Unilateral posterior subcapsular cataract and lenticonus in a girl with Bloom's syndrome - report of a rare case.

Background: Bloom's syndrome (BS) a rare, autosomal recessive disorder is a genodermatosis characterized by prenatal and postnatal growth deficiency, photosensitive skin changes, immune deficiency, insulin resistance, and a greatly increased risk of early cancer. Loss-of-function mutations of BLM gene, which codes for a RecQ helicase, cause Bloom's syndrome. The absence of a functional BLM protein causes chromosome 10 instability, excessive homologous recombination, and a greatly increased number of sister chromatid exchanges that are pathognomonic for the syndrome.