HBA2 and phenylketonuria: The carrier frequencies were as follows: 4.38% (14/320) for the GJB2 gene for hereditary deafness; 3.75% (12/320) for the SLC26A4 gene for hereditary deafness; 4.06% (13/320) for the ATP7B gene for Wilson’s disease; 2.81% (9/320) for the CYP21A2 gene for congenital adrenal hyperplasia; 2.50% (8/320) for the SMN1 gene for spinal muscular atrophy; 2.50% (8/320) for the PAH gene for phenylketonuria; 1.56% (5/320) for the HBA1/HBA2 gene for alpha-thalassemia; 1.25% (4/320) for the MMACHC gene for methylmalonic acidemia; and the remaining four carrier frequencies were less than 1% (Table 1).