Biology subjects

Gareth Highnam

Publications and source records attributed to Gareth Highnam.

4 recordsLinked to original sources

bioRxiv2015

Whole genome analysis of an extended pedigree with Prader–Willi Syndrome, hereditary hemochromatosis, and dysautonomia-like symptoms

This report includes the discovery and analysis of a pedigree with Prader-Willi Syndrome (PWS), hereditary hemochromatosis (HH), and dysautonomia-like symptoms. Nine members of the family participated in whole genome sequencing (WGS), which enabled a wide scope of variant calling from single-nucleotide polymorphisms to copy number variations. First, a 5.5 Mb de novo deletion is identified in the chromosome region 15q11.2 to 15q13.1 in the boy with PWS. Second, a female invididual with HH is homozygous for the p.C282Y variant in HFE, a mutation known to be associated with HH. Her brother is homozygous for the same variant, although he has yet to be clinically diagnosed with HH. Third, none of the people with dysautonomia-like symptoms carry any reported or novel rare variants in IKBKAP that are implicated in familial dysautonomia (FD - HSAN III). Although two people with dysautonomia-like symptoms carry two heterozygous variants in NTRK1, a gene that has been shown to contribute to HSAN IV (congenital insensitivity to pain with anhidrosis, a disease that closely resembles FD), this variant is not present in the third proband. Fourth, WGS revealed pharmacogenetic variants influencing the metabolism of warfarin and simvastatin, which are being routinely prescribed to the proband. Finally, reports of the phenotypes were standardized with the Human Phenotype Ontology annotation, which may facilitate the search for other families with similar phenotypes. Due to the extreme heterogeneity and insufficient knowledge of human diseases, it is of crucial importance that both phenotypic data and genomic data are standardized and shared.

Genetics↗

bioRxiv2015

Tandem repeat variation in human and great ape populations and its impact on gene expression divergence

Tandem repeats (TR) are stretches of DNA that are highly variable in length and mutate rapidly, and thus an important source of genetic variation. This variation is highly informative for population and conservation genetics, and has also been associated with several pathological conditions and with gene expression regulation. However, genome-wide surveys of TR variation have been scarce due to the technical difficulties derived from short-read technology.\n\nHere, we explored the genome-wide diversity of TRs in a panel of 83 human and nonhuman great ape genomes, and their impact on gene expression evolution. We found that populations and species diversity patterns can be efficiently captured with short TRs (repeat unit length 1-5 base pairs) with potential applications in conservation genetics. We also examined the potential evolutionary role of TRs in gene expression differences between humans and primates by using 30,275 larger TRs (repeat unit length 2-50 base pairs). About one third of the 13,035 one-to-one orthologous genes contained TRs within 5 kilobase pairs of their transcription start site, and had higher expression divergence than genes without such TRs. The same observation held for genes with repeats in their 3 untranslated region, in introns, and in exons. Using our polymorphism data for the shortest TRs, we found that genes with polymorphic repeats in their promoters showed higher expression divergence in humans and chimpanzees compared to genes with fixed or no TRs in the promoters. Our findings highlight the potential contribution of TRs to recent human evolution through gene regulation.

Evolutionary Biology↗

bioRxiv2015

A variant in TAF1 is associated with a new syndrome with severe intellectual disability and characteristic dysmorphic features

We describe the discovery of a new genetic syndrome, RykDax syndrome, driven by a whole genome sequencing (WGS) study of one family from Utah with two affected male brothers, presenting with severe intellectual disability (ID), a characteristic intergluteal crease, and very distinctive facial features including a broad, upturned nose, sagging cheeks, downward sloping palpebral fissures, prominent periorbital ridges, deep-set eyes, relative hypertelorism, thin upper lip, a high-arched palate, prominent ears with thickened helices, and a pointed chin. This Caucasian family was recruited from Utah, USA. Illumina-based WGS was performed on 10 members of this family, with additional Complete Genomics-based WGS performed on the nuclear portion of the family (mother, father and the two affected males). Using WGS datasets from 10 members of this family, we can increase the reliability of the biological inferences with an integrative bioinformatic pipeline. In combination with insights from clinical evaluations and medical diagnostic analyses, these DNA sequencing data were used in the study of three plausible genetic disease models that might uncover genetic contribution to the syndrome. We found a 2 to 5-fold difference in the number of variants detected as being relevant for various disease models when using different sets of sequencing data and analysis pipelines. We de-rived greater accuracy when more pipelines were used in conjunction with data encompassing a larger portion of the family, with the number of putative de-novo mutations being reduced by 80%, due to false negative calls in the parents. The boys carry a maternally inherited mis-sense variant in a X-chromosomal gene TAF1, which we consider as disease relevant. TAF1 is the largest subunit of the general transcription factor IID (TFIID) multi-protein complex, and our results implicate mutations in TAF1 as playing a critical role in the development of this new intellectual disability syndrome.

Genetics↗

bioRxiv2014

The Landscape of Human STR Variation

Short Tandem Repeats are among the most polymorphic loci in the human genome. These loci play a role in the etiology of a range of genetic diseases and have been frequently utilized in forensics, population genetics, and genetic genealogy. Despite this plethora of applications, little is known about the variation of most STRs in the human population. Here, we report the largest-scale analysis of human STR variation to date. We collected information for nearly 700,000 STR loci across over 1,000 individuals in phase 1 of the 1000 Genomes Project. This process nearly saturated common STR variations. After employing a series of quality controls, we utilize this call set to analyze determinants of STR variation, assess the human reference genomes representation of STR alleles, find STR loci with common loss-of-function alleles, and obtain initial estimates of the linkage disequilibrium between STRs and common SNPs. Overall, these analyses further elucidate the scale of genetic variation beyond classical point mutations. The resource is publicly available at http://strcat.teamerlich.org/ both in raw format and via a graphical interface.

Genomics↗