A study of GluK1 kainate receptor polymorphisms in Down syndrome reveals allelic non-disjunction at 1173(C/T)

作者：Ghosh Debarati; Sinha Swagata; Chatterjee Anindita; Nandagopal Krishnadas^*

来源：Disease Markers, 2009, 27(2): 45-54.

DOI：10.3233/DMA-2009-0647

• Down syndrome
• mental retardation
• glutamate
• GluK1/GluR5/GRIK1
• allelic non-disjunction
• parent and stage of origin
• risk

Mechanisms underlying Down syndrome (DS)-related mental retardation (MR) remain poorly understood. In trisomic offspring, non-disjunction may result in the reduction to homozygosity of a susceptibility allele inherited from a heterozygous parent. Accordingly, we sought evidence for allelic non-disjunction in the GluK1 gene that encodes the critical kainite-binding glutamate receptor subunit-5, maps to chromosome 21q22.1 in the DS critical region and is expressed in brain regions responsible for learning and memory. Three polymorphisms of GluK1 [522(A/C) rs363538; 1173(C/T) rs363430 and 2705(T/C) rs363504] were genotyped in 86 DS patient families by means of PCR-coupled RFLP assays and evaluated with respect to allele frequency, heterozygosity, linkage disequilibrium, stage and parental origin of allelic non-disjunction. We report that the distribution of allele frequencies is in Hardy-Weinberg equilibrium. Moderate heterozygosity (0.339) and a major allele frequency of 0.78 render the 1173(C/T) marker informative. Pair-wise comparisons reveal that 522(A/C)-1173(C/T) [chi(2) = 31.2, df = 1, p = 0.0001; D' = 0.42] and 1173(C/T)-2705(T/C) [chi(2) = 18.3, df = 1, p = 0.0001; D' = 0.34] are in significant linkage disequilibrium of weak magnitude. The estimated ratio of meiosis-I to meiosis-II errors arising from allelic non-disjunction of 1173(C/T) is 4: 1 in maternal cases and 2: 1 in paternal cases. Studies including additional markers and patient samples are warranted to further substantiate present findings.

• 出版日期2009