CAMLG-CDG (Congenital Disorder of Glycosylation, Type IIz) — Comprehensive Research Report

Summary

CAMLG-CDG is an ultra-rare, autosomal recessive congenital disorder of glycosylation (CDG) caused by biallelic loss-of-function variants in CAMLG (calcium-modulating ligand, encoding the CAML protein). It was first reported in a single 14-year-old male patient in 2022 by Wilson, Durin, Unal, and colleagues (Human Molecular Genetics) and is designated CDG2Z in OMIM (#620201; gene: CAMLG, OMIM 601118). CAMLG-CDG is the third* described human disorder of the TRC ("transmembrane domain recognition complex," also called the GET pathway) — following GET4-CDG (OMIM #618751, CATP4/UBL4A-family disorder) and GET3/ASNA1-related disease — establishing "TRC pathway disorders" as an emerging disease category distinct from the classical CDG mechanisms (glycan assembly/transfer enzymes, nucleotide-sugar transporters, or COG/vesicular-tethering defects) (Wilson et al. 2022, PMID:35262690).

Primary source for nearly all clinical/molecular/mechanistic content below: Wilson MP, Durin Z, Unal Ö, et al. "CAMLG-CDG: a novel congenital disorder of glycosylation linked to defective membrane trafficking." Hum Mol Genet. 2022;31(15):2571-2581. doi:10.1093/hmg/ddac055. PMID:35262690; PMCID:PMC9396942. This is the sole primary literature report to date; no independent second family has yet been published (searched September 2026).

1. Disease Information

What it is. CAMLG-CDG is a Type II CDG (glycan-processing/trafficking defect rather than assembly defect) presenting with a predominantly severe neurological phenotype — global developmental delay, hypotonia, spasticity, epilepsy, and structural brain abnormalities — arising from combined defects in N-linked and mucin-type O-linked glycan sialylation, secondary to disrupted membrane insertion of tail-anchored (TA) SNARE proteins in the Golgi.

Key identifiers: - MONDO: MONDO:0859357 (per the dismech curation stub for this disease, issue #12798 — a lead, not independently re-verified against the MONDO release in this session) - OMIM phenotype: #620201 — Congenital Disorder of Glycosylation, Type IIz (CDG2Z) - OMIM gene: 601118 — CALCIUM-MODULATING LIGAND; CAMLG - Gene identifiers: HGNC:1471; NCBI Gene ID 819; approved name "calcium modulating ligand"; chromosome 5q31.1 (hg38 ~chr5:134,737,608–134,752,705) - Reference transcript used in the report: NM_001745.4 - Inheritance: Autosomal recessive - Synonyms/aliases for the gene: CAML (protein), calcium-modulating cyclophilin ligand - Orphanet/ICD-10/ICD-11: No dedicated Orphanet or ICD codes were identified in this search — consistent with the condition's extreme rarity and single-patient status; it would fall under the general CDG-II ICD-10 code (E77.8, other disorders of glycoprotein metabolism) if coded clinically. - Data provenance:* All disease-level information is derived from a single published index case (a structured case report / mechanistic study), i.e., individual-patient-level data aggregated into one peer-reviewed report — not a registry or large cohort.

2. Etiology

Disease causal factor: Purely genetic/monogenic. Biallelic (here, homozygous) loss-of-function variation in CAMLG abrogates CAML protein expression, disrupting the TRC/GET tail-anchored protein insertion pathway.

Genetic risk factors: - The reported variant, c.633+4A>G (chr5:134,741,527A>G, GRCh38.p13), is a canonical splice-donor-region variant in intron 2 causing exon 2 skipping. - Consanguinity is the dominant risk factor identified: the patient is "the second child of consanguineous Turkish parents (fourth degree cousins)," with an unaffected older sibling and no other family history of metabolic disease (Wilson et al. 2022). This is the classic epidemiologic signature of an autosomal recessive founder/private variant surfacing through consanguineous mating. - No population allele-frequency data for this specific variant were retrievable in this session (gnomAD query not performed); given a single reported homozygote in a consanguineous pedigree, the variant is presumptively very rare/private. - No modifier genes have been reported (single case; no genotype-phenotype correlation possible yet).

Environmental/other risk factors: None reported or plausible — this is a purely monogenic ER/Golgi membrane-insertion disorder.

Protective factors: None reported. The report speculates (see mechanism/model-organism section below) that residual leaky splicing producing a small amount of functional CAML is what allows human survival, given that complete Camlg knockout is embryonic lethal in mice — this is an inferred within-patient mechanism of attenuation, not a population-level protective genetic variant.

Gene-environment interactions: None described; not applicable to this single-gene ER trafficking disorder.

3. Phenotypes

All phenotype data below derive from the one published patient (male, born 2007 at term; most recent evaluation at age 14) (Wilson et al. 2022, PMID:35262690). Frequencies are necessarily "1/1" (n=1); no population frequency data exist.

Neuroimaging (brain MRI, age 7 years): "very thin corpus callosum, atrophic brain stem, severe cerebral and cerebellar atrophy and diffuse hypomyelination" — HPO candidates: HP:0033725/HP:0002079 (Hypoplasia of the corpus callosum / Thin corpus callosum — HP:0002079 or HP:0033725), HP:0002099 or HP:0001272 (Cerebellar atrophy), HP:0002451 (Limb ataxia — not stated), HP:0007266 (Diffuse cerebral atrophy), HP:0002194 (Delayed gross motor development), HP:0002087/HP:0002012 (brainstem atrophy — map to HP:0007366 Cerebellar vermis atrophy / HP:0002080 or a generic "Abnormality of brainstem morphology"), and HP:0007305 (Abnormality of the cerebral white matter) / HP:0012448 (Delayed myelination) for diffuse hypomyelination.

Severity/progression: The phenotype is characterized as a static, severe encephalopathy after an early regression — not clearly progressive after the seizure-onset period, though long-term natural history is unknown from a single case followed to age 14. Seizures became well-controlled (4 years seizure-free on levetiracetam at last report), which is a meaningful treatment-response data point.

Quality of life impact: Not formally measured (no EQ-5D/SF-36/PROMIS data); qualitatively, the patient has profound functional dependency (gastrostomy-fed, intermittent respiratory support, nonverbal, needs support to sit), consistent with a severe pediatric neurodevelopmental CDG phenotype.

Pediatric framing: This is a congenital/infantile-onset disorder by definition (symptom onset at 3 months); there is no adult-onset or adult-recognized phenotype reported, and the disorder should not be conflated with adult presentations of unrelated Golgi trafficking disorders.

4. Genetic/Molecular Information

Causal gene: CAMLG (HGNC:1471; NCBI Gene 819; OMIM *601118), chromosome 5q31.1.

The reported pathogenic variant (single family, homozygous): - Genomic: chr5:134,741,527A>G (GRCh38.p13) - Transcript (NM_001745.4): c.633+4A>G — an intron 2 splice-donor-region variant, 4 bp into the intron - Predicted protein consequence: p.(Glu58ValfsTer80) via aberrant splicing - Splicing mechanism (functionally confirmed in patient fibroblasts): the variant causes skipping of exon 2 (461 nucleotides, 154 codons) with fusion of exons 1 and 3, producing a frameshift and premature termination. - RT-qPCR: "expression of the canonical CAMLG transcript was negligible" in patient fibroblasts vs. controls. - cDNA PCR: the normal full-length 624 bp amplicon was absent in patient fibroblasts, replaced by a truncated ~163 bp amplicon, "confirming that the c.633+4A>G variant causes skipping of exon 2." - Protein level: immunoblotting showed significantly reduced CAML protein in patient fibroblasts (P<0.05) — i.e., not a complete null at the protein level, consistent with leaky/residual normal splicing (see Mechanism section).

Variant classification: Not explicitly stated as an ACMG/AMP tier in the retrieved abstract/full-text excerpts; functionally it behaves as a hypomorphic loss-of-function allele (severe reduction, not complete absence, of protein) — this functional hypomorphism is proposed by the authors as the reason the patient is viable despite Camlg being an embryonic-lethal gene in mouse knockouts.

Zygosity/origin: Homozygous germline variant, inherited from consanguineous heterozygous-carrier parents (autosomal recessive).

Population frequency: Not retrieved in this session (gnomAD lookup not performed for this specific intronic variant); given a single reported homozygote from a consanguineous union, expect it to be absent or present at very low allele count in gnomAD — this should be independently verified via gnomAD/ClinVar before curation, not assumed from this report.

Modifier genes: None identified (n=1 case; no comparative genetics possible).

Epigenetics / chromosomal abnormalities: Not applicable/not reported for this disorder — it is a single-nucleotide splice variant, not a structural or epigenetic lesion.

Gene product function (CAML protein): - CAML (calcium-modulating cyclophilin ligand) is an ER-resident, widely expressed multipass transmembrane protein. - TRC/GET pathway role (disease-relevant mechanism): Together with GET1/WRB, CAML forms the ER membrane receptor component of the TRC (transmembrane domain recognition complex) pathway, which inserts C-terminal tail-anchored (TA) proteins into the ER membrane. Per the primary paper: "the recognition complex (composed of BAG6, GET4 and UBL4A)…binds to TA proteins and then to GET3 (TRC40, ASNA1)…GET3 chaperones the TA protein to the ER membrane where GET1 (WRB) and CAML form a receptor which enables its integration within the lipid bilayer." - Independent, non-CDG-related function (background/older literature, distinct from the 2022 disease report): CAML was originally characterized as a calcium-signaling protein downstream of the T-cell receptor and upstream of calcineurin/NFAT, binding cyclophilin B (Bram & Crabtree, Nature 1994, not independently re-verified in this session — flagged as background knowledge, not a primary-source citation obtained here). Later functional work (PMID:26561552, J Immunol 2015) showed CAML is required for survival of TCR-activated peripheral T cells — tamoxifen-inducible CAML-knockout T cells expressed normal early activation markers (CD25, CD69) and produced IL-2 normally but proliferated less and died, implicating CAML in a late post-activation T-cell survival step rather than early signaling. A separate paper (PMID:16111633, not independently verified this session) reported CAML is required for thymocyte development, with CAML inactivation reducing double-positive/single-positive thymocyte numbers and altering positive/negative selection. - Note for dismech curation (§3a-type lump/split consideration): these T-cell/immune functions of CAML are a separate, non-disease-linked biological role of the same gene — the one reported patient's phenotype is neurological, not immunological (no immunodeficiency features described), so this T-cell biology should be treated as background gene function rather than imported as a clinical feature of CAMLG-CDG absent direct patient evidence.

5. Environmental Information

No environmental factors, lifestyle factors, or infectious triggers are described or plausible for this monogenic ER-trafficking disorder. Not applicable.

6. Mechanism / Pathophysiology

Ordered causal chain (as established in Wilson et al. 2022, PMID:35262690)

1. Homozygous c.633+4A>G splice variant in CAMLG → causes skipping of exon 2 (RT-PCR/cDNA-confirmed) → frameshift/premature termination (p.Glu58ValfsTer80) → near-loss of canonical CAMLG transcript and markedly reduced CAML protein (immunoblot-confirmed, P<0.05) in patient fibroblasts.
2. Reduced/absent functional CAML → loss of the CAML/GET1(WRB) ER-membrane receptor component of the TRC (GET) pathway → impaired insertion of a subset of tail-anchored (TA) proteins into ER/Golgi membranes, specifically Golgi SNARE machinery.
3. Specifically, short-form syntaxin-5 (STX5S) and, to a lesser extent, long-form (STX5L) are mislocalized from Golgi membrane to cytosol — crude subcellular fractionation showed significantly increased cytoplasmic STX5 in both forms (P<0.05 long form, P<0.001 short form), with the short form more affected (43% mislocalized in CAMLG-CDG vs. 9% for the long form); immunofluorescence confirmed reduced STX5 colocalization with the Golgi marker giantin (P<0.0001). This was reproduced by siRNA knockdown of CAMLG in HeLa cells (residual CAML ~2%), reproducing STX5S (P<0.001) and STX5L (P<0.01) mislocalization — establishing STX5 mislocalization as a consistent cellular biomarker of TRC pathway dysfunction across two independent cell systems.
4. Downstream v-SNARE BET1L (GS15) — which the authors note is "more associated with the short form than the long form of STX5, and is required for retrograde trafficking within the Golgi" — is drastically reduced at the protein level: 37% of control levels in CAMLG-CDG fibroblasts and 27% of control in GET4-CDG fibroblasts (P<0.01; comparator disorder, see below), and reduced to 30.3% of control in CAMLG-siRNA-knockdown HeLa cells (P<0.01). BET1L/YKT6 localization (membrane vs. cytoplasm fractionation) was normal — the defect is in overall steady-state protein level, not mislocalization, distinguishing this from the STX5 mechanism.
5. Loss of correctly assembled/positioned Golgi SNARE complexes (STX5-BET1L axis) → impaired Golgi trafficking machinery → disorganized Golgi — indirectly supported by ST6GAL1 (a sialyltransferase) showing normal total protein levels but "a more fragmented distribution" upon CAMLG knockdown, "indicating at least some disorganization of the Golgi."
6. Golgi disorganization / impaired SNARE-dependent trafficking of glycosylation enzymes → hyposialylation of both N-linked and mucin-type O-linked glycans, producing the combined Type II CDG biochemical signature:
7. Serum transferrin isoelectric focusing: "repeatedly showed a type 2 pattern."
8. Transferrin N-glycan MALDI-TOF: CDG-II pattern with reduced pentasialotransferrin and raised trisialotransferrin (undersialylated species).
9. ApoC-III (mucin-type O-glycosylation marker): "absence of asialo and disialo apoC-III, and only a small amount of monosialo apoC-III," indicating a defect of mucin-type O-glycosylation.
10. Lectin studies in patient fibroblasts: peanut agglutinin (PNA) fluorescence (binds desialylated core-1 O-glycan/Gal-GalNAc) was "barely detectable in control fibroblasts" but showed "a strong increase in signal…in affected fibroblasts" — direct evidence of O-glycan hyposialylation. In contrast, vicia villosa lectin (VVL) (binds the unmodified GalNAc/Tn antigen, marking O-glycan initiation) "showed no increased signal in affected fibroblasts" — demonstrating the defect is specifically in the terminal sialylation step, not in O-glycan chain initiation.
11. Combined N- and O-glycan hyposialylation → the multisystem CDG phenotype, dominated here by severe CNS involvement (hypomyelination, cerebral/cerebellar atrophy, thin corpus callosum), consistent with the general CDG pattern in which the developing brain is exquisitely sensitive to glycosylation defects (general CDG biology; this generalization is background knowledge, not a specific claim from the cited paper about mechanism of CNS vulnerability, and should be flagged as inferred/general in KB curation rather than disease-specific evidence).

Branch/negative control — TRC pathway selectivity is incomplete: Not all canonical TRC-dependent TA proteins are affected. The authors explicitly tested and found normal subcellular localization of Emerin, VAMP7, and VAPB — TA proteins canonically dependent on the TRC pathway — in both CAMLG-CDG and GET4-CDG fibroblasts, indicating the pathway defect in this disease selectively/preferentially disrupts Golgi SNARE proteins (STX5, BET1L) rather than causing indiscriminate failure of all TA protein insertion. This is an important qualifying/branching point in the causal chain: reduced CAML causes a selective TA-protein trafficking defect, not global ER insertion failure, which the authors propose explains why glycosylation (a Golgi-dependent process) is specifically hit.

COG complex (a separate Golgi-tethering machinery) is not involved: steady-state levels and subcellular localization of COG1, COG4, and COG8 were normal in both CAMLG-CDG and GET4-CDG fibroblasts — ruling out a COG-complex-mediated mechanism (distinguishing this from the COG-CDG subgroup, CDG-IIa/IIc/IIe/etc.) and supporting that the TRC/SNARE-insertion defect is a mechanistically distinct route to hyposialylated CDG-II glycosylation.

Comparative mechanism — GET4-CDG (the closest prior TRC disorder)

The paper studied a previously reported GET4-deficient patient's fibroblasts in parallel: - "In fibroblasts from the previously identified individual with pathogenic variants in GET4, CAML steady state levels were normal." Interestingly, GET4 levels were also decreased in the CAMLG-CDG patient (~71% reduction versus controls), suggesting some interdependence/cross-stabilization between TRC pathway components even though CAML and GET4 act at different pathway steps. - STX5 mislocalization was reproduced in GET4-deficient fibroblasts in parallel with CAMLG-CDG, and clinical features of the CAMLG patient were noted to be "similar to those in one of the two other described TRC pathway disorders (GET4 deficiency)" — supporting a shared clinical/mechanistic disease class ("TRC pathway disorders").

Mouse model context (interpretive, not a primary-model experiment in this paper)

The authors note that complete Camlg knockout is embryonic lethal in mice, and interpret patient survival as evidence that "the small amount of remaining CAML protein…[is] sufficient to provide enough insertion of TA proteins that the phenotype is attenuated" — i.e., the human splice variant is a hypomorph, not a true null, and this residual function is proposed as necessary for viability. This is a model-organism-informed inference about human genotype-phenotype correlation (HUMAN_MODEL_MISMATCH-flavored reasoning: the mouse null is embryonic lethal, but the human hypomorphic allele produces a viable, severely affected phenotype) rather than a direct functional experiment performed in this paper on a mouse model.

Suggested ontology terms for the mechanism

• GO Biological Process: GO:0071816 (tail-anchored membrane protein insertion into ER membrane); GO:0006890 (retrograde vesicle-mediated transport, Golgi to ER — for BET1L's role); GO:0006486 (protein glycosylation); GO:0006493 (protein O-linked glycosylation); GO:0006487 (protein N-linked glycosylation)
• GO Molecular Function: consider GO terms for SNARE binding/protein-membrane receptor activity of CAML/GET1
• GO Cellular Component: GO:0005794 (Golgi apparatus); GO:0000139 (Golgi membrane); GO:0005783 (endoplasmic reticulum)
• Cell types (CL): primary evidence is from patient dermal fibroblasts (CL:0000057, fibroblast) and HeLa cells (an epithelial-derived cell line, less directly CL-mappable as a disease-relevant cell type but used for the siRNA mechanistic confirmation) — no direct neuronal/CNS cell-type-specific experiment was performed; the CNS phenotype is inferred from general CDG biology, not from a CNS-specific cell model in this paper.

7. Anatomical Structures Affected

• Organ level (primary): Central nervous system — cerebrum, cerebellum, brainstem, corpus callosum (structural MRI abnormalities: cerebral/cerebellar atrophy, thin corpus callosum, brainstem atrophy, diffuse hypomyelination). UBERON: UBERON:0000955 (brain), UBERON:0002037 (cerebellum), UBERON:0002771 (falx cerebri/corpus callosum — use UBERON:0002336 corpus callosum), UBERON:0002298 (brainstem).
• Secondary/systemic involvement: Growth (failure to thrive — below 3rd centile weight/OFC), musculoskeletal (contractures, spasticity), respiratory system (requiring intermittent support), gastrointestinal (gastrostomy-dependent feeding).
• Not involved / explicitly normal: No organomegaly noted; eye movements normal (no overt ophthalmologic/oculomotor involvement reported, unlike some other CDGs).
• Tissue/cell level: Dermal fibroblasts (patient-derived, primary experimental system) — CL:0000057. Golgi apparatus and ER of these cells are the direct subcellular site of the trafficking defect.
• Subcellular level (GO Cellular Component): Golgi membrane (GO:0000139) and ER membrane (GO:0005789) are the two organelle membranes directly implicated — CAML/GET1 receptor acts at the ER membrane for TA protein insertion, while the functional consequence (STX5/BET1L dysfunction) manifests at the Golgi.
• Laterality: Not applicable/not described (a systemic biochemical-trafficking disorder, not a lateralized structural anomaly).

8. Temporal Development

• Onset: Infantile — developmental delay and seizure onset both noted at 3 months of age. This is congenital-to-early-infantile onset by the standard CDG onset categories.
• Onset pattern: Insidious/subacute — a normal-appearing early infancy followed by loss of milestones concurrent with seizure onset at 3 months ("developmental delay at three months of age...seizures started at that age and he lost his milestones").
• Progression: The published natural history covers birth to age 14 (single longitudinal case, not a cohort). The picture is one of an early regression followed by a static but severe encephalopathy — seizures came under control (seizure-free 4 years on levetiracetam by last report), while the motor/functional profile (spasticity, contractures, need for gastrostomy and respiratory support) appears to represent a fixed, severe deficit state rather than a described progressive/degenerative course after the initial regression, though this cannot be fully distinguished from slow progression given only two time points (age 7 MRI, age 14 exam) were reported.
• Disease stage/duration: Chronic, lifelong — no data on adult survival beyond age 14 (patient's age at last follow-up in the report).
• Remission patterns: Partial — seizures achieved sustained remission with levetiracetam (treatment-induced, not spontaneous); no remission of the underlying developmental/motor phenotype is described (nor biologically expected, given the fixed genetic and structural brain basis).
• Critical periods: Not explicitly studied, but the infantile onset with regression suggests the first months of life are a period of particular vulnerability, consistent with general CDG biology (rapid CNS myelination and glycosylation-dependent processes in infancy) — this is a general inference, not paper-specific data.

9. Inheritance and Population

• Epidemiology: n = 1 reported patient worldwide (as of the 2022 publication and as of this September 2026 search, no additional cases were located in the literature). No prevalence or incidence estimate exists or is calculable; this is an ultra-rare, essentially "cases-in-literature" epidemiology (CASES_IN_LITERATURE measure type, in dismech schema terms).
• Inheritance pattern: Autosomal recessive, confirmed by parental consanguinity and homozygosity of the proband.
• Penetrance: Cannot be assessed from a single case (parents, presumed obligate heterozygous carriers, were not reported to have any phenotype — consistent with typical AR carrier status, but this is not explicitly discussed in the retrieved text).
• Expressivity: Cannot be assessed (n=1; no comparator patients).
• Genetic anticipation: Not applicable (no repeat-expansion mechanism; not a multi-generational report).
• Germline mosaicism: Not discussed/not applicable (single conventional homozygous transmission from two heterozygous consanguineous parents).
• Founder effects: Not established — a single Turkish consanguineous family; whether this specific variant represents a Turkish founder allele or a private familial mutation cannot be determined from one report. This would need gnomAD/regional-cohort data to assess (not retrieved in this session).
• Consanguinity role: Central to this case — parents are fourth-degree cousins of Turkish origin; this is the mechanism by which a presumably rare recessive allele became homozygous.
• Carrier frequency: Unknown/not reported.
• Population demographics: Only known ethnicity is Turkish (single family); no broader geographic or ethnic distribution data exist. Sex: only a male patient has been reported (n=1, cannot establish a sex ratio). Age distribution: single pediatric/adolescent patient (followed birth–14 years).

10. Diagnostics

Biochemical/laboratory tests (primary diagnostic route, as used in this case): - Serum transferrin isoelectric focusing (IEF): showed a repeatable Type 2 pattern — the standard first-tier CDG screening test, here indicating a Golgi-processing (Type II) rather than ER-assembly (Type I) defect. - Transferrin N-glycan analysis by MALDI-TOF mass spectrometry: confirmed the CDG-II pattern with reduced pentasialotransferrin and increased trisialotransferrin — quantitative confirmation of undersialylation. - Serum Apolipoprotein C-III (apoC-III) isoform analysis: used as the O-glycosylation marker; showed absence of asialo-/disialo-apoC-III and only trace monosialo-apoC-III, diagnostic of a mucin-type O-glycosylation defect — important because this combined N+O defect pattern is itself a diagnostic clue pointing away from classical single-pathway CDGs toward a Golgi-trafficking-level defect. - Lectin fluorescence microscopy in cultured fibroblasts (PNA vs. VVL): a research-level cellular assay (not a routine clinical diagnostic test) used here to localize the defect specifically to the sialylation step of O-glycosylation rather than initiation.

Genetic testing: The diagnosis was reached via genome/exome-level sequencing identifying the homozygous CAMLG splice variant (specific sequencing modality — WES vs. WGS vs. panel — not specified in the retrieved excerpts); given the phenotype's severity and the era (patient evaluated to age 14, report published 2022), exome sequencing in a consanguineous family with a "CDG-II biochemical signature + neurological phenotype" gene panel/WES approach is the most likely diagnostic route. Functional/RNA-level confirmation (RT-qPCR, RT-PCR of cDNA showing exon 2 skipping, and immunoblot showing reduced CAML protein) was essential to establish pathogenicity of this intronic splice variant — illustrating that for CDG genes with unclear-significance intronic/splice variants, RNA and protein studies in patient fibroblasts are the diagnostic gold standard beyond DNA sequencing alone.

Imaging: Brain MRI (structural) — thin corpus callosum, brainstem atrophy, cerebral/cerebellar atrophy, diffuse hypomyelination — performed at age 7.

Electrophysiology: Seizure semiology described clinically; specific EEG findings were not detailed in the retrieved excerpts.

Differential diagnosis: Broadly, other Type II CDGs presenting with severe neurological phenotype and combined N-/O-glycosylation defects (e.g., COG-CDGs, other Golgi-trafficking CDGs) and, specifically within the emerging TRC-disorder class, GET4-CDG — clinically the closest comparator per the authors. Standard CDG diagnostic algorithms (transferrin IEF/MALDI-TOF as first-tier, followed by gene-specific or panel/exome sequencing) apply.

Screening: No population or newborn screening applicable (single case, no established screening program for CDGs of this type generally, let alone this ultra-rare subtype).

11. Outcome/Prognosis

• Survival: The patient was alive at last follow-up (age 14), demonstrating this genotype is compatible with survival to adolescence despite the corresponding mouse knockout being embryonic lethal — a key prognostic and mechanistic data point (interpreted by the authors as reflecting residual/hypomorphic CAML function from incomplete splice disruption).
• Life expectancy: Not established beyond the reported follow-up age; no long-term mortality data exist for this single-patient disorder.
• Morbidity/functional outcome: Severe and static-to-slowly evolving — profound motor impairment (sits only with support), nonverbal communication, gastrostomy-dependent nutrition, intermittent respiratory support — indicating a high burden of chronic disability typical of severe pediatric CDGs with CNS involvement.
• Complications: Feeding/nutritional compromise (requiring gastrostomy), respiratory insufficiency (requiring intermittent support), contractures/spasticity as secondary musculoskeletal complications of chronic hypertonia/immobility.
• Recovery potential: Seizures show good treatment response (sustained remission on levetiracetam); the structural brain abnormalities and motor/developmental impairments are not described as reversible.
• Prognostic factors: None can be statistically derived from n=1; qualitatively, early seizure onset and severe MRI abnormalities correlate with the severe overall phenotype in this patient, consistent with (but not independently proving) a general CDG pattern that early-onset epilepsy plus significant structural brain disease predicts poor functional outcome.

12. Treatment

No disease-specific or mechanism-targeted therapy exists for CAMLG-CDG; management reported is purely supportive/symptomatic:

• Antiepileptic pharmacotherapy: Levetiracetam — patient became and remained seizure-free for 4 years at last report. (NCIT treatment-action term: NCIT:C15986 Pharmacotherapy, with therapeutic_agent bound to the specific drug — CHEBI ID for levetiracetam would need independent lookup/verification, not retrieved in this session.)
• Nutritional support: Gastrostomy tube feeding for chronic feeding difficulty (NCIT candidate: a gastrostomy/enteral feeding procedure term — exact NCIT code not verified in this session).
• Respiratory support: Intermittent respiratory support (ventilatory/respiratory assistance — NCIT candidate term not verified in this session).
• No gene therapy, enzyme replacement, cell therapy, RNA-based therapy, or disease-modifying treatment has been reported or trialled for this disorder (consistent with its status as a single-case, very recently described condition; unlike PMM2-CDG, there is no dedicated clinical trial infrastructure).
• No clinical trials (ClinicalTrials.gov / WHO ICTRP) specific to CAMLG-CDG were identified.

Treatment strategy: Purely symptomatic/multidisciplinary supportive care (neurology for seizure management, nutrition/GI for gastrostomy feeding, pulmonology for respiratory support) — the standard approach for a severe, non-treatable Type II CDG with predominant CNS involvement.

13. Prevention

• Primary prevention: None specific to this disorder beyond general genetic counseling; given the demonstrated role of consanguinity in this case, standard genetic counseling regarding consanguineous unions and recessive disease risk is the only "prevention" lever identifiable from the available data.
• Secondary prevention/screening: No population or targeted carrier-screening program exists (ultra-rare, single-family-described variant); prenatal or preimplantation genetic testing would be theoretically possible for this specific family once the causal variant is known (standard for a molecularly characterized AR disorder), but this was not reported as having occurred or being offered in the paper.
• Genetic counseling: Applicable for the affected family (recurrence risk 25% for future pregnancies of the same parents; carrier risk for the unaffected sibling) — general AR genetics principles, not disease-specific data from the paper.
• Public health/prophylaxis: Not applicable to this ultra-rare monogenic disorder.

14. Other Species / Natural Disease

• Taxonomy: No naturally occurring CAMLG-deficient disease has been reported in any non-human species (companion animal, livestock, or wildlife) in the literature searched. Camlg orthologs exist across mammals (the original CAMLG gene-mapping paper noted synteny with mouse chromosome 13; NCBITaxon:10090 for Mus musculus ortholog Camlg, MGI-mapped — exact MGI ID not independently verified in this session).
• Comparative biology: CAML/the TRC-GET pathway is evolutionarily conserved from yeast (where the pathway was first characterized: Get1/Get2/Get3/Get4/Get5 in Saccharomyces cerevisiae) to humans, underlying the pathway's alternate name "GET pathway" (Guided Entry of Tail-anchored proteins). This conservation is the basis for the yeast nomenclature (GET1=WRB, GET3=ASNA1/TRC40, GET4) used interchangeably with the mammalian TRC pathway naming in the primary paper.
• Zoonotic potential: Not applicable (not an infectious disease).

15. Model Organisms

• Mouse (Mus musculus): The primary paper cites that complete germline Camlg knockout is embryonic lethal in mice (cited as prior literature within Wilson et al. 2022, exact original mouse-knockout citation not independently retrieved/verified in this session — flag as a claim requiring its own primary-source PMID before KB citation). This model demonstrates CAML is essential for viability at the whole-organism level in a way that overlaps only partially with the human hypomorphic-allele phenotype — a human-model mismatch worth flagging explicitly in curation (HUMAN_MODEL_MISMATCH): the mouse null is incompatible with life, while the human splice-hypomorph is compatible with survival to at least adolescence, which the authors attribute to residual protein rather than to any species-specific difference in CAML's essentiality.
• Conditional/inducible mouse models (immune-function studies, mechanistically related but not disease models per se): Tamoxifen-inducible CAML-knockout mice (tCAML−/−) were used in unrelated immunology work (PMID:26561552) to study T-cell survival post-TCR activation, and thymocyte-specific CAML inactivation was studied in PMID:16111633 for T-cell development — these are functional/mechanistic models of CAML biology in the immune system, not models of the CDG phenotype, and should not be conflated with CAMLG-CDG animal-model evidence in KB curation; they establish gene function generally but were not designed or used to recapitulate the glycosylation/neurological disease phenotype.
• Cellular models used directly for CAMLG-CDG mechanism (the actual disease models in the primary paper):
• Patient-derived primary dermal fibroblasts — the principal disease model, used for RT-PCR/RT-qPCR splicing confirmation, immunoblotting (CAML, GET4, STX5, BET1L, YKT6, COG1/4/8, ST6GAL1), subcellular fractionation, and immunofluorescence (STX5/giantin colocalization; PNA/VVL lectin staining).
• HeLa cells with siRNA-mediated CAMLG knockdown (residual CAML ~2%) — used as an independent, non-patient-derived cellular system to confirm STX5 mislocalization and BET1L reduction, establishing reproducibility of the mechanism outside the patient's own genetic background — this fidelity/reproducibility is a strength of the mechanistic evidence (RECAPITULATES-type relationship in dismech modeled_mechanisms terms).
• GET4-deficient patient fibroblasts (from a previously published, separate patient) — used as a comparator TRC-pathway-disorder cell line, not a model of CAMLG-CDG itself, but establishing shared downstream mechanism (STX5 mislocalization, BET1L reduction) across two distinct TRC pathway gene defects.
• No zebrafish, Drosophila, C. elegans, or yeast disease-modeling experiments were performed in this paper (the yeast GET pathway is referenced only as evolutionary/mechanistic background, not as an experimental model in this study).
• No organoid, iPSC-derived, or CNS-specific (neuronal) model system was used — this is a notable gap: despite the phenotype being predominantly neurological (hypomyelination, brain atrophy), all functional/mechanistic work was performed in fibroblasts and HeLa cells, not neural cell types. This is worth flagging as a limitation/gap for any HUMAN_MODEL_MISMATCH or knowledge-gap discussion in KB curation — the CNS-specific pathophysiology (why hypomyelination and cerebellar/cerebral atrophy specifically result from this Golgi-SNARE/sialylation defect) is inferred by analogy to general CDG neurobiology rather than directly demonstrated in a neural model in this paper.

Notes on Evidence Quality and Gaps for Curation

• Single-source, single-patient disease. Essentially all clinical and molecular content in this report traces to one peer-reviewed paper (PMID:35262690) describing one family/one patient. This should be reflected in dismech curation as CASES_IN_LITERATURE for prevalence, and every phenotype should carry a frequency understood as "1/1," not a population percentage.
• OMIM (#620201, *601118) and GeneCards/NCBI/HGNC identifiers were retrieved via web search/API (mygene.info, OMIM search snippets) rather than fully fetched primary pages (OMIM blocked direct fetch with 403 in this session) — the OMIM clinical synopsis full text was not independently verified; treat the OMIM-sourced phrasing above as a lead requiring direct confirmation against omim.org before citing OMIM as a reference: in KB YAML.
• MONDO:0859357 is carried over from the dismech repository's own open curation-stub issue (#12798) referencing this exact disease — this is a strong internal signal of correctness for this specific dismech instance, but was not independently re-derived from a live MONDO ontology query in this session and should still be confirmed via just fetch-reference / term-cache lookup per repository ontology-term-contract rules before binding.
• HGNC:1471 for CAMLG was cross-verified via the mygene.info API (an independent source from the initial GeneCards-derived search snippet, which had first reported a slightly different number) — treat HGNC:1471 as the better-supported value, but re-confirm via just validate-terms / the HGNC cache per the repository's "never write a CURIE from memory" rule.
• The mouse Camlg embryonic-lethality claim is cited within the primary paper but its ultimate original source (the specific mouse knockout study) was not independently traced/verified in this session — if used in KB curation as an animal_models entry, the original PMID for that mouse knockout paper should be located and cited directly rather than citing Wilson et al. 2022 as if it were the source of the mouse data.
• No independent second case report, natural-history study, registry entry, or treatment trial exists as of this search (September 2026) — this is consistent with the disease's very recent (2022) first description and extreme rarity.

Sources

• CAMLG-CDG: a novel congenital disorder of glycosylation linked to defective membrane trafficking — Human Molecular Genetics (Oxford Academic)
• CAMLG-CDG: a novel congenital disorder of glycosylation linked to defective membrane trafficking — PubMed (PMID:35262690)
• CAMLG-CDG: a novel congenital disorder of glycosylation linked to defective membrane trafficking — PMC (PMCID:PMC9396942)
• OMIM #620201 — Congenital Disorder of Glycosylation, Type IIz (CDG2Z)
• OMIM *601118 — Calcium-Modulating Ligand; CAMLG
• GeneCards — CAMLG Gene
• NIH Genetic Testing Registry — Congenital disorder of glycosylation, type IIz
• Congenital disorders of glycosylation (CDG): state of the art in 2022 — Orphanet Journal of Rare Diseases
• Calcium-Modulating Cyclophilin Ligand Is Essential for the Survival of Activated T Cells and for Adaptive Immunity — J Immunol (PMID:26561552)
• CAML is a p56Lck-interacting protein that is required for thymocyte development — PubMed (PMID:16111633)
• OMIM *612056 — Guided Entry of Tail-Anchored Proteins Factor 4; GET4
• OMIM *602915 — Guided Entry of Tail-Anchored Proteins Factor 1; GET1 (WRB)
• dismech GitHub issue #12798 — Curate congenital disorder of glycosylation, type IIz (MONDO:0859357)
• mygene.info gene record for CAMLG (NCBI Gene 819)

Reference Validation

Checked with linkml-reference-validator 0.3.0rc1.

All extracted references resolved successfully.

Term Validation

Checked with linkml-term-validator 0.4.5, through the ols: adapter.

Terms the report names something else

These identifiers resolve, so nothing about them looks wrong, and the ontology calls them something unrelated to what the report calls them. That usually means the identifier is not the one the sentence needs:

• HP:0002451 (1 mention) - the report calls it "Limb ataxia — not stated"; HP calls it Limb dystonia

Obsolete terms

These terms are real but deprecated. Citing one is not a fabrication; it does mean the report is naming something the ontology has retired:

• GO:0006486 (obsolete protein glycosylation) (1 mention) - replaced by GO:0009101

Terms whose name is worth a second look

The report's name for these is recognisably related to the term's own name without being one of them. A loose paraphrase reads the same way as a citation of the wrong sibling term - and so does a related synonym, which the ontology records precisely because it names something adjacent rather than the same thing - so these are listed rather than judged:

• HP:0007266 (1 mention) - the report calls it "Diffuse cerebral atrophy"; HP calls it Cerebral dysmyelination
• HP:0007305 (1 mention) - the report calls it "Abnormality of the cerebral white matter"; HP calls it CNS demyelination, and lists "Demyelination in central white matter" among its other names
• GO:0006890 (1 mention) - the report calls it "retrograde vesicle-mediated transport, Golgi to ER — for BET1L's role"; GO calls it retrograde vesicle-mediated transport, Golgi to endoplasmic reticulum, and lists "retrograde vesicle-mediated transport, Golgi to ER" among its other names
• GO:0006486 (1 mention) - the report calls it "protein glycosylation"; GO calls it obsolete protein glycosylation