Haploinsufficiency of SF3B2 revealed by a craniofacial microsomia with atypical presentation: a case report

Otomandibular syndrome is primarily characterised by craniofacial microsomia (CFM). Pathogenic loss-of-function variants of the SF3B2 gene, which encodes the U2 subunit of the spliceosome, can cause CFM through a haploinsufficiency mechanism. This study aims to present the clinical phenotype and maxillofacial management of a patient carrying a novel SF3B2 gene variant. We present the case of a patient with a heterozygous de novo pathogenic variant of the SF3B2 gene who presented with an otomandibular syndrome accompanied by progressive camptodactyly of the extremities, which had not been described previously. Particularly low maxillary and mandibular bone density was observed during bimaxillary osteotomy, necessitating adaptation of the surgical protocol. This case expands the phenotypic spectrum of anomalies associated with the SF3B2 gene by indicating potential subclinical acral and bone involvement. It also emphasises the importance of genetic analysis in complex craniofacial malformations.