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Two highly penetrant loci have been linked to familial breast cancer (BRCA1 and BRCA2), but do not explain most breast cancer familial aggregation. A new study suggests that a variant in a gene involved in DNA repair may account for some of this unexplained risk.
The position of trinucleotide repeats relative to adjacent origins of DNA replication can drastically affect repeat expansion. This finding offers insight into the cause of several hereditary diseases in humans.
The recent characterization of the alcohol* dehydrogenase Aldh1a2 and the cytochrome P450 Cyp26, two enzymes involved in retinoid metabolism, has helped to explain how bioactive retinoids are made and catabolized. By the elegant definition of an Aldh1a2 null mutation as a dominant suppressor of a Cyp26 null mutation, it is now unequivocally demonstrated that the main function of Cyp26 is to degrade endogenous all-trans retinoic acid rather than to synthesize bioactive hydroxylated retinoids.
The relative contribution of mothers and fathers to mutation can be studied by evolutionary analysis of sex-linked DNA sequences. A new study shows that mutations occur in men at a rate five times of that in women, lending support to the idea of 'male-driven evolution'.
Nonsyndromic Hirschsprung disease, hitherto assumed to be a multifactorial disease with a threshold effect due to an unknown number of genes, has been genetically dissected and shown to result from an interaction between just three loci, two of which have not previously been associated with the disease. Oligogenic inheritance can explain the main aspects of its genetic epidemiology.