A novel IGnT allele responsible for the adult i phenotype
Resource
Transfusion 46 (11): 1982-1987
Journal
Transfusion
Journal Volume
46
Journal Issue
11
Pages
1982-1987
Date Issued
2006
Date
2006
Author(s)
Abstract
BACKGROUND: The adult i phenotype has been characterized as the presence of a very low level of I antigen but a high quantity of I antigen on red blood cells (RBCs). It has been noted that this rare phenotype is partially associated with congenital cataracts. It has been demonstrated that the human I locus expresses three IGnT forms, IGnTA, IGnTB, and IGnTC, and that the IGnTC gene is responsible for the I antigen expression on RBCs. This report describes molecular genetic analysis of a Taiwanese person with the adult i phenotype but without congenital cataracts. STUDY DESIGN AND METHODS: The five exon regions of the IGnT gene of the adult i individual were amplified by polymerase chain reaction (PCR) and cloned, and the sequences were determined. The activity of the IGnT enzyme expressed from the mutant IGnTC gene identified in this i adult was analyzed. RESULTS: The presented adult i individual possesses wild-type IGnTA and IGnTB genes but a mutant IGnTC gene with a 243T>A nucleotide substitution, which predicts an amino acid alteration of Asn81Lys. PCR-restriction fragment length polymorphism analysis has been used to show that this IGnTC*243A allele is uncommon in the general Taiwanese population. The activity of the IGnT enzyme expressed from the mutant IGnTC*243A gene was significantly reduced when compared with that expressed from the wild-type IGnTC gene. CONCLUSION: A novel IGnTC allele with a 243T>A missense mutation was demonstrated in our adult i Taiwanese without congenital cataracts. The molecular basis revealed for this adult i case agrees with the proposed molecular genetic mechanism, accounting for the partial association of the adult i phenotype with congenital cataracts. © 2006 American Association of Blood Banks.
Other Subjects
beta 1,6 acetylglucosaminyltransferase; blood group I antigen; n acetylglucosaminyltransferase; unclassified drug; allele; article; congenital cataract; controlled study; enzyme activity; erythrocyte; exon; gene; gene amplification; gene locus; gene sequence; human; ignta gene; igntb gene; igntc gene; missense mutation; molecular cloning; molecular genetics; mutant; phenotype; polymerase chain reaction; protein expression; restriction fragment length polymorphism; Adult; Alleles; Amino Acid Substitution; Asian Continental Ancestry Group; Cataract; Female; Gene Expression; Humans; I Blood-Group System; Isoenzymes; Male; Mutation, Missense; N-Acetylglucosaminyltransferases; Phenotype; Polymerase Chain Reaction; Polymorphism, Restriction Fragment Length; Taiwan
Type
journal article
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