This SNP is supposed to serve as a marker for the Q318X null allele of the 21-hydroxylase gene. This would generally be associated, when homozygous, with the most severe form of congenital adrenal hyperplasia (salt wasting). However, a random survey of 10 publicly uploaded genomes showed all 10 to be carriers. This is well out of Hardy-Weinberg equilibrium, making the accuracy of this SNP as reported by 23andme suspect. Positive results should be clinically correlated and verified in cooperation with your health care provider.