Two novel compound heterozygous HOXB1 variants in congenital facial palsy: A case report and a brief review of the literature.

Hereditary congenital facial palsy (HCFP) is a medical condition caused by dysfunction of the seventh cranial nerve. HCFP is characterized by feeding difficulties and dysmorphic features in the orofacial region. In some cases hearing loss, strabismus, limb malformations, and musculoskeletal defects may be associated. There are three types of HCFP: HCFP3 (OMIM 614744) results from autosomal recessive pathogenic variants in the HOXB1 gene, while HCFP1 and 2 (OMIM 601471, 604185) are autosomal dominant, genetically less defined conditions. We report on a case of congenital bilateral facial palsy due to two novel compound heterozygous variants in the HOXB1 gene, found by exome sequencing (ES), in a child with facial nerve axonal neuropathy without evidence of nerve hypoplasia on neuroimaging. The results of this report suggest that in individuals with congenital facial paralysis and preserved ocular motor skills, with or without facial nerve hypoplasia and with confirmed facial nerve axonal neuropathy, HOXB1 variants and therefore a diagnosis of HCFP3 should be primarily considered.