| domain | established finding | quantitative evidence | suggested ontology terms | evidence type/source |
|---|---|---|---|---|
| Disease identity | Burn-McKeown syndrome is a rare congenital craniofacial spliceosomopathy; OMIM 608572 | Fewer than 20 affected families reported worldwide by 2020 (pqac-00000000, pqac-00000009) | OMIM: 608572; congenital disorder; craniofacial developmental disorder | Human disease synthesis and patient-derived model background (pqac-00000000, pqac-00000009) |
| Inheritance | Autosomal recessive disease caused by biallelic TXNL4A variants | 9 of 11 families in the discovery study had biallelic TXNL4A mutations (pqac-00000001, pqac-00000003) | autosomal recessive inheritance; TXNL4A | Human clinical genetics, AJHG 2014 (pqac-00000001, pqac-00000003) |
| Causal gene/mechanism class | TXNL4A encodes a U5 snRNP/spliceosome component; disease reflects reduced TXNL4A dosage rather than simple heterozygous haploinsufficiency | Unaffected heterozygous relatives carried single variants; disease required biallelic hypomorphic/LoF combinations (pqac-00000004) | TXNL4A; U5 snRNP; pre-mRNA splicing | Human genetics with functional interpretation (pqac-00000004) |
| Pathogenic variant architecture | Typical genotype is compound heterozygosity for a 34-bp promoter deletion on one allele plus a loss-of-function allele on the other; homozygous promoter deletion also reported | Promoter D1: chr18:g.77,748,581_77,748,614del; promoter D2: chr18:g.77,748,604_77,748,637del; LoF examples: c.349G>T p.(Glu117*), c.37C>T p.(Gln13*), c.131delT p.(Val44Alafs*48); terminal 18q deletions also observed (pqac-00000000, pqac-00000004) | TXNL4A; promoter deletion; nonsense variant; frameshift variant; copy-number loss | Human clinical genetics and molecular characterization (pqac-00000000, pqac-00000004) |
| Population genetics | The commonest disease-associated promoter allele is low frequency in the general population, consistent with a rare recessive disorder | Type 1 promoter deletion allele frequency 0.76%; predicted homozygous frequency ~1 in 17,300 (pqac-00000001, pqac-00000003) | low-frequency regulatory allele | Human case-control/segregation data (pqac-00000001, pqac-00000003) |
| Core phenotype | Choanal atresia/stenosis is the defining feature; reported synthesis states it was observed in all patients, with associated craniofacial, hearing, and occasional visceral anomalies | Choanal atresia observed in all patients in the 2020 synthesis; common additional features include hearing loss, cleft lip/palate, short palpebral fissures, lower eyelid coloboma, short philtrum, prominent nose/high bridge, large ears; congenital heart defects can occur (pqac-00000000, pqac-00000009) | choanal atresia; cleft palate; hearing impairment; eyelid coloboma; short philtrum; prominent nose; congenital heart defect | Human disease synthesis and original family series (pqac-00000000, pqac-00000009, pqac-00000019) |
| Additional variable features | Reported variable findings extend beyond the canonical craniofacial pattern | Patent foramen ovale, persistent ductus arteriosus, imperforate anus, fifth-finger clinodactyly, hallux valgus, preauricular tags, renal agenesis, inguinal hernia reported across families (pqac-00000002, pqac-00000018) | imperforate anus; clinodactyly; renal agenesis; preauricular tag | Human family series (pqac-00000002, pqac-00000018) |
| Neurodevelopment | Intellectual development is usually normal, but severe intellectual disability has been reported rarely | One exceptional severe intellectual disability case noted in the literature/model background (pqac-00000000, pqac-00000006) | intellectual disability | Human case-based synthesis and iPSC-study background (pqac-00000000, pqac-00000006) |
| Molecular pathophysiology upstream | Promoter deletions reduce TXNL4A expression; reduced TXNL4A impairs U4/U6.U5 tri-snRNP assembly | Type 1 and type 2 promoter deletions reduced promoter activity by 59% and 72%, respectively; yeast DIB1 depletion impaired tri-snRNP assembly (pqac-00000000, pqac-00000003) | TXNL4A; U4/U6.U5 tri-snRNP assembly; mRNA splicing | Human regulatory assay plus yeast functional model (pqac-00000000, pqac-00000003) |
| Molecular pathophysiology downstream | Reduced TXNL4A causes selective mis-splicing and altered gene expression, especially in neural crest-relevant programs | In patient iPSCs: 1,511 alternative splicing events in 1,096 genes and 1,181 DEGs; in iNCCs: 2,991 splicing events in 2,029 genes and 5,746 DEGs, with 88% of differential splicing unique to iNCCs (pqac-00000008, pqac-00000010, pqac-00000013) | alternative splicing; gene expression regulation; neural crest development | Human patient-derived iPSC/iNCC transcriptomics (preprint) (pqac-00000008, pqac-00000010, pqac-00000013) |
| WNT/neural crest mechanism | A leading mechanistic model links TXNL4A deficiency to dampened WNT signaling via TCF7L2 mis-splicing, delaying neural crest epithelial-to-mesenchymal transition | Patient iNCC EMT score -5 vs +5 (mother) and +8 (controls); AXIN2 downregulated (p=0.0004); TCF7L2 exon 4 mis-splicing validated; patient iPSCs proliferated 52%-65% more slowly than controls/mother (pqac-00000007, pqac-00000010, pqac-00000011) | WNT signaling; TCF7L2; epithelial to mesenchymal transition; neural crest cell | Human patient-derived iPSC/iNCC functional model (preprint) (pqac-00000007, pqac-00000010, pqac-00000011) |
| Developmental cell biology | Neural crest depletion/dysfunction is supported across models as a proximate cause of craniofacial malformation | Xenopus Txnl4a knockdown increased apoptosis in dorsal ectoderm at stage 15 (n=41, p<0.0005) and produced craniofacial cartilage defects in 38% of tadpoles; sox10 reduction was partially rescued by morpholino-resistant txnl4a (pqac-00000014, pqac-00000015, pqac-00000017) | neural crest cell; apoptosis; craniofacial cartilage development; sox10 | Xenopus morpholino/rescue model (pqac-00000014, pqac-00000015, pqac-00000017) |
| Onset/course | Disease onset is congenital/developmental and non-remitting; manifestations arise from embryonic craniofacial development defects | Choanal atresia and craniofacial anomalies are present from birth; no evidence for episodic course or spontaneous remission (pqac-00000000, pqac-00000019) | congenital onset; craniofacial malformation | Human clinical description/synthesis (pqac-00000000, pqac-00000019) |
| Diagnostic strategy | Diagnosis is clinical plus molecular: recognize the choanal-atresia/facial dysostosis pattern, then confirm biallelic TXNL4A variants including regulatory deletion and CNV detection | Discovery study used exome/genome sequencing, microarray, and MLPA; CNVs ranged from 0.484 Mb to 4.7 Mb; promoter deletions would be missed by coding-only analysis if regulatory regions are not interrogated (pqac-00000002, pqac-00000004) | facial dysostosis; TXNL4A molecular testing; copy-number analysis; promoter variant analysis | Human genetics workflow evidence (pqac-00000002, pqac-00000004) |
| Management | No disease-modifying BMKS therapy is established; care is supportive and anomaly-directed | No BMKS-specific interventional trials identified; reported care needs include airway management for choanal atresia, hearing support including possible cochlear implantation, and management of cleft/cardiac/other anomalies as indicated (pqac-00000018) | supportive care; surgical repair; hearing rehabilitation | Human case series plus evidence gap on trials (pqac-00000018) |
| Prognosis/evidence gaps | Prognosis is poorly quantified because of the rarity of the condition; survival, QoL, and natural-history metrics are not well defined in the literature retrieved | No robust prevalence, incidence, survival, or treatment-response statistics identified beyond family counts and phenotype summaries (pqac-00000000, pqac-00000019) | rare disease epidemiology | Evidence-gap synthesis from available literature (pqac-00000000, pqac-00000019) |
| Model systems | BMKS has mechanistic models in yeast, patient-derived iPSC/iNCC systems, and Xenopus embryos | Yeast DIB1 depletion showed tri-snRNP assembly defects; iPSC/iNCC model demonstrated proliferation, splicing, and EMT/WNT abnormalities; Xenopus knockdown caused neural crest/apoptosis/cartilage phenotypes with partial rescue (pqac-00000003, pqac-00000006, pqac-00000014) | Saccharomyces cerevisiae model; induced pluripotent stem cell; induced neural crest cell; Xenopus laevis | Yeast, in vitro human, and amphibian model evidence (pqac-00000003, pqac-00000006, pqac-00000014) |


*Table: This table condenses the main disease-level, genetic, mechanistic, diagnostic, and model-system findings for Burn-McKeown syndrome. It highlights established evidence and key quantitative details while preserving citations to the retrieved source contexts.*