Abstract
Purpose:
To report a familial case of Tietz syndrome (TS) caused by a novel MITF mutation and nanophthalmos.
Methods:
Affected patients underwent a complete ocular and systemic examination. In addition, B scan echography was performed. Molecular studies included PCR amplification and automated DNA sequencing of the complete MITF coding sequence.
Results:
The propositus is an 11 years old boy with severe congenital deafness and cutaneous, hair and ocular hypopigmentation. No nystagmus, iris transillumination, or foveal hypoplasia were seen. Refraction was +11= -7.00 x 175° (OD) and +12=-6.50x0° (OS). His mother has a similar phenotype with deafness, hypopigmentation and high hyperopia and his brother has hypopigmentation but not deafness. A B scan echography showed an anterior posterior axial length of 19.47mm for OD and 19.70mm for OS. MITF gene analysis disclosed a novel c.216A>C heterozygous mutation in exon 8.
Conclusions:
TS is an autosomal dominant condition characterized by albinoid-like hypopigmentation of the skin and hair and severe hearing loss. The disorder is caused by mutations in MITF, a gene encoding a basic helix-loop-helix leucine zipper transcription factor, which regulates melanocyte development and the biosynthetic melanin pathway. TS is a rare entity that should be differentiated from oculocutaneous albinism. In addition to the typical abnormalities of the syndrome, nanophthalmos was observed in the case described here. Interestingly, Mitf mutation in mice causes microphthalmia. Our results expand both the clinical and molecular spectrum of TS.
Keywords: 539 genetics •
547 hyperopia •
585 macula/fovea