Selecting damaged sperm

Three human dysmorphic syndromes result from autososmal dominant mutations in three of the four fetal growth factor receptor genes. One of these—Apert syndrome—is caused by a mutation that arises solely in the paternal gene, with increasing frequency positively correlated with increasing age. In the August 1 Science, Anne Goriely and colleagues at the Weatherall Institute of Molecular Medicine report that a mutation at this site is selected for because it confers an advantage to the individual sperm, even though the result is harmful in the developing embryo (Science 301:643-646, August 1, 2003).

Goriely et al. used an enrichment technique whereby the nonmutant DNA sequence at the region of amino acid 755, normally a cytosine (755C), was cleaved by the restriction enzyme MboI, allowing polymerase chain reaction amplification of the mutant sequence followed by pyrosequencing for identification and quantitation. By comparing mutation levels on each of the two alleles using a...