New ABO intron 1 variant alleles.

Unusual and discrepant ABO phenotypes are often due to genetic variants that lead to altered levels or activity of ABO transferases and consequently to altered expression of ABO antigens. This report describes eight genetic alterations found in 15 cases with reduced or undetectable expression of ABO antigens. Forward and reverse ABO grouping was performed by standard gel or tube methods. Adsorption-heat elution and saliva testing for H and A substances followed the AABB technical manual procedures. Genomic DNA extracted from whole blood was PCR-amplified to cover the entire ABO coding sequence, splice junctions, proximal promoter, and intron 1 enhancer. Amplification products were sequenced by next-generation or Sanger dideoxy methods, either directly or after cloning into a bacterial plasmid vector. Eight unreported alleles were found in the 15 cases analyzed. Alleles ABO*A(28+1C) and ABO*A(29-5G) harbor variants that alter the consensus sequence at the intron 1 donor and acceptor splice sites, respectively. The other alleles harbor variants that alter the consensus sequence at transcription factor-binding sites in the intron 1 enhancer: specifically, ABO*A(28+5792T), ABO*A(28+5859A), and ABO*A(28+5860G) at GATA-1 sites; ABO*B(28+5877T) and ABO*B(28+5878G) at a RUNX1 site; and ABO*A(28+5843A) at or near a C/EBP site. Molecular and serologic characterization of ABO alleles can help in their future identification and in the resolution of discrepancies.Unusual and discrepant ABO phenotypes are often due to genetic variants that lead to altered levels or activity of ABO transferases and consequently to altered expression of ABO antigens. This report describes eight genetic alterations found in 15 cases with reduced or undetectable expression of ABO antigens. Forward and reverse ABO grouping was performed by standard gel or tube methods. Adsorption-heat elution and saliva testing for H and A substances followed the AABB technical manual procedures. Genomic DNA extracted from whole blood was PCR-amplified to cover the entire ABO coding sequence, splice junctions, proximal promoter, and intron 1 enhancer. Amplification products were sequenced by next-generation or Sanger dideoxy methods, either directly or after cloning into a bacterial plasmid vector. Eight unreported alleles were found in the 15 cases analyzed. Alleles ABO*A(28+1C) and ABO*A(29­5G) harbor variants that alter the consensus sequence at the intron 1 donor and acceptor splice sites, respectively. The other alleles harbor variants that alter the consensus sequence at transcription factor­binding sites in the intron 1 enhancer: specifically, ABO*A(28+5792T), ABO*A(28+5859A), and ABO*A(28+5860G) at GATA-1 sites; ABO*B(28+5877T) and ABO*B(28+5878G) at a RUNX1 site; and ABO*A(28+5843A) at or near a C/EBP site. Molecular and serologic characterization of ABO alleles can help in their future identification and in the resolution of discrepancies.

Hereditary hyperferritinaemia cataract syndrome: does it exist in Switzerland?

Recent research in iron metabolism has revealed the existence of iron-responding elements in the 5'UTR of the mRNA of ferritin. Binding of these structures with iron-regulatory proteins regulates ferritin synthesis within the cell, according to the intracellular iron level. Several mutations of the iron-responding elements located at the 5'UTR of the L-ferritin subunit, which lead to the hereditary hyperferritinaemia cataract syndrome, an autosomal dominant hereditary disease, have been described. Patients with congenital bilateral nuclear cataract present high serum ferritin (360-2264 micrograms/l) in the absence of iron overload. The purpose of our study was to look for this syndrome in Switzerland and in particular in the Geneva population. About 3000 cases of cataract operated on during a 4-year period (1995-1998) in the University Clinic of Ophthalmology were screened. We found 135 patients operated on before the age of 51 years. However, only 19 had bilateral nuclear cataract. 15 patients agreed to undergo iron screening. In 2 of them, a slight elevation of ferritin (267 micrograms/l in a female, 416 micrograms/l in a male) was found in the absence of iron overload. In both cases there is a positive family history of cataract. DNA sequencing analysis in these patients showed a normal nucleotide sequence of the whole iron-responding elements region. One of them (male) was found to present the codon 63 mutation at HFE gene in the heterozygous state. Our local study indicates that hereditary hyperferritinaemia cataract syndrome is extremely rare in Switzerland. However, similar studies should be carried out in other regions of the country. Iron status evaluation and ferritin level monitoring should become routine examinations in all new cases presenting with bilateral nuclear cataract before the age of 50 years.