A Caucasian Family with the i Phenotype and Congenital Cataracts

Macdonald, E.B.; Douglas, R.; Harden, P.

doi:10.1111/j.1423-0410.1983.tb04490.x

Cited by 17 publications

(6 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The association does not seem to be as pronounced in the white population, however, with only 3 individuals in 2 families formally reported as having both the adult i phenotype and congenital cataracts. [24][25][26] The association of the adult i phenotype with congenital cataracts can be explained either by a close linkage between independent I-and cataract-related genes or by a pleiotropic effect of the gene responsible for the adult i phenotype on the development of cataracts. However, because of the reduced strength of the association in whites, it has been suggested that the former hypothesis of a close linkage between 2 independent genes is the more tenable one.…”

Section: Introductionmentioning

confidence: 99%

The molecular genetics of the human I locus and molecular background explain the partial association of the adult i phenotype with congenital cataracts

Twu

Chou

et al. 2003

Blood

104

View full text Add to dashboard Cite

The human i and I antigens are characterized as linear and branched repeats of N-acetyllactosamine, respectively. Conversion of the i to the I structure requires I-branching beta-1,6-N-acetylglucosaminyltransferase activity. It has been noted that the null phenotype of I, the adult i phenotype, is associated with congenital cataracts in Asians. Previously, the identification of molecular changes in the IGnT gene, associated with the adult i phenotype, has been reported. In the present study, we demonstrate that the human I locus expresses 3 IGnT forms, designated IGnTA, IGnTB, and IGnTC, which have different exon 1, but identical exons 2 and 3, coding regions. The molecular genetics proposed for the I locus offer a new perspective on the formation and expression of the I antigen in different cells and provide insight into the questions derived from investigation of the adult i phenotype. Molecular genetic analyses of the I loci of the 2 adult i groups, with and without congenital cataracts, were performed, and enzyme function assays and expression patterns for the 3 IGnT transcripts in reticulocytes and lens-epithelium cells were analyzed. The results suggest a molecular genetic mechanism that may explain the partial association of the adult i phenotype with congenital cataracts and indicate that a defect in the I locus may lead directly to the development of congenital cataracts. The results also suggest that the human blood group I gene should be reassigned to the IGnTC form, not the IGnTB form, as described previously.

show abstract

Section: Introductionmentioning

confidence: 99%

The molecular genetics of the human I locus and molecular background explain the partial association of the adult i phenotype with congenital cataracts

Twu

Chou

et al. 2003

Blood

104

View full text Add to dashboard Cite

show abstract

“…Autosomal recessive inheritance of congenital cataracts is rare, although there have been some cases reported (Francois et al 1982;Macdonald et al 1983;Shokeir and Lowry 1985;Forsius et al 1992;Ippel et al 1994). Yamagucho presented evidence suggesting the linkage of Iiblood group located at 9q21 (Bierhuizen et al 1993) with a recessive form of congenital cataracts, and this linkage was confirmed later by Ogata et al (1979).…”

Section: Genetic Linkage Of Congenital Cataractsmentioning

confidence: 92%

Congenital cataracts: gene mapping

2000

Human Genetics

View full text Add to dashboard Cite

show abstract

“…2,11 In certain kindreds, i adult is associated with congenital cataracts. [12][13][14] Based on older serologic studies, the incidence of i adult ranges from 1 in 4400 to 1 in 17,000. 1,15 The prevalence of mutant IGnT alleles in the general population is unknown but is presumably rare.…”

Section: Systemmentioning

confidence: 99%

“…Subsequent studies by other investigators, however, were conflicting, indicating that the i adult phenotype did not always predispose to congenital cataracts, particularly in non-Asian populations. 13,14 The apparent discrepancy was finally resolved with cloning of the IGnT gene, 38 followed by sequencing analysis of i adult individuals. 7-10 As already described, the i adult phenotype without cataracts is the consequence of mutations affecting exon E1C, leading to an isolated loss of IGnT activity in erythroid cells (Table 2, Fig.…”

Section: Cataractsmentioning

confidence: 99%