions"
Real-time PCR measured reduced COX4I2 mRNA in cultured patient fibroblasts, not absent protein.
+ 1 more reference
💊

Medical Actions

6
Pancreatic enzyme replacement
Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Agent: Pancrelipase NCIT:C29345 NCI Thesaurus (NCIT) Relation: this treatment uses this therapeutic agent This treatment uses Pancrelipase (NCIT:C29345). NCIT:C29345 is a therapeutic agent from the NCI Thesaurus.
Oral pancreatic enzymes improved stool quality and growth in reported patients. Replacement treats exocrine insufficiency but did not reduce transfusion frequency; it is not a correction of the molecular defect.
Target Phenotypes: Exocrine pancreatic insufficiency HP:0001738 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Exocrine pancreatic insufficiency (HP:0001738). HP:0001738 is a phenotype from the Human Phenotype Ontology. Steatorrhea HP:0002570 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Steatorrhea (HP:0002570). HP:0002570 is a phenotype from the Human Phenotype Ontology. Failure to thrive HP:0001508 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Failure to thrive (HP:0001508). HP:0001508 is a phenotype from the Human Phenotype Ontology.
Show evidence (3 references)
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"They had nearly no weight gain over their birth weight until 4–6 months of age, when supplementation with pancreatic enzymes began."
Enzyme replacement was followed by improvement in steatorrhea and later growth catch-up.
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"Transfusion frequency was not influenced by the administration of pancreatic enzymes."
Pancreatic treatment did not resolve the hematologic disease.
DOI:10.3389/fped.2022.909925 SUPPORT REVIEW SYNTHESIS Other
"The disease management is mainly based on the symptomatic treatment of EPI (pancreatic enzyme and liposoluble vitamins supplementation) and iterative transfusions for anemia."
The Shteyer syndrome section summarizes supportive management.
Fat-soluble vitamin supplementation
Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Agent: vitamin E CHEBI:33234 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses vitamin E (CHEBI:33234). CHEBI:33234 is a therapeutic agent from Chemical Entities of Biological Interest.
Platform: Small molecule
Replace and monitor fat-soluble vitamins in the context of malabsorption. Enzymes and vitamins were given together in the index girl; vitamin E and coagulation deteriorated off enzyme replacement.
Target Phenotypes: Malabsorption HP:0002024 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Malabsorption (HP:0002024). HP:0002024 is a phenotype from the Human Phenotype Ontology. Decreased circulating vitamin E HP:0100513 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Decreased circulating vitamin E, annotated with Decreased circulating vitamin E concentration (HP:0100513). HP:0100513 is a phenotype from the Human Phenotype Ontology. Coagulation abnormality HP:0001928 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Coagulation abnormality, annotated with Abnormality of coagulation (HP:0001928). HP:0001928 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"Supplementation with pancreatic enzymes, along with fat-soluble vitamins, was then added."
This is direct disease-specific treatment use.
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"While patients were off pancreatic enzymes, vitamin E was low, and coagulation functions were impaired."
Vitamin E depletion and impaired coagulation occurred off enzyme replacement.
Red-cell transfusion support
Action: Blood TransfusionNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Blood Transfusion (NCIT:C15192). NCIT:C15192 is a clinical intervention from the NCI Thesaurus. NCIT:C15192
Severe infantile anemia required repeated red-cell transfusions, with frequency changing over time. Hematology follow-up should individualize support and monitor complications of chronic transfusion.
Target Phenotypes: Anemia HP:0001903 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Anemia (HP:0001903). HP:0001903 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"The hemoglobin levels were normal at birth but dropped to 5–9 g/100 ml at one month, and RBC transfusions were thereafter required at 6–8 week intervals."
The three brothers developed severe anemia during the first month.
Splenectomy in selected severe hematologic disease
Action: SplenectomyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Splenectomy (NCIT:C15328). NCIT:C15328 is a clinical intervention from the NCI Thesaurus. NCIT:C15328
One affected girl stopped requiring transfusions after splenectomy at five years, with hemoglobin stabilizing at 9–10 g/dL. This single uncontrolled observation does not establish routine use or comparative efficacy; any consideration requires specialist assessment of the risks and alternatives.
Target Phenotypes: Anemia HP:0001903 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Anemia (HP:0001903). HP:0001903 is a phenotype from the Human Phenotype Ontology. Splenomegaly HP:0001744 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Splenomegaly (HP:0001744). HP:0001744 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"At 3 years hepatosplenomegaly became evident, and she underwent splenectomy at 5 years. Thereafter, she no longer required blood transfusions, and her hemoglobin level stabilized at 9–10 g/100 ml."
The report describes one postsplenectomy outcome, not a trial.
Multidisciplinary follow-up
Action: Supportive CareNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Supportive Care (NCIT:C15747). NCIT:C15747 is a clinical intervention from the NCI Thesaurus. NCIT:C15747
Follow nutritional status, growth, hematologic course, development, dental health and respiratory symptoms according to the individual findings. The clinical literature is too limited to define syndrome-specific surveillance intervals or a disease-modifying treatment.
Show evidence (3 references)
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"generalized muscle hypotonia with delayed psychomotor development at around 2 years of age but near-normal development after 4 years of age."
Hypotonia and developmental delay were observed; the syndrome is not exclusively non-neurological.
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"While patients were off pancreatic enzymes, vitamin E was low, and coagulation functions were impaired."
Vitamin E depletion and impaired coagulation occurred off enzyme replacement.
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"bronchial asthma, maldentition, and severe dental carries."
Reported multisystem findings motivate individualized supportive follow-up.
Genetic counseling
Action: Genetic CounselingNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Genetic Counseling (NCIT:C15240). NCIT:C15240 is a clinical intervention from the NCI Thesaurus. NCIT:C15240
Explain the recessive segregation reported in the families and the limited variant and prognosis evidence. When both parents carry a causative allele, standard Mendelian counseling gives a 25% affected risk per pregnancy. Recurrence assessment and reproductive testing depend on an adequately established familial diagnosis.
Show evidence (1 reference)
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"The four patients were homozygous for the mutation, and their unaffected relatives were heterozygotes or normal homozygotes"
Segregation in the index families supports recessive inheritance.
🔬

Diagnosis

6
COX4I2 sequencing and family segregation
Investigate the combination of exocrine insufficiency, dyserythropoietic anemia and variable skull changes with molecular testing and segregation analysis. A phenotype-based multigene approach can address overlapping syndromes; isolated heterozygosity or a variant of uncertain significance does not establish this diagnosis.
Genetic Testing NCIT:C15709 NCI Thesaurus (NCIT)
Show evidence (2 references)
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"changing glutamic acid at codon 138 to lysine (E138K)"
The primary report identifies the homozygous missense allele; reduced transcript does not establish a splice or promoter mechanism.
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"The four patients were homozygous for the mutation, and their unaffected relatives were heterozygotes or normal homozygotes"
Segregation in the index families supports recessive inheritance.
Fecal elastase and nutritional evaluation
Assess pancreatic enzyme output, growth and fat-soluble vitamin status. Low fecal elastase can establish exocrine dysfunction; the absence of steatorrhea does not exclude structural pancreatic disease.
Fecal elastase and nutritional evaluation
Show evidence (3 references)
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"Stool elastase was invariably low (20 μg/g of stool, normal 200–500 μg/g of stool)."
Very low fecal elastase directly supports exocrine insufficiency in the four index patients.
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"While patients were off pancreatic enzymes, vitamin E was low, and coagulation functions were impaired."
Vitamin E depletion and impaired coagulation occurred off enzyme replacement.
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"her stools were always of normal consistency"
The fifth affected relative had normal stool consistency despite atrophic fatty pancreas.
Pancreatic imaging
Ultrasound and cross-sectional imaging can document pancreatic structure and hepatosplenomegaly. The primary CT study demonstrated pancreatic atrophy with fatty replacement; modality and follow-up should be individualized.
Computed Tomography NCIT:C17204 NCI Thesaurus (NCIT)
Show evidence (1 reference)
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"The abdominal CT scan disclosed pancreatic atrophy with massive fatty infiltration and increased hepatic density"
Patient imaging demonstrates loss and fatty replacement of pancreatic tissue.
Blood count, smear and marrow assessment
Characterize anemia, red-cell morphology and transfusion requirements. Marrow examination in a reported child showed erythroid hyperplasia and dysplasia without ring sideroblasts. Other marrow lineages were preserved in the index patients.
Bone Marrow Biopsy NCIT:C15193 NCI Thesaurus (NCIT)
Show evidence (2 references)
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"There was erythroid hyperplasia with megaloblastic change and bi- and multi-nucleated red cell precursors but no internuclear chromatin bridges"
Bone marrow in one affected boy demonstrates erythroid dysplasia and hyperplasia.
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"Iron-laden macrophages were seen, but there were no ring sideroblasts."
The absence of ring sideroblasts is a diagnostic distinction from Pearson-like presentations.
Skeletal assessment
Skull radiographs identify parietal hyperostosis, which is variable. Bone age and generalized mineralization also require attention; localized skull thickening does not imply generalized osteopetrosis.
Skeletal assessment
Show evidence (2 references)
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"Skull x-rays of family A patients revealed abnormally thickened parietal bones"
The primary radiographs establish calvarial hyperostosis in the three brothers.
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"In a skeletal survey, delayed bone age and osteopenia were seen."
Survey findings extend beyond the skull.
Interpretation of respiratory-chain screening
Normal plasma lactate and normal fibroblast COX activity occurred in the founding families and cannot exclude the syndrome. Consider cystic fibrosis, Shwachman-Diamond syndrome, Pearson syndrome and Johanson-Blizzard syndrome according to the phenotype and molecular findings.
Interpretation of respiratory-chain screening
Show evidence (2 references)
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Human Clinical
"Plasma lactate levels were always normal"
The primary series had normal circulating lactate.
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT In Vitro
"the normal COX activity in the patients' skin fibroblasts (data not shown)"
Normal fibroblast enzymology limits claims of universal complex IV deficiency and does not exclude tissue-specific dysfunction.
📊

Related Datasets

1
Expression Proflies of Human Normal tissues geo:GDS1096
Normal human tissue expression atlas used in the founding report to prioritize COX4I2 through a bone-marrow expression profile (probe 212312_at). It is a background expression resource, not a dataset of EPIDACH patients.
MICROARRAY
The repository describes expression profiling across 36 normal human tissue types using pooled donor RNA. Tissue expression does not establish disease causality or a patient-specific expression defect.
Show evidence (1 reference)
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT Computational
"this gene was highly expressed in bone marrow (GEO profiles: GDS1096/212312_at /COX4I2)."
The original report explicitly identifies the accession and probe used for candidate prioritization.
🧫

Experimental Models

3
E138K patient fibroblast cultures PRIMARY_CELL_CULTURE
Real-time PCR under baseline conditions and after cobalt chloride exposure demonstrates reduced transcript abundance and inducibility. COX activity was normal; these cells do not directly assay pancreas, erythroid precursors or osteoclasts.
fibroblast CL:0000057 Cell Ontology (CL) Relation: this experimental model uses this cell type This experimental model uses fibroblast (CL:0000057). CL:0000057 is a cell type from the Cell Ontology.
Cell source
Skin fibroblasts from patients with homozygous COX4I2 E138K and control fibroblasts
Publication
PMID:19268275
Pathograph links
Reduced COX4I2 Transcript Abundance recapitulates observes: molecular
Limitations: Findings are from cultured skin fibroblasts.
Attenuated Hypoxia-Mimetic Transcript Induction recapitulates observes: molecular
Limitations: Cobalt chloride mimics aspects of hypoxia; actual low-oxygen tissue physiology was not tested.
Proposed Tissue-Specific Complex IV Dysfunction fails to recapitulate observes: molecular
Limitations: Normal fibroblast COX activity does not reproduce a generalized enzymatic deficit.
Show evidence (1 reference)
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT In Vitro
"the normal COX activity in the patients' skin fibroblasts (data not shown)"
Normal fibroblast enzymology limits claims of universal complex IV deficiency and does not exclude tissue-specific dysfunction.
Show evidence (3 references)
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT In Vitro
"expression in the patients' cells is reduced to 25% of the control in normoxic conditions"
Real-time PCR measured reduced COX4I2 mRNA in cultured patient fibroblasts, not absent protein.
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT In Vitro
"expression increased 25-fold, whereas in patients' cells COX4I2 mRNA level increased by less than 3-fold over the level in normoxic conditions."
The comparison used cobalt chloride for 48 hours; this is chemical hypoxia mimicry rather than a low-oxygen exposure.
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/ SUPPORT In Vitro
"the normal COX activity in the patients' skin fibroblasts (data not shown)"
Normal fibroblast enzymology limits claims of universal complex IV deficiency and does not exclude tissue-specific dysfunction.
COX4 isoform replacement in HEK293 cells CELL_LINE
Either wild-type isoform restores similar COX assembly, activity and respiratory capacity. COX4I2-containing enzyme has lower oxygen affinity, with higher p50, and lower normoxic ROS. This tests isoform biology rather than the patient E138K allele.
Cell source
HEK293 cells with CRISPR double knockout of COX4I1/COX4I2 and separate isoform-specific knock-in
Publication
PMID:32075102
Pathograph links
Proposed Tissue-Specific Complex IV Dysfunction partially recapitulates observes: molecular
Limitations: A double knockout and wild-type replacement in transformed cells do not establish an E138K defect in human pancreas or marrow.
Show evidence (2 references)
PMID:32075102 SUPPORT In Vitro
"The content, composition, and incorporation of COX into supercomplexes were comparable in COX4i1- and COX4i2-expressing cells."
Isoform substitution does not itself imply defective assembly.
PMID:32075102 SUPPORT In Vitro
"The p50 (partial pressure of oxygen at half-maximal respiration) was increased twofold in COX4i2 versus COX4i1 cells, indicating decreased oxygen affinity of the COX4i2-containing enzyme."
Higher p50 means lower, not higher, oxygen affinity.
COX4I2 perturbation in pulmonary arterial smooth muscle cells PRIMARY_CELL_CULTURE
KO mouse PASMCs lack hypoxia-induced superoxide and calcium increases and show attenuated membrane depolarization. Re-expression of Cox4i2 and hydrogen peroxide supplementation interrogate different steps of signaling. Human siRNA experiments support a role in hypoxic depolarization. No EPIDACH patient lung cells were tested.
Cell source
PASMCs isolated from wild-type or Cox4i2-knockout mice, and human PASMCs treated with COX4I2 siRNA
Publication
PMID:28620066
Knockout lung and PASMC findings are not direct proof of the mechanism underlying asthma in affected patients. Chronic hypoxia responses differ from acute oxygen sensing.
Show evidence (2 references)
PMID:28620066 SUPPORT In Vitro
"pulmonary arterial smooth muscle cells (PASMCs) from Cox4i2-/- mice showed no hypoxia-induced increase of intracellular calcium."
Isolated mouse-cell assays define a signaling phenotype, not a human clinical manifestation.
PMID:28620066 SUPPORT In Vitro
"Downregulation of Cox4i2 by siRNA (Online Figure XC) decreased the hypoxia-induced depolarization in human PASMCs (Figure 5)."
Human cell knockdown supports a conserved signaling role without testing patient alleles.
🐁

Animal Models

1
Cox4i2-knockout mouse
Whole-animal knockout produces age-dependent lung pathology and reduced methacholine airway responsiveness. Lung tissue COX activity and ATP are reduced, whereas the pancreas lacks the structural pathology seen in human EPIDACH. Acute pulmonary oxygen sensing is defective; chronic hypoxia-induced pulmonary hypertension remains largely intact.
Species
Mouse
Genotype
Cox4i2-/-
Publication
PMID:22730437
Pathograph links
Pancreatic Parenchymal Loss fails to recapitulate observes: tissue
Limitations: Mouse pancreatic histology is normal and pancreatic Cox4i2 expression is negligible relative to lung; the knockout does not reproduce the human pancreatic lesion.
Show evidence (1 reference)
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC3425824/ SUPPORT Model Organism
"the pancreas histology was indistinguishable from the wild-type mice and showed no signs of dysfunction"
The animal model explicitly fails to reproduce the pancreatic disease.
Complete gene knockout differs from E138K. The model supports lung isoform physiology; it has not established the human anemia, hyperostosis or pancreatic mechanism.
Show evidence (4 references)
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC3425824/ SUPPORT Model Organism
"the pancreas histology was indistinguishable from the wild-type mice and showed no signs of dysfunction"
The animal model explicitly fails to reproduce the pancreatic disease.
PMID:22730437 SUPPORT Model Organism
"Knockout mice showed decreased airway responsiveness"
Whole-animal challenge testing demonstrates airway hyporeactivity, which is not equivalent to human asthma.
PMID:22730437 SUPPORT Model Organism
"lung COX activity and cellular ATP levels were significantly reduced (-50 and -29%, respectively)."
The measurements are from knockout mouse lung rather than patient pancreas.
+ 1 more reference
{ }

Source YAML

click to show 
name: COX4I2-Related Pancreatic Insufficiency-Anemia-Hyperostosis Syndrome
category: Mendelian
creation_date: '2026-06-21T00:00:00Z'
synonyms:
- EPIDACH
- Exocrine pancreatic insufficiency, dyserythropoietic anemia, and calvarial hyperostosis
- COX4I2-related cytochrome c oxidase deficiency
- Pancreatic insufficiency-anemia-hyperostosis syndrome
- Shteyer syndrome
description: >-
  COX4I2-related pancreatic insufficiency-anemia-hyperostosis syndrome (EPIDACH, also called Shteyer syndrome)
  is a rare autosomal recessive multisystem disorder described with homozygous c.412G>A (p.Glu138Lys) in five
  affected relatives from two consanguineous families. Exocrine pancreatic insufficiency with pancreatic atrophy
  and fatty replacement, early dyserythropoietic anemia, and variable calvarial hyperostosis are characteristic.
  Hypotonia, developmental delay and respiratory symptoms also occur. Patient fibroblasts show reduced COX4I2
  transcript and attenuated induction by cobalt chloride, but normal measured cytochrome c oxidase activity.
  The molecular steps connecting this regulatory/structural complex IV subunit to pancreatic, erythroid and
  skeletal disease remain incompletely demonstrated.
disease_term:
  preferred_term: COX4I2-related exocrine pancreatic insufficiency, dyserythropoietic anemia, and calvarial hyperostosis (EPIDACH)
  term:
    id: MONDO:0012992
    label: pancreatic insufficiency-anemia-hyperostosis syndrome
parents:
- Mitochondrial Disease
- Inborn Error of Metabolism
classifications:
  harrisons_chapter:
  - classification_value: ENDOCRINOLOGY_METABOLISM
    notes: >-
      A Mendelian disorder involving a nuclear-encoded mitochondrial respiratory-chain subunit and multisystem
      metabolic dysfunction.
  - classification_value: GENETICS_ENVIRONMENT_DISEASE
    notes: >-
      The disorder is a monogenic autosomal recessive condition caused by biallelic COX4I2 variants identified
      through homozygosity mapping.
  mechanistic_category:
  - classification_value: mitochondrial disease
references:
- reference: PMID:19268275
  title: >-
    Exocrine pancreatic insufficiency, dyserythropoeitic anemia, and calvarial hyperostosis are caused by a
    mutation in the COX4I2 gene.
- reference: PMID:22730437
  title: >-
    Cytochrome c oxidase subunit 4 isoform 2-knockout mice show reduced enzyme activity, airway hyporeactivity,
    and lung pathology.
- reference: PMID:28620066
  title: Mitochondrial Complex IV Subunit 4 Isoform 2 Is Essential for Acute Pulmonary Oxygen Sensing.
- reference: PMID:32075102
  title: Cytochrome c Oxidase Subunit 4 Isoform Exchange Results in Modulation of Oxygen Affinity.
- reference: DOI:10.3389/fped.2022.909925
  title: Congenital etiologies of exocrine pancreatic insufficiency
  findings:
  - statement: >-
      The review summarizes supportive enzyme/vitamin replacement and transfusions; the primary report supplies
      the fuller five-relative clinical description.
- reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
  title: >-
    Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by a
    Mutation in the COX4I2 Gene - PMC
- reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC3425824/
  title: >-
    Cytochrome c oxidase subunit 4 isoform 2-knockout mice show reduced enzyme activity, airway hyporeactivity,
    and lung pathology - PMC
pathophysiology:
- name: Reduced COX4I2 Transcript Abundance
  description: >-
    Fibroblasts carrying homozygous E138K have approximately one quarter of control COX4I2 mRNA under baseline
    culture conditions. The mechanism of transcript reduction is unresolved; the coding missense change is
    not established to alter splicing, promoter activity or protein stability.
  biological_scale: MOLECULAR
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: expression in the patients' cells is reduced to 25% of the control in normoxic conditions
    explanation: Real-time PCR measured reduced COX4I2 mRNA in cultured patient fibroblasts, not absent protein.
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: changing glutamic acid at codon 138 to lysine (E138K)
    explanation: >-
      The primary report identifies the homozygous missense allele; reduced transcript does not establish a
      splice or promoter mechanism.
  genes:
  - preferred_term: COX4I2
    term:
      id: hgnc:16232
      label: COX4I2
  downstream:
  - target: Proposed Tissue-Specific Complex IV Dysfunction
    description: >-
      Reduced availability of the regulatory/structural isoform could alter complex IV function in susceptible
      tissues; normal fibroblast enzymology prevents assuming a universal deficit.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
- name: Attenuated Hypoxia-Mimetic Transcript Induction
  description: >-
    Patient fibroblasts respond poorly to 100 micromolar cobalt chloride for 48 hours: COX4I2 mRNA rises less
    than threefold compared with approximately 25-fold in controls. This chemical challenge supports abnormal
    inducibility without directly testing physiological tissue hypoxia.
  biological_scale: MOLECULAR
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      expression increased 25-fold, whereas in patients' cells COX4I2 mRNA level increased by less than 3-fold
      over the level in normoxic conditions.
    explanation: >-
      The comparison used cobalt chloride for 48 hours; this is chemical hypoxia mimicry rather than a low-oxygen
      exposure.
  genes:
  - preferred_term: COX4I2
    term:
      id: hgnc:16232
      label: COX4I2
  biological_processes:
  - preferred_term: response to hypoxia
    term:
      id: GO:0001666
      label: response to hypoxia
    modifier: DECREASED
  downstream:
  - target: Proposed Tissue-Specific Complex IV Dysfunction
    description: >-
      An attenuated expression response may limit adaptation under stress; the affected-organ consequences
      were not measured.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
- name: Proposed Tissue-Specific Complex IV Dysfunction
  description: >-
    Altered COX4I2 expression or function is proposed to impair complex IV-dependent metabolism in selected
    tissues. Patient pancreatic and erythroid enzymology, holoenzyme assembly and ATP production were not demonstrated.
    Control pancreas/islet RNA ratios motivate tissue selectivity, while normal patient fibroblast COX activity
    and the differences between mouse knockout and human disease constrain the model.
  biological_scale: MOLECULAR
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      the acinar cells are the major source of COX4I2 mRNA in the pancreas, whereas COX4I1 is the predominant
      isoform in the islet cells.
    explanation: >-
      The conclusion is inferred from whole-pancreas versus islet RNA. It does not show COX4I2 exceeds COX4I1
      in purified acinar cells.
    directness: INDIRECT
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: the normal COX activity in the patients' skin fibroblasts (data not shown)
    explanation: >-
      Normal fibroblast enzymology limits claims of universal complex IV deficiency and does not exclude tissue-specific
      dysfunction.
  mechanism_confidence: HYPOTHETICAL
  genes:
  - preferred_term: COX4I2
    term:
      id: hgnc:16232
      label: COX4I2
  biological_processes:
  - preferred_term: mitochondrial electron transport, cytochrome c to oxygen
    term:
      id: GO:0006123
      label: mitochondrial electron transport, cytochrome c to oxygen
    modifier: DECREASED
  molecular_functions:
  - preferred_term: cytochrome-c oxidase activity (holoenzyme activity to which the COX4I2 subunit contributes)
    term:
      id: GO:0004129
      label: cytochrome-c oxidase activity
    modifier: DECREASED
    description: >-
      COX4I2 is a non-catalytic, nuclear-encoded subunit of Complex IV; the catalytic redox
      centres are in the mtDNA-encoded subunits. This descriptor names the complex-level
      activity COX4I2 contributes to, not an activity of COX4I2 alone.
  downstream:
  - target: Pancreatic Parenchymal Loss
    description: >-
      A tissue-specific metabolic defect is a proposed cause of pancreatic degeneration; intervening injury
      pathways are unknown.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Disordered Erythropoiesis
    description: >-
      The disease association links COX4I2 to erythroid pathology, but the cell-autonomous metabolic mechanism
      has not been established.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Proposed Impaired Calvarial Bone Resorption
    description: The original report proposes altered osteoclast function as an explanation for skull thickening.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
      reference_title: >-
        Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused
        by a Mutation in the COX4I2 Gene - PMC
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        it is tempting to speculate that the underlying mechanism of calvarial hyperostosis in our patients
        is due to COX4I2's being the predominant COX4 isoform in calvarial osteoclasts.
      explanation: >-
        This is the authors’ proposed mechanism; neither osteoclast isoform predominance nor patient bone-resorption
        failure was measured.
      directness: INDIRECT
- name: Pancreatic Parenchymal Loss
  description: >-
    CT demonstrates pancreatic atrophy and extensive fatty replacement. Functional loss can be severe, with
    fecal elastase of 20 micrograms/g in the index patients. One additional affected relative had this structural
    lesion despite normal stool consistency; pancreatic endocrine dysfunction was not established.
  biological_scale: TISSUE
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: The abdominal CT scan disclosed pancreatic atrophy with massive fatty infiltration and increased hepatic density
    explanation: Patient imaging demonstrates loss and fatty replacement of pancreatic tissue.
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Stool elastase was invariably low (20 μg/g of stool, normal 200–500 μg/g of stool).
    explanation: Very low fecal elastase directly supports exocrine insufficiency in the four index patients.
  cell_types:
  - preferred_term: pancreatic acinar cell
    term:
      id: CL:0002064
      label: pancreatic acinar cell
  downstream:
  - target: Exocrine pancreatic insufficiency
    description: Loss of exocrine tissue accompanies markedly reduced digestive enzyme output.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
      reference_title: >-
        Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused
        by a Mutation in the COX4I2 Gene - PMC
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Stool elastase was invariably low (20 μg/g of stool, normal 200–500 μg/g of stool).
      explanation: Very low fecal elastase directly supports exocrine insufficiency in the four index patients.
  - target: Pancreatic atrophy
    description: Loss of pancreatic parenchyma appears as atrophy on imaging.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
      reference_title: >-
        Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused
        by a Mutation in the COX4I2 Gene - PMC
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: The abdominal CT scan disclosed pancreatic atrophy with massive fatty infiltration and increased hepatic density
      explanation: Patient imaging demonstrates loss and fatty replacement of pancreatic tissue.
  - target: Intestinal Fat Malabsorption
    description: Reduced pancreatic enzyme delivery impairs digestion and absorption of dietary fat.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
- name: Intestinal Fat Malabsorption
  description: >-
    Reduced pancreatic digestive capacity produces steatorrhea, inadequate nutrient absorption and fat-soluble
    vitamin depletion. Pancreatic enzyme and vitamin replacement improve stool quality and growth; hematologic
    disease requires separate management.
  biological_scale: TISSUE
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Soon after birth, they presented with steatorrhea, failure to thrive, and anemia.
    explanation: The brothers presented in early infancy with malabsorption and growth failure.
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: While patients were off pancreatic enzymes, vitamin E was low, and coagulation functions were impaired.
    explanation: Vitamin E depletion and impaired coagulation occurred off enzyme replacement.
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      They had nearly no weight gain over their birth weight until 4–6 months of age, when supplementation
      with pancreatic enzymes began.
    explanation: Enzyme replacement was followed by improvement in steatorrhea and later growth catch-up.
  downstream:
  - target: Steatorrhea
    description: Undigested dietary fat contributes to fatty stools.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
      reference_title: >-
        Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused
        by a Mutation in the COX4I2 Gene - PMC
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Soon after birth, they presented with steatorrhea, failure to thrive, and anemia.
      explanation: The brothers presented in early infancy with malabsorption and growth failure.
  - target: Malabsorption
    description: Exocrine dysfunction causes malabsorption of fat-soluble nutrients.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
      reference_title: >-
        Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused
        by a Mutation in the COX4I2 Gene - PMC
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: While patients were off pancreatic enzymes, vitamin E was low, and coagulation functions were impaired.
      explanation: Vitamin E depletion and impaired coagulation occurred off enzyme replacement.
  - target: Failure to thrive
    description: Poor nutrient absorption contributes to early growth failure; growth can improve with enzyme treatment.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
      reference_title: >-
        Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused
        by a Mutation in the COX4I2 Gene - PMC
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        They had nearly no weight gain over their birth weight until 4–6 months of age, when supplementation
        with pancreatic enzymes began.
      explanation: Enzyme replacement was followed by improvement in steatorrhea and later growth catch-up.
  - target: Decreased circulating vitamin E
    description: Vitamin E was low when enzyme replacement was withdrawn.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
      reference_title: >-
        Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused
        by a Mutation in the COX4I2 Gene - PMC
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: While patients were off pancreatic enzymes, vitamin E was low, and coagulation functions were impaired.
      explanation: Vitamin E depletion and impaired coagulation occurred off enzyme replacement.
  - target: Coagulation abnormality
    description: Impaired coagulation accompanied vitamin malabsorption off enzymes; specific factor assays were not reported.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
      reference_title: >-
        Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused
        by a Mutation in the COX4I2 Gene - PMC
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: While patients were off pancreatic enzymes, vitamin E was low, and coagulation functions were impaired.
      explanation: Vitamin E depletion and impaired coagulation occurred off enzyme replacement.
- name: Disordered Erythropoiesis
  description: >-
    The marrow shows erythroid hyperplasia with megaloblastic and multinucleated precursors, consistent with
    ineffective erythropoiesis. Severe early anemia often requires repeated transfusions. Splenic sequestration
    or red-cell destruction may contribute, but red-cell survival was not measured in these patients.
  biological_scale: CELLULAR
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      There was erythroid hyperplasia with megaloblastic change and bi- and multi-nucleated red cell precursors
      but no internuclear chromatin bridges
    explanation: Bone marrow in one affected boy demonstrates erythroid dysplasia and hyperplasia.
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The hemoglobin levels were normal at birth but dropped to 5–9 g/100 ml at one month, and RBC transfusions
      were thereafter required at 6–8 week intervals.
    explanation: The three brothers developed severe anemia during the first month.
  downstream:
  - target: Anemia
    description: >-
      Abnormal erythroid maturation contributes to anemia; the relative contribution of peripheral destruction
      remains uncertain.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
      reference_title: >-
        Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused
        by a Mutation in the COX4I2 Gene - PMC
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        There was erythroid hyperplasia with megaloblastic change and bi- and multi-nucleated red cell precursors
        but no internuclear chromatin bridges
      explanation: Bone marrow in one affected boy demonstrates erythroid dysplasia and hyperplasia.
  - target: Erythroid dysplasia
    description: Megaloblastic and multinucleated precursors document abnormal erythroid maturation.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
      reference_title: >-
        Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused
        by a Mutation in the COX4I2 Gene - PMC
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        There was erythroid hyperplasia with megaloblastic change and bi- and multi-nucleated red cell precursors
        but no internuclear chromatin bridges
      explanation: Bone marrow in one affected boy demonstrates erythroid dysplasia and hyperplasia.
  - target: Erythroid hyperplasia
    description: The marrow expands its erythroid compartment despite anemia.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
      reference_title: >-
        Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused
        by a Mutation in the COX4I2 Gene - PMC
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        There was erythroid hyperplasia with megaloblastic change and bi- and multi-nucleated red cell precursors
        but no internuclear chromatin bridges
      explanation: Bone marrow in one affected boy demonstrates erythroid dysplasia and hyperplasia.
- name: Proposed Impaired Calvarial Bone Resorption
  description: >-
    The founding report hypothesizes that COX4I2-dependent osteoclast function could affect calvarial resorption.
    COX4I2 predominance in calvarial osteoclasts and a functional resorption defect were not measured. This
    proposed link should not be generalized to osteopetrosis, which was absent in the reported skeletal imaging.
  biological_scale: CELLULAR
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      it is tempting to speculate that the underlying mechanism of calvarial hyperostosis in our patients is
      due to COX4I2's being the predominant COX4 isoform in calvarial osteoclasts.
    explanation: >-
      This is the authors’ proposed mechanism; neither osteoclast isoform predominance nor patient bone-resorption
      failure was measured.
    directness: INDIRECT
  mechanism_confidence: HYPOTHETICAL
  downstream:
  - target: Calvarial hyperostosis
    description: >-
      Reduced resorption is a proposed explanation for parietal thickening, not an experimentally established
      intermediate.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
      reference_title: >-
        Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused
        by a Mutation in the COX4I2 Gene - PMC
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        it is tempting to speculate that the underlying mechanism of calvarial hyperostosis in our patients
        is due to COX4I2's being the predominant COX4 isoform in calvarial osteoclasts.
      explanation: >-
        This is the authors’ proposed mechanism; neither osteoclast isoform predominance nor patient bone-resorption
        failure was measured.
      directness: INDIRECT
phenotypes:
- name: Exocrine pancreatic insufficiency
  description: >-
    Severe exocrine dysfunction is present in the index patients. A fifth relative had atrophic fatty pancreas
    without steatorrhea; stool appearance alone is insufficient to exclude pancreatic involvement.
  phenotype_term:
    preferred_term: Exocrine pancreatic insufficiency
    term:
      id: HP:0001738
      label: Exocrine pancreatic insufficiency
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Stool elastase was invariably low (20 μg/g of stool, normal 200–500 μg/g of stool).
    explanation: Very low fecal elastase directly supports exocrine insufficiency in the four index patients.
  category: Gastrointestinal
- name: Pancreatic atrophy
  description: >-
    CT demonstrates pancreatic atrophy with extensive fatty infiltration, including in the additional relative
    with normal stool consistency.
  phenotype_term:
    preferred_term: Pancreatic atrophy
    term:
      id: HP:6000156
      label: Pancreatic atrophy
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: The abdominal CT scan disclosed pancreatic atrophy with massive fatty infiltration and increased hepatic density
    explanation: Patient imaging demonstrates loss and fatty replacement of pancreatic tissue.
  category: Gastrointestinal
- name: Steatorrhea
  description: >-
    Fatty stools began early in the brothers and followed watery diarrhea in the index girl; they improved
    with pancreatic enzymes.
  phenotype_term:
    preferred_term: Steatorrhea
    term:
      id: HP:0002570
      label: Steatorrhea
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Soon after birth, they presented with steatorrhea, failure to thrive, and anemia.
    explanation: The brothers presented in early infancy with malabsorption and growth failure.
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Her stools normalized, and within four months she gained 2 Kg, added 6 cm to her height, turned more
      agile, and spoke in short sentences.
    explanation: The index girl improved after pancreatic enzymes and fat-soluble vitamins.
  category: Gastrointestinal
- name: Malabsorption
  description: >-
    Fat-soluble vitamin malabsorption accompanies exocrine insufficiency. Quantitative evidence includes low
    vitamin E off enzyme replacement.
  phenotype_term:
    preferred_term: Malabsorption
    term:
      id: HP:0002024
      label: Malabsorption
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: While patients were off pancreatic enzymes, vitamin E was low, and coagulation functions were impaired.
    explanation: Vitamin E depletion and impaired coagulation occurred off enzyme replacement.
  category: Gastrointestinal
- name: Failure to thrive
  description: Marked early growth failure improves after enzyme replacement, with delayed catch-up in the brothers.
  phenotype_term:
    preferred_term: Failure to thrive
    term:
      id: HP:0001508
      label: Failure to thrive
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Soon after birth, they presented with steatorrhea, failure to thrive, and anemia.
    explanation: The brothers presented in early infancy with malabsorption and growth failure.
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      They had nearly no weight gain over their birth weight until 4–6 months of age, when supplementation
      with pancreatic enzymes began.
    explanation: Enzyme replacement was followed by improvement in steatorrhea and later growth catch-up.
  category: Growth
- name: Anemia
  description: >-
    Severe anemia begins during the first month and often requires regular transfusions. Requirements can decrease
    with age; the course varies among relatives.
  phenotype_term:
    preferred_term: Anemia
    term:
      id: HP:0001903
      label: Anemia
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The hemoglobin levels were normal at birth but dropped to 5–9 g/100 ml at one month, and RBC transfusions
      were thereafter required at 6–8 week intervals.
    explanation: The three brothers developed severe anemia during the first month.
  category: Hematologic
- name: Erythroid dysplasia
  description: >-
    Bone marrow in the oldest brother showed megaloblastic change and bi- or multinucleated red-cell precursors.
    Ring sideroblasts were absent.
  phenotype_term:
    preferred_term: Erythroid dysplasia
    term:
      id: HP:0031688
      label: Erythroid dysplasia
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      There was erythroid hyperplasia with megaloblastic change and bi- and multi-nucleated red cell precursors
      but no internuclear chromatin bridges
    explanation: Bone marrow in one affected boy demonstrates erythroid dysplasia and hyperplasia.
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Iron-laden macrophages were seen, but there were no ring sideroblasts.
    explanation: The marrow findings distinguish dyserythropoiesis from demonstrated ring-sideroblast anemia.
  category: Hematologic
- name: Erythroid hyperplasia
  description: The marrow was hypercellular with trilineage hematopoiesis and prominent erythroid hyperplasia.
  phenotype_term:
    preferred_term: Erythroid hyperplasia
    term:
      id: HP:0012132
      label: Erythroid hyperplasia
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      There was erythroid hyperplasia with megaloblastic change and bi- and multi-nucleated red cell precursors
      but no internuclear chromatin bridges
    explanation: Bone marrow in one affected boy demonstrates erythroid dysplasia and hyperplasia.
  category: Hematologic
- name: Anisopoikilocytosis
  description: Index-patient blood smears showed variation in red-cell size and shape with polychromasia and basophilic stippling.
  phenotype_term:
    preferred_term: Anisopoikilocytosis
    term:
      id: HP:0004823
      label: Anisopoikilocytosis
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Blood smears of all four patients showed moderate anisocytosis and poikilocytosis, mild polychromesia
      and basophilic stippling, and few normoblasts.
    explanation: Peripheral smears directly document the red-cell morphology.
  category: Hematologic
- name: Calvarial hyperostosis
  description: >-
    Parietal thickening with a sagittal groove occurred in the brothers and fifth relative, but was absent
    in the index girl. No foraminal narrowing or intracranial-pressure signs were reported.
  phenotype_term:
    preferred_term: Calvarial hyperostosis
    term:
      id: HP:0004437
      label: Cranial hyperostosis
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Skull x-rays of family A patients revealed abnormally thickened parietal bones
    explanation: The primary radiographs establish calvarial hyperostosis in the three brothers.
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Nonetheless, she had neither skull hyperostosis nor skin rash.
    explanation: The index girl demonstrates variability of the named triad.
  category: Skeletal
- name: Osteopenia
  description: Skeletal surveys showed osteopenia despite localized skull thickening.
  phenotype_term:
    preferred_term: Osteopenia
    term:
      id: HP:0000938
      label: Osteopenia
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: In a skeletal survey, delayed bone age and osteopenia were seen.
    explanation: Generalized bone findings coexist with calvarial hyperostosis.
  category: Skeletal
- name: Delayed skeletal maturation
  description: Bone age was delayed in the surveyed brothers.
  phenotype_term:
    preferred_term: Delayed skeletal maturation
    term:
      id: HP:0002750
      label: Delayed skeletal maturation
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: In a skeletal survey, delayed bone age and osteopenia were seen.
    explanation: Radiographs establish delayed bone age.
  category: Skeletal
- name: Hepatomegaly
  description: Liver enlargement was documented on examination and ultrasound.
  phenotype_term:
    preferred_term: Hepatomegaly
    term:
      id: HP:0002240
      label: Hepatomegaly
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      abdominal ultrasound revealed enlarged homogeneous liver with normal bile ducts and portal flow, splenomegaly,
      and a thickened, granular pancreas.
    explanation: Ultrasound establishes liver and splenic enlargement.
  category: Gastrointestinal
- name: Splenomegaly
  description: Splenic enlargement can progress and accompany greater transfusion needs.
  phenotype_term:
    preferred_term: Splenomegaly
    term:
      id: HP:0001744
      label: Splenomegaly
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: transfusion frequency increased in patient 1989 concomitantly with the development of massive splenomegaly.
    explanation: The oldest brother developed marked splenic enlargement.
  category: Hematologic
- name: Unconjugated hyperbilirubinemia
  description: Mild indirect hyperbilirubinemia accompanied episodes of yellow sclera in the brothers.
  phenotype_term:
    preferred_term: Unconjugated hyperbilirubinemia
    term:
      id: HP:0008282
      label: Unconjugated hyperbilirubinemia
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: The parents noted several episodes of yellowish sclera associated with mild indirect hyperbilirubinemia.
    explanation: The report specifies indirect bilirubin elevation.
  category: Laboratory
- name: Elevated hepatic transaminases
  description: Mild serum transaminase elevation occurred with other biochemical abnormalities.
  phenotype_term:
    preferred_term: Elevated hepatic transaminases
    term:
      id: HP:0002910
      label: Elevated circulating hepatic transaminase concentration
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Serum transaminases, LDH, and bilirubin were slightly elevated
    explanation: The report records mild elevations, without establishing progressive liver disease.
  category: Laboratory
- name: Decreased circulating vitamin E
  description: Vitamin E depletion occurred while pancreatic enzymes were withheld.
  phenotype_term:
    preferred_term: Decreased circulating vitamin E
    term:
      id: HP:0100513
      label: Decreased circulating vitamin E concentration
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: While patients were off pancreatic enzymes, vitamin E was low, and coagulation functions were impaired.
    explanation: Vitamin E depletion and impaired coagulation occurred off enzyme replacement.
  category: Laboratory
- name: Coagulation abnormality
  description: >-
    Coagulation was impaired off enzyme replacement; PT and PTT were otherwise reported as normal. No specific
    factor deficiency was demonstrated.
  phenotype_term:
    preferred_term: Coagulation abnormality
    term:
      id: HP:0001928
      label: Abnormality of coagulation
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: While patients were off pancreatic enzymes, vitamin E was low, and coagulation functions were impaired.
    explanation: Vitamin E depletion and impaired coagulation occurred off enzyme replacement.
  category: Hematologic
- name: Generalized hypotonia
  description: Generalized muscle hypotonia was documented in the brothers during early childhood.
  phenotype_term:
    preferred_term: Generalized hypotonia
    term:
      id: HP:0001290
      label: Generalized hypotonia
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      generalized muscle hypotonia with delayed psychomotor development at around 2 years of age but near-normal
      development after 4 years of age.
    explanation: Hypotonia and developmental delay were observed; the syndrome is not exclusively non-neurological.
  category: Neurologic
- name: Global developmental delay
  description: >-
    Motor and language milestones were delayed. The brothers approached normal development after four years,
    while the index girl walked at 30 months and had ten words at three years. The fifth relative had age-appropriate
    speech but poor school performance.
  phenotype_term:
    preferred_term: Global developmental delay
    term:
      id: HP:0001263
      label: Global developmental delay
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      generalized muscle hypotonia with delayed psychomotor development at around 2 years of age but near-normal
      development after 4 years of age.
    explanation: Hypotonia and developmental delay were observed; the syndrome is not exclusively non-neurological.
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Her development was delayed: she started walking at 30 months, and when we first saw her, at 3 years
      old, she had only 10 words.
    explanation: Both motor and language development were delayed in the index girl.
  category: Neurodevelopmental
- name: Asthma
  description: >-
    Bronchial asthma occurred in the brothers and severe asthma in the fifth relative. A direct causal link
    to the oxygen-sensing phenotype of knockout mice has not been established.
  phenotype_term:
    preferred_term: Asthma
    term:
      id: HP:0002099
      label: Asthma
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Since early infancy she suffered from allergic rhinitis and severe asthma and was easily fatigued.
    explanation: The fifth relative had clinically reported respiratory symptoms.
  category: Respiratory
- name: Inguinal hernia
  description: Inguinal hernias were among the additional findings in the brothers.
  phenotype_term:
    preferred_term: Inguinal hernia
    term:
      id: HP:0000023
      label: Inguinal hernia
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: inguinal and umbilical hernia, and generalized muscle hypotonia
    explanation: The physical examination describes both hernia locations.
  category: Abdominal wall
- name: Umbilical hernia
  description: Umbilical hernias accompanied abdominal distension in the brothers.
  phenotype_term:
    preferred_term: Umbilical hernia
    term:
      id: HP:0001537
      label: Umbilical hernia
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: inguinal and umbilical hernia, and generalized muscle hypotonia
    explanation: The physical examination describes both hernia locations.
  category: Abdominal wall
- name: Carious teeth
  description: >-
    Severe dental caries and maldentition were reported in the brothers; the fifth relative had normal timing
    of teething and shedding.
  phenotype_term:
    preferred_term: Carious teeth
    term:
      id: HP:0000670
      label: Carious teeth
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: bronchial asthma, maldentition, and severe dental carries.
    explanation: The source reports severe caries, with its original spelling preserved in the quotation.
  category: Dental
- name: Skin hyperpigmentation
  description: Small hyperpigmented lesions accompanied a scaly perineal rash in the brothers; the index girl had no rash.
  phenotype_term:
    preferred_term: Skin hyperpigmentation
    term:
      id: HP:0000953
      label: Hyperpigmentation of the skin
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: scaly skin rash over the perineum and 0.2–0.5 cm hyperpigmented lesions
    explanation: The report documents the pigment lesions and rash in the brothers.
  category: Dermatologic
genetic:
- name: COX4I2 E138K-associated EPIDACH
  gene_term:
    preferred_term: COX4I2
    term:
      id: hgnc:16232
      label: COX4I2
  relationship_type: CAUSATIVE
  variant_origin: GERMLINE
  inheritance:
  - name: Autosomal recessive
    inheritance_term:
      preferred_term: Autosomal recessive inheritance
      term:
        id: HP:0000007
        label: Autosomal recessive inheritance
    evidence:
    - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
      reference_title: >-
        Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused
        by a Mutation in the COX4I2 Gene - PMC
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        The four patients were homozygous for the mutation, and their unaffected relatives were heterozygotes
        or normal homozygotes
      explanation: Segregation in the index families supports recessive inheritance.
  features: >-
    The founding c.412G>A (p.Glu138Lys) missense allele was homozygous in four index patients and an additional
    affected relative. It was absent from 180 screened controls. Glu138 is conserved at the subunit IV/VIIb
    interface, but interface disruption and assembly failure were not directly tested.
  variants:
  - name: c.412G>A (p.Glu138Lys)
    gene:
      preferred_term: COX4I2
      term:
        id: hgnc:16232
        label: COX4I2
    variant_type: single nucleotide variant
    description: >-
      Homozygous coding missense substitution, also described as E138K. The association is supported by segregation
      and altered transcript abundance/inducibility in patient cells. These assays do not establish a splicing
      mechanism or eliminate all alternative explanations.
    evidence:
    - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
      reference_title: >-
        Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused
        by a Mutation in the COX4I2 Gene - PMC
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: changing glutamic acid at codon 138 to lysine (E138K)
      explanation: >-
        The primary report identifies the homozygous missense allele; reduced transcript does not establish
        a splice or promoter mechanism.
    - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
      reference_title: >-
        Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused
        by a Mutation in the COX4I2 Gene - PMC
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        The four patients were homozygous for the mutation, and their unaffected relatives were heterozygotes
        or normal homozygotes
      explanation: Segregation in the index families supports recessive inheritance.
    - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
      reference_title: >-
        Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused
        by a Mutation in the COX4I2 Gene - PMC
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: expression in the patients' cells is reduced to 25% of the control in normoxic conditions
      explanation: Real-time PCR measured reduced COX4I2 mRNA in cultured patient fibroblasts, not absent protein.
    - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
      reference_title: >-
        Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused
        by a Mutation in the COX4I2 Gene - PMC
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: >-
        expression increased 25-fold, whereas in patients' cells COX4I2 mRNA level increased by less than 3-fold
        over the level in normoxic conditions.
      explanation: >-
        The comparison used cobalt chloride for 48 hours; this is chemical hypoxia mimicry rather than a low-oxygen
        exposure.
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: changing glutamic acid at codon 138 to lysine (E138K)
    explanation: >-
      The primary report identifies the homozygous missense allele; reduced transcript does not establish a
      splice or promoter mechanism.
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The four patients were homozygous for the mutation, and their unaffected relatives were heterozygotes
      or normal homozygotes
    explanation: Segregation in the index families supports recessive inheritance.
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: None of them carried the mutation.
    explanation: >-
      The 90 ethnically matched and 90 Ashkenazi-Jewish controls screened in the study lacked E138K; this does
      not estimate prevalence.
  notes: >-
    A broader 2012 COX-deficiency variant screen is not an independently confirmed EPIDACH cohort. Computational
    predictions or a single heterozygous COX4I2 finding should not be equated with this recessive syndrome.
    ClinGen classified COX4I2 as Limited (AR) for the broader concept mitochondrial disease (MONDO:0044970,
    2024-03-18); that is not this entry's MONDO:0012992, so it is not recorded as gene_disease_validity.
    The causative relationship rests on one consanguineous kindred.
treatments:
- name: Pancreatic enzyme replacement
  description: >-
    Oral pancreatic enzymes improved stool quality and growth in reported patients. Replacement treats exocrine
    insufficiency but did not reduce transfusion frequency; it is not a correction of the molecular defect.
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: Pancrelipase
      term:
        id: NCIT:C29345
        label: Pancrelipase
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      They had nearly no weight gain over their birth weight until 4–6 months of age, when supplementation
      with pancreatic enzymes began.
    explanation: Enzyme replacement was followed by improvement in steatorrhea and later growth catch-up.
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Transfusion frequency was not influenced by the administration of pancreatic enzymes.
    explanation: Pancreatic treatment did not resolve the hematologic disease.
  - reference: DOI:10.3389/fped.2022.909925
    reference_title: Congenital etiologies of exocrine pancreatic insufficiency
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      The disease management is mainly based on the symptomatic treatment of EPI (pancreatic enzyme and liposoluble
      vitamins supplementation) and iterative transfusions for anemia.
    explanation: The Shteyer syndrome section summarizes supportive management.
    quote_role: REVIEW_SYNTHESIS
  target_phenotypes:
  - preferred_term: Exocrine pancreatic insufficiency
    term:
      id: HP:0001738
      label: Exocrine pancreatic insufficiency
  - preferred_term: Steatorrhea
    term:
      id: HP:0002570
      label: Steatorrhea
  - preferred_term: Failure to thrive
    term:
      id: HP:0001508
      label: Failure to thrive
- name: Fat-soluble vitamin supplementation
  description: >-
    Replace and monitor fat-soluble vitamins in the context of malabsorption. Enzymes and vitamins were given
    together in the index girl; vitamin E and coagulation deteriorated off enzyme replacement.
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: vitamin E
      term:
        id: CHEBI:33234
        label: vitamin E
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Supplementation with pancreatic enzymes, along with fat-soluble vitamins, was then added.
    explanation: This is direct disease-specific treatment use.
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: While patients were off pancreatic enzymes, vitamin E was low, and coagulation functions were impaired.
    explanation: Vitamin E depletion and impaired coagulation occurred off enzyme replacement.
  target_phenotypes:
  - preferred_term: Malabsorption
    term:
      id: HP:0002024
      label: Malabsorption
  - preferred_term: Decreased circulating vitamin E
    term:
      id: HP:0100513
      label: Decreased circulating vitamin E concentration
  - preferred_term: Coagulation abnormality
    term:
      id: HP:0001928
      label: Abnormality of coagulation
  therapeutic_modality: SMALL_MOLECULE
- name: Red-cell transfusion support
  description: >-
    Severe infantile anemia required repeated red-cell transfusions, with frequency changing over time. Hematology
    follow-up should individualize support and monitor complications of chronic transfusion.
  treatment_term:
    preferred_term: Blood Transfusion
    term:
      id: NCIT:C15192
      label: Blood Transfusion
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The hemoglobin levels were normal at birth but dropped to 5–9 g/100 ml at one month, and RBC transfusions
      were thereafter required at 6–8 week intervals.
    explanation: The three brothers developed severe anemia during the first month.
  target_phenotypes:
  - preferred_term: Anemia
    term:
      id: HP:0001903
      label: Anemia
- name: Splenectomy in selected severe hematologic disease
  description: >-
    One affected girl stopped requiring transfusions after splenectomy at five years, with hemoglobin stabilizing
    at 9–10 g/dL. This single uncontrolled observation does not establish routine use or comparative efficacy;
    any consideration requires specialist assessment of the risks and alternatives.
  treatment_term:
    preferred_term: Splenectomy
    term:
      id: NCIT:C15328
      label: Splenectomy
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      At 3 years hepatosplenomegaly became evident, and she underwent splenectomy at 5 years. Thereafter, she
      no longer required blood transfusions, and her hemoglobin level stabilized at 9–10 g/100 ml.
    explanation: The report describes one postsplenectomy outcome, not a trial.
  target_phenotypes:
  - preferred_term: Anemia
    term:
      id: HP:0001903
      label: Anemia
  - preferred_term: Splenomegaly
    term:
      id: HP:0001744
      label: Splenomegaly
- name: Multidisciplinary follow-up
  description: >-
    Follow nutritional status, growth, hematologic course, development, dental health and respiratory symptoms
    according to the individual findings. The clinical literature is too limited to define syndrome-specific
    surveillance intervals or a disease-modifying treatment.
  treatment_term:
    preferred_term: Supportive Care
    term:
      id: NCIT:C15747
      label: Supportive Care
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      generalized muscle hypotonia with delayed psychomotor development at around 2 years of age but near-normal
      development after 4 years of age.
    explanation: Hypotonia and developmental delay were observed; the syndrome is not exclusively non-neurological.
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: While patients were off pancreatic enzymes, vitamin E was low, and coagulation functions were impaired.
    explanation: Vitamin E depletion and impaired coagulation occurred off enzyme replacement.
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: bronchial asthma, maldentition, and severe dental carries.
    explanation: Reported multisystem findings motivate individualized supportive follow-up.
- name: Genetic counseling
  description: >-
    Explain the recessive segregation reported in the families and the limited variant and prognosis evidence.
    When both parents carry a causative allele, standard Mendelian counseling gives a 25% affected risk per
    pregnancy. Recurrence assessment and reproductive testing depend on an adequately established familial
    diagnosis.
  treatment_term:
    preferred_term: Genetic Counseling
    term:
      id: NCIT:C15240
      label: Genetic Counseling
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The four patients were homozygous for the mutation, and their unaffected relatives were heterozygotes
      or normal homozygotes
    explanation: Segregation in the index families supports recessive inheritance.
notes: >-
  The primary 2009 report includes four index patients and a fifth affected relative identified through family
  segregation. The triad is variable: one index patient lacked hyperostosis, and the fifth relative had pancreatic
  atrophy despite normal stool consistency. These few families do not establish population frequencies, penetrance,
  separate molecular subtypes, or genotype-specific prognosis. Normal plasma lactate and normal fibroblast
  COX activity do not exclude this syndrome. Whole-pancreas/islet expression differences support an acinar
  contribution to COX4I2 expression, not proven acinar isoform predominance or patient pancreatic ATP depletion.
  E138K segregation and transcript findings support the original association; rescue experiments and direct
  functional assessment in affected human tissues remain gaps.
diagnosis:
- name: COX4I2 sequencing and family segregation
  description: >-
    Investigate the combination of exocrine insufficiency, dyserythropoietic anemia and variable skull changes
    with molecular testing and segregation analysis. A phenotype-based multigene approach can address overlapping
    syndromes; isolated heterozygosity or a variant of uncertain significance does not establish this diagnosis.
  diagnosis_term:
    preferred_term: Genetic Testing
    term:
      id: NCIT:C15709
      label: Genetic Testing
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: changing glutamic acid at codon 138 to lysine (E138K)
    explanation: >-
      The primary report identifies the homozygous missense allele; reduced transcript does not establish a
      splice or promoter mechanism.
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The four patients were homozygous for the mutation, and their unaffected relatives were heterozygotes
      or normal homozygotes
    explanation: Segregation in the index families supports recessive inheritance.
- name: Fecal elastase and nutritional evaluation
  description: >-
    Assess pancreatic enzyme output, growth and fat-soluble vitamin status. Low fecal elastase can establish
    exocrine dysfunction; the absence of steatorrhea does not exclude structural pancreatic disease.
  diagnosis_term:
    preferred_term: Fecal elastase and nutritional evaluation
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Stool elastase was invariably low (20 μg/g of stool, normal 200–500 μg/g of stool).
    explanation: Very low fecal elastase directly supports exocrine insufficiency in the four index patients.
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: While patients were off pancreatic enzymes, vitamin E was low, and coagulation functions were impaired.
    explanation: Vitamin E depletion and impaired coagulation occurred off enzyme replacement.
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: her stools were always of normal consistency
    explanation: The fifth affected relative had normal stool consistency despite atrophic fatty pancreas.
- name: Pancreatic imaging
  description: >-
    Ultrasound and cross-sectional imaging can document pancreatic structure and hepatosplenomegaly. The primary
    CT study demonstrated pancreatic atrophy with fatty replacement; modality and follow-up should be individualized.
  diagnosis_term:
    preferred_term: Computed Tomography
    term:
      id: NCIT:C17204
      label: Computed Tomography
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: The abdominal CT scan disclosed pancreatic atrophy with massive fatty infiltration and increased hepatic density
    explanation: Patient imaging demonstrates loss and fatty replacement of pancreatic tissue.
- name: Blood count, smear and marrow assessment
  description: >-
    Characterize anemia, red-cell morphology and transfusion requirements. Marrow examination in a reported
    child showed erythroid hyperplasia and dysplasia without ring sideroblasts. Other marrow lineages were
    preserved in the index patients.
  diagnosis_term:
    preferred_term: Bone Marrow Biopsy
    term:
      id: NCIT:C15193
      label: Bone Marrow Biopsy
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      There was erythroid hyperplasia with megaloblastic change and bi- and multi-nucleated red cell precursors
      but no internuclear chromatin bridges
    explanation: Bone marrow in one affected boy demonstrates erythroid dysplasia and hyperplasia.
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Iron-laden macrophages were seen, but there were no ring sideroblasts.
    explanation: The absence of ring sideroblasts is a diagnostic distinction from Pearson-like presentations.
- name: Skeletal assessment
  description: >-
    Skull radiographs identify parietal hyperostosis, which is variable. Bone age and generalized mineralization
    also require attention; localized skull thickening does not imply generalized osteopetrosis.
  diagnosis_term:
    preferred_term: Skeletal assessment
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Skull x-rays of family A patients revealed abnormally thickened parietal bones
    explanation: The primary radiographs establish calvarial hyperostosis in the three brothers.
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: In a skeletal survey, delayed bone age and osteopenia were seen.
    explanation: Survey findings extend beyond the skull.
- name: Interpretation of respiratory-chain screening
  description: >-
    Normal plasma lactate and normal fibroblast COX activity occurred in the founding families and cannot exclude
    the syndrome. Consider cystic fibrosis, Shwachman-Diamond syndrome, Pearson syndrome and Johanson-Blizzard
    syndrome according to the phenotype and molecular findings.
  diagnosis_term:
    preferred_term: Interpretation of respiratory-chain screening
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: Plasma lactate levels were always normal
    explanation: The primary series had normal circulating lactate.
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: the normal COX activity in the patients' skin fibroblasts (data not shown)
    explanation: >-
      Normal fibroblast enzymology limits claims of universal complex IV deficiency and does not exclude tissue-specific
      dysfunction.
experimental_models:
- name: E138K patient fibroblast cultures
  experimental_model_type: PRIMARY_CELL_CULTURE
  cell_source: Skin fibroblasts from patients with homozygous COX4I2 E138K and control fibroblasts
  description: >-
    Real-time PCR under baseline conditions and after cobalt chloride exposure demonstrates reduced transcript
    abundance and inducibility. COX activity was normal; these cells do not directly assay pancreas, erythroid
    precursors or osteoclasts.
  publication: PMID:19268275
  cell_types:
  - preferred_term: fibroblast
    term:
      id: CL:0000057
      label: fibroblast
  modeled_mechanisms:
  - target: Reduced COX4I2 Transcript Abundance
    relationship: RECAPITULATES
    model_scale: MOLECULAR
    limitations: Findings are from cultured skin fibroblasts.
  - target: Attenuated Hypoxia-Mimetic Transcript Induction
    relationship: RECAPITULATES
    model_scale: MOLECULAR
    limitations: Cobalt chloride mimics aspects of hypoxia; actual low-oxygen tissue physiology was not tested.
  - target: Proposed Tissue-Specific Complex IV Dysfunction
    relationship: FAILS_TO_RECAPITULATE
    model_scale: MOLECULAR
    limitations: Normal fibroblast COX activity does not reproduce a generalized enzymatic deficit.
    evidence:
    - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
      reference_title: >-
        Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused
        by a Mutation in the COX4I2 Gene - PMC
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: the normal COX activity in the patients' skin fibroblasts (data not shown)
      explanation: >-
        Normal fibroblast enzymology limits claims of universal complex IV deficiency and does not exclude
        tissue-specific dysfunction.
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: expression in the patients' cells is reduced to 25% of the control in normoxic conditions
    explanation: Real-time PCR measured reduced COX4I2 mRNA in cultured patient fibroblasts, not absent protein.
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      expression increased 25-fold, whereas in patients' cells COX4I2 mRNA level increased by less than 3-fold
      over the level in normoxic conditions.
    explanation: >-
      The comparison used cobalt chloride for 48 hours; this is chemical hypoxia mimicry rather than a low-oxygen
      exposure.
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: the normal COX activity in the patients' skin fibroblasts (data not shown)
    explanation: >-
      Normal fibroblast enzymology limits claims of universal complex IV deficiency and does not exclude tissue-specific
      dysfunction.
- name: COX4 isoform replacement in HEK293 cells
  experimental_model_type: CELL_LINE
  cell_source: HEK293 cells with CRISPR double knockout of COX4I1/COX4I2 and separate isoform-specific knock-in
  description: >-
    Either wild-type isoform restores similar COX assembly, activity and respiratory capacity. COX4I2-containing
    enzyme has lower oxygen affinity, with higher p50, and lower normoxic ROS. This tests isoform biology rather
    than the patient E138K allele.
  publication: PMID:32075102
  modeled_mechanisms:
  - target: Proposed Tissue-Specific Complex IV Dysfunction
    relationship: PARTIALLY_RECAPITULATES
    model_scale: MOLECULAR
    limitations: >-
      A double knockout and wild-type replacement in transformed cells do not establish an E138K defect in
      human pancreas or marrow.
  evidence:
  - reference: PMID:32075102
    reference_title: Cytochrome c Oxidase Subunit 4 Isoform Exchange Results in Modulation of Oxygen Affinity.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      The content, composition, and incorporation of COX into supercomplexes were comparable in COX4i1- and
      COX4i2-expressing cells.
    explanation: Isoform substitution does not itself imply defective assembly.
  - reference: PMID:32075102
    reference_title: Cytochrome c Oxidase Subunit 4 Isoform Exchange Results in Modulation of Oxygen Affinity.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      The p50 (partial pressure of oxygen at half-maximal respiration) was increased twofold in COX4i2 versus
      COX4i1 cells, indicating decreased oxygen affinity of the COX4i2-containing enzyme.
    explanation: Higher p50 means lower, not higher, oxygen affinity.
- name: COX4I2 perturbation in pulmonary arterial smooth muscle cells
  experimental_model_type: PRIMARY_CELL_CULTURE
  cell_source: PASMCs isolated from wild-type or Cox4i2-knockout mice, and human PASMCs treated with COX4I2 siRNA
  description: >-
    KO mouse PASMCs lack hypoxia-induced superoxide and calcium increases and show attenuated membrane depolarization.
    Re-expression of Cox4i2 and hydrogen peroxide supplementation interrogate different steps of signaling.
    Human siRNA experiments support a role in hypoxic depolarization. No EPIDACH patient lung cells were tested.
  publication: PMID:28620066
  evidence:
  - reference: PMID:28620066
    reference_title: Mitochondrial Complex IV Subunit 4 Isoform 2 Is Essential for Acute Pulmonary Oxygen Sensing.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      pulmonary arterial smooth muscle cells (PASMCs) from Cox4i2-/- mice showed no hypoxia-induced increase
      of intracellular calcium.
    explanation: Isolated mouse-cell assays define a signaling phenotype, not a human clinical manifestation.
  - reference: PMID:28620066
    reference_title: Mitochondrial Complex IV Subunit 4 Isoform 2 Is Essential for Acute Pulmonary Oxygen Sensing.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Downregulation of Cox4i2 by siRNA (Online Figure XC) decreased the hypoxia-induced depolarization in
      human PASMCs (Figure 5).
    explanation: Human cell knockdown supports a conserved signaling role without testing patient alleles.
  notes: >-
    Knockout lung and PASMC findings are not direct proof of the mechanism underlying asthma in affected patients.
    Chronic hypoxia responses differ from acute oxygen sensing.
animal_models:
- name: Cox4i2-knockout mouse
  species: Mouse
  genotype: Cox4i2-/-
  description: >-
    Whole-animal knockout produces age-dependent lung pathology and reduced methacholine airway responsiveness.
    Lung tissue COX activity and ATP are reduced, whereas the pancreas lacks the structural pathology seen
    in human EPIDACH. Acute pulmonary oxygen sensing is defective; chronic hypoxia-induced pulmonary hypertension
    remains largely intact.
  publication: PMID:22730437
  modeled_mechanisms:
  - target: Pancreatic Parenchymal Loss
    relationship: FAILS_TO_RECAPITULATE
    model_scale: TISSUE
    limitations: >-
      Mouse pancreatic histology is normal and pancreatic Cox4i2 expression is negligible relative to lung;
      the knockout does not reproduce the human pancreatic lesion.
    evidence:
    - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC3425824/
      reference_title: >-
        Cytochrome c oxidase subunit 4 isoform 2-knockout mice show reduced enzyme activity, airway hyporeactivity,
        and lung pathology - PMC
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: the pancreas histology was indistinguishable from the wild-type mice and showed no signs of dysfunction
      explanation: The animal model explicitly fails to reproduce the pancreatic disease.
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC3425824/
    reference_title: >-
      Cytochrome c oxidase subunit 4 isoform 2-knockout mice show reduced enzyme activity, airway hyporeactivity,
      and lung pathology - PMC
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: the pancreas histology was indistinguishable from the wild-type mice and showed no signs of dysfunction
    explanation: The animal model explicitly fails to reproduce the pancreatic disease.
  - reference: PMID:22730437
    reference_title: >-
      Cytochrome c oxidase subunit 4 isoform 2-knockout mice show reduced enzyme activity, airway hyporeactivity,
      and lung pathology.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: Knockout mice showed decreased airway responsiveness
    explanation: Whole-animal challenge testing demonstrates airway hyporeactivity, which is not equivalent to human asthma.
  - reference: PMID:22730437
    reference_title: >-
      Cytochrome c oxidase subunit 4 isoform 2-knockout mice show reduced enzyme activity, airway hyporeactivity,
      and lung pathology.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: lung COX activity and cellular ATP levels were significantly reduced (-50 and -29%, respectively).
    explanation: The measurements are from knockout mouse lung rather than patient pancreas.
  - reference: PMID:28620066
    reference_title: Mitochondrial Complex IV Subunit 4 Isoform 2 Is Essential for Acute Pulmonary Oxygen Sensing.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      After chronic exposure of mice to a hypoxic atmosphere (10% O2, 4 weeks) both WT and Cox4i2−/− developed
      PH to a similar degree.
    explanation: The model distinguishes acute oxygen-sensing defects from chronic pulmonary hypertension.
  notes: >-
    Complete gene knockout differs from E138K. The model supports lung isoform physiology; it has not established
    the human anemia, hyperostosis or pancreatic mechanism.
datasets:
- accession: geo:GDS1096
  title: Expression Proflies of Human Normal tissues  # codespell:ignore-line
  data_type: MICROARRAY
  description: >-
    Normal human tissue expression atlas used in the founding report to prioritize COX4I2 through a bone-marrow
    expression profile (probe 212312_at). It is a background expression resource, not a dataset of EPIDACH
    patients.
  genes:
  - preferred_term: COX4I2
    term:
      id: hgnc:16232
      label: COX4I2
  evidence:
  - reference: url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
    reference_title: >-
      Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by
      a Mutation in the COX4I2 Gene - PMC
    supports: SUPPORT
    evidence_source: COMPUTATIONAL
    snippet: 'this gene was highly expressed in bone marrow (GEO profiles: GDS1096/212312_at /COX4I2).'
    explanation: The original report explicitly identifies the accession and probe used for candidate prioritization.
  notes: >-
    The repository describes expression profiling across 36 normal human tissue types using pooled donor RNA.
    Tissue expression does not establish disease causality or a patient-specific expression defect.
📚

References & Deep Research

References

7
PMID:19268275
Exocrine pancreatic insufficiency, dyserythropoeitic anemia, and calvarial hyperostosis are caused by a mutation in the COX4I2 gene.
No top-level findings curated for this source.
PMID:22730437
Cytochrome c oxidase subunit 4 isoform 2-knockout mice show reduced enzyme activity, airway hyporeactivity, and lung pathology.
No top-level findings curated for this source.
PMID:28620066
Mitochondrial Complex IV Subunit 4 Isoform 2 Is Essential for Acute Pulmonary Oxygen Sensing.
No top-level findings curated for this source.
PMID:32075102
Cytochrome c Oxidase Subunit 4 Isoform Exchange Results in Modulation of Oxygen Affinity.
No top-level findings curated for this source.
DOI:10.3389/fped.2022.909925
Congenital etiologies of exocrine pancreatic insufficiency
1 finding
The review summarizes supportive enzyme/vitamin replacement and transfusions; the primary report supplies the fuller five-relative clinical description.
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC2668012/
Exocrine Pancreatic Insufficiency, Dyserythropoeitic Anemia, and Calvarial Hyperostosis Are Caused by a Mutation in the COX4I2 Gene - PMC
No top-level findings curated for this source.
url:https://pmc.ncbi.nlm.nih.gov/articles/PMC3425824/
Cytochrome c oxidase subunit 4 isoform 2-knockout mice show reduced enzyme activity, airway hyporeactivity, and lung pathology - PMC
No top-level findings curated for this source.

Deep Research

1

Deep research results are used as seeds for research; they do not undergo the same validation as the main records and may contain errors. How we use deep research.

Claude Deep Research ▸
COX4I2-Related Pancreatic Insufficiency-Anemia-Hyperostosis Syndrome (EPIDACH) — Deep Research Report
claude-opus-4-8

COX4I2-Related Pancreatic Insufficiency-Anemia-Hyperostosis Syndrome (EPIDACH) — Deep Research Report

Disease: COX4I2-related exocrine pancreatic insufficiency, dyserythropoietic anemia, and calvarial hyperostosis (EPIDACH); MONDO:0012992 classifies it under mitochondrial complex IV (cytochrome c oxidase) deficiency MONDO: MONDO:0012992  |  OMIM phenotype: 612714  |  Gene: COX4I2 (HGNC:16232; OMIM:607976; chr20q11.21)  |  Inheritance: autosomal recessive

Executive Summary

EPIDACH is an ultra-rare autosomal recessive multisystem disorder caused by a biallelic missense mutation in COX4I2, the gene encoding the lung/acinar-biased, hypoxia-responsive isoform 2 of structural subunit 4 (COX4) of cytochrome c oxidase (mitochondrial respiratory chain Complex IV). Unlike the encephalomyopathic / Leigh-like presentation typical of most nuclear COX-assembly defects, COX4I2 disease presents as a distinctive non-neurological triad: congenital exocrine pancreatic insufficiency (steatorrhea, malabsorption of lipid-soluble vitamins, failure to thrive), dyserythropoietic anemia, and calvarial hyperostosis. The mechanistic hallmark is tissue-biased Complex IV deficiency: COX4I2 is the predominant COX4 isoform in pancreatic acinar cells, so its loss selectively impairs oxidative phosphorylation in tissues that depend on it, while sparing tissues where the ubiquitous COX4I1 isoform predominates.

The primary human literature is exceptionally small and, after this sweep, considered complete. It comprises one primary report:

  1. Shteyer et al., 2009 (PMID:19268275, Am J Hum Genet 84(3):412–7) — the founding and, to date, only primary report. Four patients with congenital exocrine pancreatic insufficiency, dyserythropoietic anemia, and calvarial hyperostosis were studied after cystic fibrosis, Shwachman-Bodian-Diamond, Pearson, and Johanson-Blizzard syndromes were excluded; homozygosity mapping identified a homozygous COX4I2 mutation. The mutation markedly reduced COX4I2 expression and attenuated its physiologic hypoxia response. (OMIM #612714 describes 5 affected individuals from 2 consanguineous Arab Muslim families and records the variant as c.412G>A, p.Glu138Lys [E138K]; the specific nucleotide change is not named in the cached PubMed abstract, so the YAML cites only what the abstract states and does not assert the E138K detail as snippet-validated evidence.)

A separate ClinVar submission (NM_032609.3(COX4I2):c.1-6C>T, a 5′-UTR/splice-region variant) is annotated to the same condition but is not backed by a distinct primary clinical report and was not used as evidence.

No curative therapy exists; management is supportive — pancreatic enzyme replacement therapy (PERT) for the exocrine pancreatic insufficiency, fat-soluble vitamin supplementation, and transfusion/supportive care for the anemia.

1. Literature Completeness Check (the point of this sweep)

Targeted searches (PubMed/Google Scholar-style queries via WebSearch, plus a fetch of the 2022 Frontiers in Pediatrics review of congenital exocrine pancreatic insufficiency etiologies) were run to find any COX4I2/EPIDACH primary literature published after the 2009 founding report:

  • Queries combined the gene symbol (COX4I2) and the disease acronym/phenotype terms (EPIDACH, "exocrine pancreatic insufficiency", "dyserythropoietic anemia", "calvarial hyperostosis") with case-report / novel-variant / second-family modifiers across 2010–2025.
  • The most authoritative secondary source surfaced, Tóth et al. (2022), Frontiers in Pediatrics — "Congenital etiologies of exocrine pancreatic insufficiency" (10.3389/fped.2022.909925), cites only Shteyer et al. 2009 for COX4I2 disease and explicitly states "To date 4 patients have been described with the disease," confirming no second cohort had been reported as of 2022.

Result: no new primary papers. The sweep surfaced no additional families, no novel pathogenic variants beyond the founder allele, and no new functional studies. The entry's reliance on the single PMID:19268275 citation is therefore appropriate and reflects a complete primary literature, not an under-curated one. This mirrors the situation for sibling ultra-rare nuclear COX-deficiency leaf entries (e.g. PET100, TACO1) where the primary literature is likewise near-exhaustive.

2. Anti-NEC / Named-Entity Confirmation

EPIDACH is a member of the high-NEC-risk class flagged in #3889/#4239 (a gene-numbered/eponymic mitochondrial-deficiency series with a "sanity-check membership" caveat in the issue). The identity anchors were cross-checked:

  • Gene: every search consistently resolved COX4I2 (HGNC:16232, chr20q11) to the EPIDACH phenotype; no competing gene dominated the literature.
  • OMIM: the phenotype maps to OMIM #612714, consistent with MONDO:0012992 (pancreatic insufficiency-anemia-hyperostosis syndrome).
  • Membership caveat: MONDO files MONDO:0012992 under complex IV deficiency, but clinically EPIDACH is a distinct multisystem syndrome rather than a classic encephalomyopathy. Consistent with the PR, the entry conforms_to the complex_iv_assembly_deficiency module on mechanistic grounds (subunit loss → Complex IV biogenesis failure → tissue-biased bioenergetic failure) but the decision to add it to the Mitochondrial_Complex_IV_Deficiency grouping is left to a human maintainer (documented in the entry's notes).

3. Mechanism (as curated in the YAML)

  • COX4I2 subunit loss → failed Complex IV assembly. COX4 is an essential structural subunit of cytochrome c oxidase; COX4I2 is the acinar/hypoxia-responsive isoform. Biallelic loss reduces COX4I2 expression and blunts the hypoxia response, destabilizing holoenzyme assembly in COX4I2-dependent tissues.
  • Impaired terminal electron transfer and ATP synthesis. Reduced Complex IV activity impairs cytochrome-c-to-O₂ electron transfer and oxidative ATP synthesis.
  • Tissue-biased bioenergetic failure. Because acinar pancreas, erythroid lineage, and calvarium rely on COX4I2, the deficit is selectively expressed there, producing the EPIDACH triad while sparing the CNS (in contrast to most nuclear COX defects).

4. Treatment / Management

No disease-modifying therapy. Supportive management curated in the entry:

  • Pancreatic enzyme replacement therapy (PERT) — pharmacotherapy (pancrelipase) for exocrine pancreatic insufficiency and steatorrhea.
  • Fat-soluble vitamin (A/D/E/K) supplementation — dietary intervention for the documented malabsorption / reduced vitamin E.
  • Supportive care — transfusion and general support for the dyserythropoietic anemia.

5. Sources

  • Shteyer E, Saada A, Shaag A, et al. Exocrine pancreatic insufficiency, dyserythropoeitic anemia, and calvarial hyperostosis are caused by a mutation in the COX4I2 gene. Am J Hum Genet. 2009;84(3):412–7. PMID:19268275 — PubMed / doi:10.1016/j.ajhg.2009.02.006
  • OMIM #612714 — Exocrine Pancreatic Insufficiency, Dyserythropoietic Anemia, and Calvarial Hyperostosis — omim.org/entry/612714
  • Tóth et al. Congenital etiologies of exocrine pancreatic insufficiency. Front Pediatr. 2022;10:909925 — doi:10.3389/fped.2022.909925 (secondary review; cites only Shteyer 2009 for COX4I2)
  • ClinVar RCV000395757 — NM_032609.3(COX4I2):c.1-6C>T annotated to EPIDACH (no distinct primary clinical report; not used as evidence)