IS THERE A GENETIC-BASIS FOR GESTATIONAL DIABETES

Rh E-PGM1 (phosphoglucomutase locus 1) joint genotype frequencies (chr omosome 1) have been determined in 90 women with gestational diabetes mellitus (GDM) and in 140 pregnant women with preexisting insulin-depe ndent diabetes mellitus (IDDM) and non-insulin-dependent diabetes mell itus (NIDDM). The pattern of Rh E-PGM1 association differs among types of diabetes. The distortion of the pattern tends to assume opposite v alues in GDM and NIDDM and this is particularly evident in PGM12,2 su bjects. The proportion of PGM12,2 subjects homozygous for the Rh e al lele is higher in GDM than in IDDM and NIDDM. IDDM women show an inter mediate proportion and NIDDM women show the lowest proportion of this genotype. The opposite pattern is observed among PGM12,2 subjects car rying the Rh E allele. Genotype frequencies of the hypervariable regio n flanking the insulin gene (chromosome 11) have been determined in 77 women with GDM, in 52 pregnant women with preexisting diabetes (IDDM and NIDDM), and in 62 normal adults. In GDM and NIDDM subjects the fre quencies are similar. In IDDM women the frequency of homozygotes for t he class 1 allele is higher than the frequency found in GDM and NIDDM women. The data suggest a possible genetic basis for the differentiati on of a subclass of GDM from both IDDM and NIDDM.