Glucose-6-phosphate dehydrogenase deficiency: molecular heterogeneity in southeast Asian countries.

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is common in malaria endemic regions and is estimated to affect more than 400 million people worldwide. Deficient subjects are mostly asymptomatic but clinical manifestations range from neonatal jaundice due to acute hemolytic anemia to chronic non-spherocytic hemolytic anemia. To date, biochemical parameters allowed more than 400 different G6PD variants to be distinguished thereby suggesting a vast genetic heterogeneity. So far, only a small portion of this heterogeneity has been confirmed at the DNA level with the identification of about 90 different point mutations in the G6PD coding sequence. To determine the molecular background of G6PD deficiency in Southeast Asian countries, we conducted molecular analyses of G6PD patients from the Philippines, Malaysia, Singapore, Vietnam and Indonesia. The most prevalent mutation identified differs from country to country, thus suggesting independent mutational events of the G6PD gene.

Newborn screening in the Philippines.

The Newborn Screening Study Group first introduced newborn screening in the Philippines in 1996. This group of pediatricians and obstetricians from 24 hospitals in the metropolitan Manila area developed a newborn screening program: (1) to establish the incidence of six metabolic conditions--congenital hypothyroidism, congenital adrenal hyperplasia, galactosemia, phenylketonuria, homocystinuria and glucose-6-phosphate dehydrogenase deficiency, and (2) to make recommendations for the adoption of newborn screening nationwide. Newborn screening developed in three phases: (1) routine screening for 5 disorders excluding G6PD deficiency in the 24 member hospitals in Metro Manila, (2) addition of screening for G6PD deficiency to the 5-disorder screening panel, and (3) program evaluation with subsequent reduction in the time of sample collection to 24 hrs of age or older (from the initial requirement of 48 hrs. or older) and discontinuation of screening for homocystinuria as a cost cutting measure (due to non-detection of cases). Data from 201 participating hospitals reported in September 2001 confirmed 48 cases of congenital hypothyroidism, 21 cases of congenital adrenal hyperplasia, 2 cases of galactosemia, 4 cases of hyperphenylalanemia and 1,495 cases of glucose-6-phosphate dehydrogenase deficiency. The Department of Health has recognized the significance of the initial data and efforts are now being undertaken to ensure the nationwide implementation of newborn screening.