Low prevalence of p.G352fsdelG mutation in phenylketonuria patients from Morocco

Frameshift mutation p.G352fsdelG in the PAH gene was recently reported as the most common mutation in Moroccan patients with phenylketonuria (PKU). This result, if confirmed, would considerably facilitate genetic counseling and molecular diagnosis of the disease in Morocco. Given that the incidence of PKU in the Mediterranean region is estimated at between 1/4000 and 1/10,000, this mutation would be harbored by many Moroccans. We aimed to estimate the frequency of heterozygotes for the p.G352fsdelG mutation in Moroccan newborns. In this study, we used a reliable TaqMan(®) real-time polymerase chain reaction to detect the mutation p.G352fsdelG in the PAH gene in 250 unrelated Moroccan newborns. DNA was extracted from umbilical cord blood with maternal consent. The supposed recurrent mutation p.G352fsdelG was found in none of the 250 tested newborns. Therefore, the frequency of heterozygotes for this mutation would be less than 1/250, and the incidence of patients with PKU homozygous for this mutation would not exceed 1/100,000. The p.G352fsdelG mutation in the PAH gene does not appear to be prevalent in the Moroccan population and would be responsible for only few cases of PKU. The previous report of this anomaly as being responsible for 62.5% of PKU patients in Morocco could be explained by selection bias.