Identification of an uncommon haptoglobin type using DNA and protein analysis.
The inherited variations in haptoglobin phenotypes are attributed to the homozygous and heterozygous combinations of three common autosomal alleles: HP*1F, HP*1S and HP*2. HP*1F and HP*1S encode polypeptides that differ by two amino acids at positions 51 and 53. The formation of HP*2 is postulated to have resulted from a breakage and subsequent reunion event at non-homologous positions of two HP*1 alleles. The most common form of HP*2 is HP*2FS in which the 5' end of HP*2 resembles HP*1F and the 3' end resembles HP*1S. Homologous crossing over between HP*2 and either an HP*1F or HP*1S allele in HP*2/HP*1 heterozygotes can change the usual type of HP*2 to three other forms: HP*2SS, HP*2FF or HP*2SF. We describe a nuclear family in which the uncommon genotype HP*2SS is one parent caused initial confusion in assigning genotypes to the rest of the nuclear family. The data demonstrate the need for a cautious approach when deducing haptoglobin genotypes from molecular analysis alone.
Marles
S L
SL
Department of Pediatrics and Child Health, University of Manitoba, Winnipeg, Canada.
McAlpine
P J
PJ
Zelinski
T
T
Phillips
S
S
Maeda
N
N
Greenberg
C R
CR
D000483:Alleles; D001798:Blood Proteins / Q000032:analysis*; D015139:Blotting, Southern; D003317:Corneal Dystrophies, Hereditary / Q000235:genetics; D004247:DNA / Q000032:analysis*; D004592:Electrophoresis, Starch Gel; D005260:Female; D005838:Genotype; D006242:Haptoglobins / Q000235:genetics*; D006801:Humans; D008297:Male; D009693:Nucleic Acid Hybridization; D010641:Phenotype
D001798:Blood Proteins; D006242:Haptoglobins; D004247:DNA