In our study the finding that female babies comprised 36% of the G--6-PD deficient population is not unusual. A similar proportion was seen in studies in Delhi (30.7%) and Ludhiana (35.8%)(1,2), and another report(3) found that 56% of G-6-PD deficient patients were females. G-6-PD deficiency represents one of the best studied examples of human genetic polymorphism. In 1962, families with G-6-PD deficiency with genetic transmission aberrant for X-linkage were observed(4) leading to the suggestion that one of the two X-chromosomes might be inactive in human females; this was independent of the proposal made by Lyon on the basis of X-linked traits in mice(5). Thus female infants are affected because they have two populations of erythrocytes, one with normal and one with low levels of G-6-PD, in keeping with the Lyon hypothesis. In populations where the gene frequency is high or consanguineous marriages are common, it is also possible for a female infant to be homozygous for the deficiency.
 

Atanu Kumar Jana,
Professor and Head,
Neonatology Department,
Christian Medical College and Hospital,
Vellore 632 004,
India.

 

1. Madan N, Sundaram KR, Bhargava SK, Sood SK. G6PD deficiency and neonatal hyperbilirubinemia. Indian J Med Res 1989; 90: 306-313.

2. Verma M, Singla D, Crowell SB. G6PD deficiency in neonates: A prospective study. Indian J Pediatr 1990; 57: 385-388.

3. Dutta RN, Majid J, Hasan MI, Choksey NJ. G6PD deficiency in newborn infants. J Indian Med Assoc 1968; 51: 315-319.

4. Beutler E, Yeh M, Fairbanks VF. The normal human female as a mosaic of X-chromosome activity: Studies using the gene for G6PD deficiency as a marker. Proc Natl Acad Sci USA 1962; 48: 9-14.

5. Lyon MF. Gene action in the X-chromosome of the mouse (mus musculus 1.) Nature 1961; 190: 372-376.