Type I GSD is autosomal recessive. The gene for glucose-6-phosphatase (G6PC; OMIM 23220) is located on chromosome 17q21, spans 12.5 kb, and has five coding exons. The gene for glucose-6-phosphate translocase (G6PT1; OMIM 23220) is located on chromosome 11q23 and consists of nine exons. Both types of GSD I are genetically heterogeneous. More than 73 disease-causing mutations are known for type Ia. Some ethnic group-specific and more frequently detected mutations for type Ia—R83C (Jewish), 130X (Hispanic), 35X, G188R, and Q347X (Caucasian), R83H (Chinese), 727 G>T (Japanese)—are responsible for about 78% of the known disease alleles.[9,10]

For GSD Ib, there are about 66 disease-causing mutations known. Two mutations, G339C and 1211delCT, appear to be more prevalent in Caucasian patients, whereas W118R appears to be common among Japanese patients.[10,11] Definitive genotype/phenotype correlation is not apparent for either subtype; however, GSD Ia mutations, 727G>A and G188R, confer specific pheno-types in affected patients when expressed in homozygous state (increased risk for hepatocellular carcinoma and recurrent infections and neutropenia, respectively). Identification of mutations allows prenatal diagnosis of both subtypes.[10,11]

Getting Started With Dumbbells

Getting Started With Dumbbells

The use of dumbbells gives you a much more comprehensive strengthening effect because the workout engages your stabilizer muscles, in addition to the muscle you may be pin-pointing. Without all of the belts and artificial stabilizers of a machine, you also engage your core muscles, which are your body's natural stabilizers.

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