Researchers regularly repeat GWAS as more samples and more SNP sites become avai

Question

Researchers regularly repeat GWAS as more samples and more SNP sites become available. For example, in 2017, a study was published that looked at human height in 700K subjects and identified 83 associated loci with large effect sizes. (a) Previous studies in 2008 and 2010 sampled 80K and 150K subjects, and revealed 80 and 250 associated loci. What scientific value was there in repeating this study with a much larger number of subjects? (b) GWAS studies have highlighted the problem of "missing" or "hidden" heritability. From twin studies, the heritability of human height is estimated to be 80%. This study describes the genetic basis for only a small fraction of this heritability (30%). Develop one or two hypotheses to account for where the missing heritability might be. (c) Sketch on plot showing what you would expect to see from a hypothetical genomic region of this GWAS study that contains 3 SNPs of P

Explanation / Answer

In field of genetics a genome wide association study also known as whole genome association study is a observational study of a genome wide set of genetic variants in different individuals to see if any variant is associated with a trait . GWAS typically focus on associations between single nucleotide polymorphism that is SNPs and a trait like major human disease but can equally be applied to any othe organism.

phenotypic first is a approacch in which the participants are classified first by their manifestation as opposed to genotype first . where each person gives a saple of dna from which millions of genetic variants are read using SNP arrays . If one type of variant is more frequent in people withthe disease the variant is associated with the disease . a manhattan plot is a type of scatter plot usually used to display data with a large no. of data points many of non zero amplitude and with the distribution of higher manitude.

In GWAS Manhattan plots , genomic coordinates are displayed along the X axis with the negative logarithm of association P- value for single single nucleotide polymorphism displayed on Y axis , meaning that the each dot on the manhattan plot signifies a SNP .

because the strongest associations have the smaller p values the negative logarithms will be greater.

Related Questions

Navigate

• Browse (All)
• Browse R
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.