PubMed Health⌕ Search

Biomedical subjects

R Hamvas

Publications and source records attributed to R Hamvas.

7 recordsLinked to original sources
PubMed2002

An interaction between the IL-4Ralpha gene and infection is associated with atopic eczema in young children.

BACKGROUND: A gain of function mutation (Q551- > R) in the IL-4 receptor alpha-chain (IL-4Ralpha) has been found to be associated with atopy in some studies but not others. The different results may be explained by interactions between the IL-4Ralpha polymorphism and environmental factors. OBJECTIVES: To identify interactions between the R551 mutation and environmental factors that are associated with atopy. METHODS: DNA from the Children in Focus (CiF) cohort of the Avon Longitudinal Study of Parents and Children (ALSPAC) was genotyped by heteroduplex formation for the presence of the R551 polymorphism. The data were then analysed for associations with flexural eczema as an indicator of atopic eczema, skin prick tests to allergens and serum IgE levels, and for interactions with environmental factors. RESULTS: A significant (P = 0.02) positive association was seen between the R551 polymorphism and flexural eczema in children up to 6 months of age who had not been given antibiotics, but not in children who had been given antibiotics. This association was maintained as a trend until 30 to 42 months of age but was no longer statistically significant. There was no significant association between the R551 polymorphism and positive skin prick tests or levels of serum IgE at 61 months of age, consistent with the effect of the R551 polymorphism being restricted to early life. CONCLUSION: There is an association between the R551 polymorphism and flexural eczema in children at 6 months of age who have not had infection requiring treatment with antibiotics. Restriction of the R551 association with eczema to children who have not had antibiotics lends support to the 'hygiene hypothesis', which states that exposure to infection in childhood can protect against allergic disease.

Bacterial Infections↗
PubMed2000

A new human genetic resource: a DNA bank established as part of the Avon longitudinal study of pregnancy and childhood (ALSPAC).

We describe a unique human DNA resource forming part of the Avon Longitudinal Study of Pregnancy and Childhood (ALSPAC), a longitudinal cohort study involving 14 000 children and their families living in a geographically defined area of England. The DNA bank will underpin the search for associations between genetic polymorphisms and common health outcomes. The opportunities to collect blood samples suitable for DNA extraction are necessarily limited, and the samples themselves have often been treated in different ways and have varied storage histories. With the need to maximise yields, the choice of DNA extraction method is critical to the success of the bank and we have investigated the suitability of various commercial and in-house methods of DNA extraction. Various steps have been taken to minimise errors in sample address and identification, including the use of a pipetting robot for dilution and transfer of samples between 96-well arrays to provide aliquots suitable for PCR. The robot has been programmed to cope with concentrated viscous DNA solutions.

Animals↗
PubMed1996

Sub-milliMorgan map of the proximal part of mouse Chromosome 17 including the hybrid sterility 1 gene.

We have generated a high-resolution genetic map, 0.071 cM per backcross animal, of the 13 cM T-H2 region of the mouse Chromosome (Chr) 17. The map contains two phenotypic loci, T and Hst1, 12 RFLP markers, and 24 microsatellite loci. The Hst1 gene was mapped to a chromosomal interval contained within a single 580-kb YAC clone. The FFEH11 YAC is 0.44 cM long and carries, besides the Hst1 gene, five polymorphic DNA markers and recombination breakpoints of six backcross animals. Two candidate genes for Hst1 were identified based on their location and testicular expression. These are Tbp and D17Ph4e. The submilliMorgan map of the T-H2 region revealed significant clustering of (CA)n loci. The clustering, if shown to be a common feature in the mouse genome, may cause gaps in the physical map of the mouse genome.

Animals↗
PubMed1996

Xist expression from an Xist YAC transgene carried on the mouse Y chromosome.

We have constructed mouse transgenic lines carrying a YAC clone encompassing the Xist gene in order to investigate the factors influencing Xist expression and the initiation of X-inactivation. Two transgenic lines were derived, one carrying four copies integrated at an autosomal site and a second line carrying four copies integrated at a single site on the Y chromosome. Xist expression was not observed in mice carrying the autosomal insertion. However, Xist expression from the Y-inserted transgenes was observed and at levels commensurate with that found in normal female mice. Methylation sites in the autosomal transgene both 5' and 3' of the Xist gene are hypermethylated and appear to reflect methylation patterns observed on the active X chromosome. For the Y-linked transgene, methylation sites 5' and 3' of the Xist gene are hypomethylated reflecting patterns found on the inactive X chromosome. However, the 5' and 3' methylation levels have been decoupled at the active transgenic locus. The data suggest that sequences in the vicinity of Xist can initiate some of the features that are associated with the initiation process of X-inactivation.

Animals↗
PubMed1994

A 1.2-Mb YAC contig spans the quaking region.

We describe here a 1.2-Mb yeast artificial chromosome (YAC) contig within the region of mouse chromosome 17 between Brachyury (T) and D17Rp17e, and spanning the quaking (qk) region. We describe six new probes distributed across 1.2 Mb: D17Leh502, D17Leh503, D17Leh504, D17Leh505, D17Leh506, and D17Leh507. Probes D17Leh502 and D17Leh507 are at the extreme ends of the YAC contig. With the exception of D17Leh507, all of these probes are within a deletion associated with the quaking(viable) (qkv) allele of quaking. We have positioned these probes on a detailed YAC physical map together with two previously published probes, D17Leh508 and D17Aus119. We show here that D17Leh508 is also within the qkv deletion. Genetic mapping of D17Leh504 and D17Leh507 on two high-resolution genetic crosses carrying qkv and quaking(lethal-1) (qkl-1) alleles shows that these probes do not recombine with quaking and are therefore within 0.04 cM of qkv and 0.05 cM of qkl-1 mutations. The deletion breakpoint contained within the YAC contig has been positioned to within 90 kb by restriction mapping of wildtype and mutant DNA. This contig will form the basis for identification and mapping of expressed sequences and for an investigation of genome organization.

Alleles↗