Recessive congenital methemoglobinemia in immediate generations.

We report herein on our observation of recessive congenital methemoglobinemia (type I), an autosomal recessive disorder, in immediate generations (in a mother and her daughter). Molecular analysis revealed a mechanism of inheritance not reported previously, despite the high probability of occurrence in autosomal recessive disorders. This report is also the first publication describing an extremely rare mutation (Arg50Gln) causing this disorder in the Turkish population.