Researchers at the National Eye Institute have identified the gene responsible for a newly recognized syndrome that causes coloboma and microphthalmia.
The syndrome is called COMMAD, an acronym for the conditions it causes: coloboma, osteopetrosis, microphthalmia, macrocephaly, albinism and deafness. It affects children who inherit 2 mutations of a gene, one from each parent, who are deaf due to another rare, genetic disorder called Waardenburg syndrome 2A. The first 2 recognized cases of COMMAD are documented in the December issue of the American Journal of Human Genetics.
The identification of COMMAD and its genetic cause is important because intermarriage within the deaf community is relatively common, and people who are deaf may not know that their deafness is associated with Waardenburg 2A.
Most Americans born deaf do not have Waardenburg syndrome 2A, which, in addition to hearing loss, is associated with premature graying of the hair, blue eyes, fair skin and sometimes vision problems. A comprehensive dilated eye exam may detect eye abnormalities that suggest the need for genetic testing to rule out Waardenburg 2A.
Both children described in the paper had inherited from each parent mutated versions of a gene called microphthalmia-associated transcription factor (MITF). Both children are blind.
Future research is needed to understand the role of MITF during early development, and how mutations in this gene result in the development of Waardenburg syndrome 2A or COMMAD, writes the paper’s lead author, Brian P. Brooks, MD, PhD, NEI clinical director and chief of the Pediatric, Developmental, and Genetic Ophthalmology Section.