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H.M. Vastinsalo, J. Isosomppi, E.–M. Sankila; Two Novel Mutations in Myosin VIIA Cause USH1B in a Compound Heterozygote Finnish Patient . Invest. Ophthalmol. Vis. Sci. 2005;46(13):1800.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To investigate the molecular background of the disease of a four–year–old patient with sensory neural bilateral deafness, history of late walking, early manifestations of retinitis pigmentosa (RP), and normal connexin 26 gene. Methods: Genomic DNA was extracted from the patient’s and the family members’ blood samples and MYO7A exons were directly sequenced. The two found mutations were detected from 100 unrelated Finnish control samples by restriction enzyme digestion. Results: The patient was found to be a compound heterozygote for two novel MYO7A mutations. The mutation c.2766–2779 del 14nt is a truncating mutation (K922fsX930) located in the coiled coil region of MYO7A. A single nucleotide change c.5686C>T (Q1896X) is also a truncating mutation, abolishing part of the C–terminal FERM–domain of MYO7A. The parents were healthy heterozygous carriers of their respective mutations. The deletion mutation was found from one healthy heterozygous Finnish control. Studies of the prevalence of these mutations in the Finnish Usher population are ongoing. Conclusions: We present two novel MYO7A mutations resulting in premature termination of translation. The putative protein products lack the functional C–terminal tails responsible for specific binding. The novel mutations are similar to other mutations known to cause USH1B. Deafness together with the early symptoms of RP in our patient suggest that also these new mutations cause USH1B.
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