| Category | Summary |
|---|---|
| Disease | Mandibulofacial dysostosis with microcephaly (MFDM), also called mandibulofacial dysostosis-microcephaly syndrome / Guion-Almeida type (pqac-00000000, pqac-00000003, pqac-00000007) |
| Identifiers | MONDO: MONDO_0012516; OMIM: 610536 (pqac-00000000, pqac-00000001, pqac-00000007) |
| Causal gene | EFTUD2 (elongation factor Tu GTP binding domain containing 2), encoding the U5-116 kD spliceosomal GTPase (pqac-00000000, pqac-00000001, pqac-00000003, pqac-00000004) |
| Inheritance | Autosomal dominant; most reported cases are de novo heterozygous loss-of-function variants or deletions consistent with haploinsufficiency (pqac-00000003, pqac-00000004, pqac-00000005, pqac-00000006) |
| Variant spectrum | Deletions, frameshift, nonsense, splice-site, missense, start-loss, and synonymous splice-disrupting variants have been reported (pqac-00000004, pqac-00000005) |
| Core craniofacial features | Mandibular and maxillary hypoplasia, micrognathia, microtia/external ear anomalies, choanal atresia, cleft palate, characteristic dysmorphism (pqac-00000002, pqac-00000003, pqac-00000005, pqac-00000006, pqac-00000007) |
| Neurodevelopmental features | Microcephaly, developmental delay / intellectual disability, delayed psychomotor milestones; microcephaly may be congenital or postnatal and can become severe/progressive (pqac-00000002, pqac-00000003, pqac-00000004) |
| Quantitative clinical findings | Choanal/aural atresia, cleft palate, and congenital heart defects each reported in >50% of affected individuals in the original 12-person cohort; hearing loss in 10/12; head circumference eventually 3–6 SD below the mean in severe/progressive cases (pqac-00000003, pqac-00000005) |
| Extracranial findings | Esophageal atresia ~40%, congenital heart disease ~40%, thumb abnormalities ~25%, short stature in ~1/3; feeding/airway problems and abnormal brain myelination/white matter changes also reported (pqac-00000004, pqac-00000006) |
| Diagnostic approach | Clinical suspicion based on craniofacial pattern plus microcephaly/developmental delay; molecular confirmation by WES/WGS or trio exome; Sanger confirmation; RNA studies/minigene assays for splice variants; aCGH/CMA can detect pathogenic EFTUD2 deletions and has been proposed as a first-tier test in some congenital presentations (pqac-00000001, pqac-00000004, pqac-00000006, pqac-00000007) |
| Differential diagnosis clues | Phenotypic overlap with Treacher Collins syndrome, Nager syndrome, oculoauriculovertebral spectrum, and atypical CHARGE syndrome can delay diagnosis (pqac-00000001, pqac-00000007) |
| Mechanistic chain | EFTUD2 haploinsufficiency → impaired U5 spliceosome function / transcriptome-wide splicing defects → increased exon skipping including Mdm2 exon 3 skipping → p53 stabilization/activation → apoptosis of neural crest and neural progenitor cells → depletion of craniofacial precursor cells → craniofacial malformations and microcephaly (pqac-00000009, pqac-00000010, pqac-00000011, pqac-00000012, pqac-00000013, pqac-00000016) |
| Affected developmental cell populations | Cranial neural crest cells and neural progenitors are the best-supported vulnerable populations in model systems (pqac-00000008, pqac-00000009, pqac-00000010, pqac-00000013) |
| Model-organism evidence | Zebrafish eftud2 mutants show abnormal brain development and p53-dependent apoptosis; neural-crest-specific mouse Eftud2 loss causes brain/craniofacial malformations and prenatal lethality; Xenopus knockdown supports a neural crest/craniofacial developmental requirement (pqac-00000008, pqac-00000011, pqac-00000012, pqac-00000013) |
| Rescue evidence | Pharmacologic p53 inhibition with pifithrin-α partially improved morphology in the mouse model: midbrain improvement in 3/11 treated mutants vs 0/41 untreated; first pharyngeal arch size increased significantly (p<0.05). However, Trp53 deletion reduced apoptosis without fully rescuing craniofacial defects or survival, indicating additional p53-independent mis-splicing mechanisms (pqac-00000009, pqac-00000010, pqac-00000013, pqac-00000014) |
| Current understanding | MFDM is best understood as an EFTUD2-related craniofacial spliceosomopathy with dominant loss-of-function, variable expressivity, and disease mechanisms centered on selective developmental vulnerability of cranial neural crest and neuroepithelial lineages (pqac-00000003, pqac-00000008, pqac-00000010, pqac-00000016) |


*Table: This table condenses the main identifiers, genetics, clinical spectrum, diagnostic approaches, and disease mechanism for EFTUD2-related mandibulofacial dysostosis with microcephaly. It is useful as a quick-reference scaffold for a fuller disease knowledge base entry.*