An unusual form of galactosemia: studies on erythrocytes and hair roots.
An unusual form of galactosemia is described in a 7-month-old boy, characterized by a late onset of the clinical symptoms. A high apparent residual activity of erythrocyte galactose-1-phosphate uridyl transferase (GT) was measured with the spectrophotometric UDP-Glucose consumption test(+/-25% of normal). The residual activity in erythrocyte lysates, determined when the patient was 7, 16 and 22 months old, significantly decreased upon storage and after preincubation with NAD-ase. The radiochemical measurement of GT activity demonstrated a severe deficiency: only a level of +/-1% of normal activity was observed, and no effects of storage or NAD-ase could be demonstrated. GT and galactokinase (GK) activities were measured radiochemically in lysates from hair roots obtained from the human scalp, and it was found that the GT/GK activity ratio is a useful index for the detection of heterozygotes. Erythrocyte and hair root lysates from the heterozygous parents of the patient displayed GT/GK ratios which were intermediate between mutant and normal. Because they offer a simple and fast way to obtain biopsy material, hair roots might become of increasing importance for carrier detection studies.
D000328:Adult; D004912:Erythrocytes / Q000201:enzymology*; D005260:Female; D005693:Galactosemias / Q000201:enzymology* / Q000235:genetics; D006197:Hair / Q000201:enzymology*; D006579:Heterozygote; D006801:Humans; D007223:Infant; D008297:Male; D009244:NAD+ Nucleosidase / Q000097:blood*; D009713:Nucleotidyltransferases / Q000097:blood* / Q000378:metabolism*; D010770:Phosphotransferases / Q000235:genetics / Q000378:metabolism*; D013053:Spectrophotometry; D005694:UTP-Hexose-1-Phosphate Uridylyltransferase / Q000097:blood* / Q000235:genetics / Q000378:metabolism*
D010770:Phosphotransferases; D009713:Nucleotidyltransferases; D005694:UTP-Hexose-1-Phosphate Uridylyltransferase; D009244:NAD+ Nucleosidase