HPA were the most common diseases (75/209, 35.9%, 1:4580), followed by phenylketonuria (PKU) (32/209, 15.3%, 1:10,735), classical homocystinuria due to cystathionine beta synthase deficiency (CBS) (3/209, 1.4%, 1:114,502), and MTHFR defects (1/209, 0.5%, 1:343,507). The gene discussed is MTHFR; the disease is phenylketonuria.