Guillermo Visedo

Proposed association between the COL1A1 and COL1A2 genes and otosclerosis is not supported by a case-control study in Spain

Otosclerosis (OTSC) is one of the most common causes of hearing loss in white adults. The COL1A1 and COL1A2 genes coding for type‐I collagen have been proposed as candidate genes in the development of OTSC. The COL1A1 gene was recently reported to be associated with the condition on the basis of a population‐based case‐control study. We report here an independent study of association between COL1A1 and COL1A2 gene polymorphisms and OTSC, in a case‐control sample from a population of Caucasian individuals living in Northwest Spain. Specifically, we studied two COL1A1 polymorphisms previously reported to be associated with OTSC, and six COL1A2 polymorphisms. We performed diverse association analyses based on alleles, genotypes, and two‐locus haplotypes. We found no evidence supporting the putative link of COL1A1 and COL1A2 genes with OTSC.

Detection of errors in dinucleotide repeat typing by nondenaturing electrophoresis.

This study shows that consideration of minor bands (heteroduplex, shadow, and faint bands) associated with allele bands in nondenaturing polyacrylamide gel electrophoresis (PAGE) after polymerase chain reaction (PCR) is effective for detecting PCR processing errors that lead to mistyping of heterozygotes as homozygotes. Notably, we show that minor bands in native gels are highly effective for detecting allele dropout and preferential amplification in PCR amplification of dinucleotide repeats. These findings are based on an analysis of Mendelian inheritance patterns in families, and the reproduction of heterozygous band patterns by mixing homozygous DNAs before PCR, for a total of six (AC)n repeats located on human chromosome 11p15. To investigate the utility of our approach, a large population sample of 405 unrelated individuals was genotyped for each (AC)n repeat using minor bands as internal quality controls. Genotype frequencies at each of the six loci were in close agreement with Hardy‐Weinberg proportions, which suggests that there were few genotyping errors. Our observations add to the evidence indicating that minor bands in native gels are of diagnostic value in the genotyping of dinucleotide repeats.

Genetic Polymorphism of Alpha-2-HS-Glycoprotein in a Spanish Population

The genetic polymorphism of alpha-2-HS-glycoprotein (AHSG) was analyzed in 489 unrelated individuals living in Madrid (central Spain), by isoelectric focusing in miniaturized polyacrylamide gels followed by immunoblotting. The allele frequencies were estimated to be 0.7147 and 0.2771 for AHSG*1 and AHSG*2, respectively. In addition to the common alleles, 3 rare variants (AHSG*3, AHSG*10 and AHSG*11) have been found in this study.

Isoelectric Focusing in Miniaturized Gels: Application to GC, PI, Tf and ORM Subtyping in Central Spain

Since the introduction of isoelectric focusing (IEF) for the analysis of protein polymorphisms of forensic science interest, several technical modifications have been developed to improve its reproducibility and resolution capacity. These include: IEF in a mixture of “separators” and carrier ampholytes (separator-IEF; SIEF) (Caspers et al. 1977; Gill et al. 1984); IEF in immobilized pH gradients (IEF-IPG) (Bjellquist et al. 1982; Cleve et al. 1982) and IEF in IPG-CA supplemented gels (hybrid-IEF; HIEF) (Atland et al. 1985).

Two-Dimensional Isoelectric Focusing Analysis of Rare and Silent Esterase D Types. Description of a New ESD Variant Phenotype

We have recently shown that the analysis of ESD phenotypes by onedimensional isoelectric focusing (1-D IEF) under reducing and mild denaturing conditions offers high resolution in the separation of the different ESD allele products (Alonso et al. 1991).Furthermore a new two-dimensional isoelectric focusing method (2-D IEF) has been described that permitted the identification of the ESD subunits from the homodimeric and heterodimeric forms of five common ESD phenotypes.