Heterozygous mutations in the SF3B4 gene cause Nager type of acrofacial dysostosis, which is the typical form of a group of disorders collectively known as the acrofacial dysostoses. They are characterized by malformation of the craniofacial skeleton & the limbs.
The major facial features of the Nager type include downslanted palpebral fissures, midface retrusion, and micrognathia, the latter of which often requires the placement of a tracheostomy in early childhood.
Limb defects typically involve the anterior (radial) elements of the upper limbs and manifest as small or absent thumbs, triphalangeal thumbs, radial hypoplasia or aplasia, & radioulnar synostosis.
Phocomelia of the upper limbs & , occasionally, lower-limb defects have also been reported.
Loading suggestions...