APPARENT HIGHER FREQUENCY OF PHENYLKETONURIA IN THE MEXICAN STATE OF JALISCO

The geographic origin of Mexican patients with phenylketonuria (PKU) i n Mexico City and in southern California was studied, Compared to pati ents with other metabolic disorders, patients with PKU were significan tly more likely to have originated from the Los Altos region of the st ate of Jalisco and its environs. The incidence of PKU among mentally r etarded students attending special education schools was found to be s ignificantly higher in Jalisco (particularly the Los Altos region) tha n in the neighboring state of Guanajuato (1.09% vs 0.3%). These result s strongly suggest a ''population of origin'' effect, the mutant allel e(s) having been introduced by the Spanish ancestors of the current po pulation. Our findings also support the addition of PKU to the neonata l screening program for this region of Mexico.