Arrhinia-choanal atresia-microphthalmia syndrome

Arrhinia-choanal atresia-microphthalmia syndrome (also known as Bosma arhinia microphthalmia syndrome, or BAMS) is an extremely rare congenital disorder characterized by the triad of arrhinia (complete absence of the nose), choanal atresia (blockage of the nasal passages), and microphthalmia (abnormally small eyes). This condition affects craniofacial development and the visual system, and may also involve abnormalities of the reproductive system, including hypogonadotropic hypogonadism, cryptorchidism in males, and absent or delayed puberty. Additional features can include a high-arched or cleft palate, absent paranasal sinuses, and absent or hypoplastic olfactory structures, leading to anosmia (absence of the sense of smell). The eyes may range from mildly small to severely underdeveloped (anophthalmia), and colobomas may be present. The syndrome has been linked to gain-of-function mutations in the SMCHD1 gene, which plays a role in epigenetic regulation and craniofacial development. Inheritance appears to follow an autosomal dominant pattern, though many cases arise de novo (as new mutations). Fewer than 100 cases have been reported in the medical literature worldwide. There is no cure for this condition. Management is supportive and multidisciplinary, involving craniofacial surgeons, ophthalmologists, endocrinologists, and otolaryngologists. Surgical interventions may be needed to address airway obstruction caused by choanal atresia, which can be life-threatening in neonates who are obligate nasal breathers. Prosthetic nasal reconstruction may be considered for cosmetic and functional purposes. Hormone replacement therapy may be required for individuals with hypogonadism. Ophthalmologic care is tailored to the degree of eye involvement.

Common questions about Arrhinia-choanal atresia-microphthalmia syndrome