First demonstration of recombination between the gene for Norrie disease and probe L1.28.

Norrie disease is an X-linked trait thought to be tightly linked to the anonymous probe L1.28. Here we report the first recombinational event among 24 informative meioses. This indicates there is a 4% (95% C.L. 0.1%-21%) error rate introduced by meiotic crossovers in carrier or prenatal diagnosis based on linkage between Norrie disease and L1.28.