Molecular characterization of a Y-derived marker chromosome and identification of indels in the DYS1 region in a patient with stigmata of Turner syndrome

Presence of the Y chromosome in human female and its absence in the male is an abnormal condition, implying a spectrum of genetic abnormalities. In this communication, we describe studies conducted on a 17-year-old patient (HK-459) with stigmata of Turner syndrome. We analysed the hormonal profile of the subject, chromosomal constitution and DNA for the five different loci encompassing both the arms of the Y chromosome. Chromosomal analysis showed mosaicism containing 45,X/46,X,+mar but no Y chromosome. The X chromosome and all the autosomes of the patient and her parents were normal. The Southern analysis of the patient's genomic DNA with probes specific to DYZ1 locus did not detect the corresponding Y-specific signal. Similarly, primers RG4, RG7 and PABY, corresponding to SRY gene and pseudoautosomal boundary regions respectively, failed to generate Y-specific amplicons. However, primers DYZ3 and DYS1, representing centromeric heterochromatic and euchromatic regions respectively, on the long arm of the Y chromosome uncovered Y-specific signals in the patient and her mother. Sequence analysis of DYS1-specific (710 bp) amplicon from the patient, both of her parents and two normal males showed insertion/deletion mutation in the patient. It is inferred that the Y-derived marker chromosome in the patient is of maternal origin and had undergone post-zygotic mutational events. The possible prognostic implications of this combined approach in the patient(s) with stigmata of Turner syndrome are discussed here

A Bidirectional Mendelian Randomization Study to evaluate the causal role of reduced blood vitamin D levels with type 2 diabetes risk in South Asians and Europeans.

Context Multiple observational studies have reported an inverse relationship between 25-hydroxyvitamin D concentrations (25(OH)D) and type 2 diabetes (T2D). However, the results of short- and long-term interventional trials concerning the relationship between 25(OH)D and T2D risk have been inconsistent. Objectives and methods To evaluate the causal role of reduced blood 25(OH)D in T2D, here we have performed a bidirectional Mendelian randomization study using 59,890 individuals (5,862 T2D cases and 54,028 controls) from European and Asian Indian ancestries. We used six known SNPs, including three T2D SNPs and three vitamin D pathway SNPs, as a genetic instrument to evaluate the causality and direction of the association between T2D and circulating 25(OH)D concentration. Results Results of the combined meta-analysis of eight participating studies showed that a composite score of three T2D SNPs would significantly increase T2D risk by an odds ratio (OR) of 1.24, p = 1.82 × 10–32; Z score 11.86, which, however, had no significant association with 25(OH)D status (Beta -0.02nmol/L ± SE 0.01nmol/L; p = 0.83; Z score -0.21). Likewise, the genetically instrumented composite score of 25(OH)D lowering alleles significantly decreased 25(OH)D concentrations (-2.1nmol/L ± SE 0.1nmol/L, p = 7.92 × 10–78; Z score -18.68) but was not associated with increased risk for T2D (OR 1.00, p = 0.12; Z score 1.54). However, using 25(OH)D synthesis SNP (DHCR7; rs12785878) as an individual genetic instrument, a per allele reduction of 25(OH)D concentration (-4.2nmol/L ± SE 0.3nmol/L) was predicted to increase T2D risk by 5%, p = 0.004; Z score 2.84. This effect, however, was not seen in other 25(OH)D SNPs (GC rs2282679, CYP2R1 rs12794714) when used as an individual instrument. Conclusion Our new data on this bidirectional Mendelian randomization study suggests that genetically instrumented T2D risk does not cause changes in 25(OH)D levels. However, genetically regulated 25(OH)D deficiency due to vitamin D synthesis gene (DHCR7) may influence the risk of T2D

Genome-Wide Linkage Scan to Identify Loci Associated with Type 2 Diabetes and Blood Lipid Phenotypes in the Sikh Diabetes Study

In this investigation, we have carried out an autosomal genome-wide linkage analysis to map genes associated with type 2 diabetes (T2D) and five quantitative traits of blood lipids including total cholesterol, high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol, very low-density lipoprotein (VLDL) cholesterol, and triglycerides in a unique family-based cohort from the Sikh Diabetes Study (SDS). A total of 870 individuals (526 male/344 female) from 321 families were successfully genotyped using 398 polymorphic microsatellite markers with an average spacing of 9.26 cM on the autosomes. Results of non-parametric multipoint linkage analysis using Sall statistics (implemented in Merlin) did not reveal any chromosomal region to be significantly associated with T2D in this Sikh cohort. However, linkage analysis for lipid traits using QTL-ALL analysis revealed promising linkage signals with p≤0.005 for total cholesterol, LDL cholesterol, and HDL cholesterol at chromosomes 5p15, 9q21, 10p11, 10q21, and 22q13. The most significant signal (p = 0.0011) occurred at 10q21.2 for HDL cholesterol. We also observed linkage signals for total cholesterol at 22q13.32 (p = 0.0016) and 5p15.33 (p = 0.0031) and for LDL cholesterol at 10p11.23 (p = 0.0045). Interestingly, some of linkage regions identified in this Sikh population coincide with plausible candidate genes reported in recent genome-wide association and meta-analysis studies for lipid traits. Our study provides the first evidence of linkage for loci associated with quantitative lipid traits at four chromosomal regions in this Asian Indian population from Punjab. More detailed examination of these regions with more informative genotyping, sequencing, and functional studies should lead to rapid detection of novel targets of therapeutic importance

Genome-wide association study identifies a novel locus contributing to type 2 diabetes susceptibility in Sikhs of Punjabi origin from India.

We performed a genome-wide association study (GWAS) and a multistage meta-analysis of type 2 diabetes (T2D) in Punjabi Sikhs from India. Our discovery GWAS in 1,616 individuals (842 case subjects) was followed by in silico replication of the top 513 independent single nucleotide polymorphisms (SNPs) (P < 10⁻³) in Punjabi Sikhs (n = 2,819; 801 case subjects). We further replicated 66 SNPs (P < 10⁻⁴) through genotyping in a Punjabi Sikh sample (n = 2,894; 1,711 case subjects). On combined meta-analysis in Sikh populations (n = 7,329; 3,354 case subjects), we identified a novel locus in association with T2D at 13q12 represented by a directly genotyped intronic SNP (rs9552911, P = 1.82 × 10⁻⁸) in the SGCG gene. Next, we undertook in silico replication (stage 2b) of the top 513 signals (P < 10⁻³) in 29,157 non-Sikh South Asians (10,971 case subjects) and de novo genotyping of up to 31 top signals (P < 10⁻⁴) in 10,817 South Asians (5,157 case subjects) (stage 3b). In combined South Asian meta-analysis, we observed six suggestive associations (P < 10⁻⁵ to < 10⁻⁷), including SNPs at HMG1L1/CTCFL, PLXNA4, SCAP, and chr5p11. Further evaluation of 31 top SNPs in 33,707 East Asians (16,746 case subjects) (stage 3c) and 47,117 Europeans (8,130 case subjects) (stage 3d), and joint meta-analysis of 128,127 individuals (44,358 case subjects) from 27 multiethnic studies, did not reveal any additional loci nor was there any evidence of replication for the new variant. Our findings provide new evidence on the presence of a population-specific signal in relation to T2D, which may provide additional insights into T2D pathogenesis

Karyotypic findings in chronic myeloid leukemia cases undergoing treatment

Background: Chronic myeloid leukemia (CML) is a clonal myeloproliferative expansion of primitive hematopoietic progenitor cells. Materials and Methods: In the present study, CML samples were collected from various hospitals in Amritsar, Jalandhar and Ludhiana. Results: Chromosomal alterations seen in peripheral blood lymphocytes of these treated and untreated cases of CML were satellite associations, double minutes, random loss, gain of C group chromosomes and presence of marker chromosome. No aberrations were observed in control samples. Karyotypic abnormalities have also been noted in the Ph-negative cells of some patients in disease remission. Conclusion: This is a novel phenomenon whose prognostic implications require thorough and systematic evaluation

Karyotypic findings in chronic myeloid leukemia cases undergoing treatment

Background: Chronic myeloid leukemia (CML) is a clonal myeloproliferative expansion of primitive hematopoietic progenitor cells. Materials and Methods: In the present study, CML samples were collected from various hospitals in Amritsar, Jalandhar and Ludhiana. Results: Chromosomal alterations seen in peripheral blood lymphocytes of these treated and untreated cases of CML were satellite associations, double minutes, random loss, gain of C group chromosomes and presence of marker chromosome. No aberrations were observed in control samples. Karyotypic abnormalities have also been noted in the Ph-negative cells of some patients in disease remission. Conclusion: This is a novel phenomenon whose prognostic implications require thorough and systematic evaluation