Novel mutations cause biotinidase deficiency in Turkish children

Mutation analysis was performed on DNA from 31 Turkish children with profou nd biotinidase deficiency who were symptomatic or ascertained by newborn sc reening. The 98G:del7ins3 mutation is common in clinically ascertained chil dren in both the United States and Turkish populations, but a unique common mutation, R79C, is found only in the Turkish children identified both clin ically and by newborn screening. Another frequently occurring mutation, T53 2M, is only observed in the Turkish newborn screening group. There are four other less frequent novel mutations identified in the Turkish population. Interestingly, the Q456H and the A171T:D444H double mutation, which are the most common mutations found in the US newborn screening population and hav e not been observed in symptomatic children, do occur in clinically ascerta ined children in the Turkish population, although the double mutation may b e associated with milder and/or later-onset symptoms.