Medical and population genomics
We analyse large-scale genetic and electronic health record data to explore fine-scale population structure, its impact on disease risk, and the genetic architecture of both rare and complex diseases. We have a particular focus on populations in which parental relatedness (consanguinity) is common. Our current projects use data from the following studies:
- East London Genes and Health (ELGH) is a population-based cohort of British South Asians with high rates of cardiometabolic disease and of parental relatedness (current N~35,000, and growing to 100,000). Electronic health record and genotype data are available on all individuals, and exome-sequence data on ~5,000.
- Born in Bradford (BiB) is a birth cohort with data on ~11,000 mothers and their children, of whom about half have Pakistani ancestry. It was established to investigate determinants of child and adult disease, and includes rich phenotypic and environmental data as well as genetic (genotype and whole-exome) and metabolomic data.
- Deciphering Developmental Disorders (DDD) is a study of >13,000 patients with rare, severe paediatric disorders who have been exome-sequenced and genotyped to find diagnoses, discover new genes and understand the genetic architecture of these conditions.
- Genomics England - 100K Genomes Project (GEL) is a clinical whole-genome sequencing project embedded within the National Health Service, from which the data have been made available for research. We are particularly focusing on the ~20,000 families with rare paediatric disease, of whom ~10% are South Asian.
A key feature of our research is to work in partnership with the individuals and populations we are studying. We uphold strict data security and confidentiality procedures and work closely with cohorts we are studying in community engagement and dissemination of our scientific findings.
Population structure and history in British South Asians
South Asia has an immensely complex population history, with thousands of anthropologically different groups, many of them characterised by hundreds or even thousands of years of endogamy. They also represent one of the largest immigrant groups in the UK. We are currently characterising the population structure and history of British Pakistanis and Bangladeshis using data from the Born in Bradford and East London Genes and Health projects. Specifically, we are using genotype-chip data and self-reported information on ethnic, tribal and biraderi (patrilineal kinship) groups to explore genetic differences and similarities between these groups as well as historical population size changes. We are then comparing this with historical and ethnographic accounts of group dynamics. Furthermore, we are exploring the extent to which historical bottlenecks have produced founder effects on Mendelian disease-causing variants.
The genetic basis of complex disease in South Asian populations
Most studies of the genetics of complex disease have taken place in European ancestry populations, and it is well established that the results do not necessarily translate well into other populations. British South Asians have particularly high rates of type 2 diabetes and ischaemic heart disease, but our understanding of the genetic contribution to these conditions in this population is lagging behind that for European-ancestry individuals. We are exploring the portability of polygenic scores for various traits from Europeans into South Asians, and the best methods for doing this to maximise prediction accuracy. We will analyse genotype and electronic health record data from ELGH to discover new associations and to aid trans-ethnic fine-mapping, and use this to improve genetic prediction in South Asians. Additionally we are exploring the contribution of autozygosity due to recent consanguinity to various complex traits, and investigating mechanisms driving this.
Parental relatedness (consanguinity) is common in some South Asian communities, and increases the probability of an individual inheriting two copies of the same rare variant. Hence, consanguineous individuals are highly enriched for rare homozygous loss-of-function variants (knockouts), which can be informative about gene function and new drug targets. We are investigating the effects of knockouts in the BiB and ELGH projects through association analysis with various phenotypes including metabolite levels, and through recall-by-genotype studies.
Genetic architecture of rare neurodevelopmental disorders
Rare and de novo large-effect exonic variants are known to play a major role in rare neurodevelopmental disorders (NDDs) such as intellectual disability and epilepsy. However, it is becoming increasingly clear that polygenic background plays a role. We are investigating how common variants impact the penetrance and expressivity of rare variants, particularly in the context of NDDs and cognition, examining both polygenic background and the role of eQTLs modifying penetrance in cis. We are also exploring whether there is a role for autozygosity in NDDs beyond the mechanism of simple monogenic recessive inheritance.
Human Genetics Administration
The Human Genetics Administration comprises a five strong team that provides comprehensive support for the smooth running of the Human Genetics ...
Human Genetics Informatics (HGI)
Human Genetics Informatics (HGI) supports the scientific aims of the Human Genetics programme by developing and operating computational analysis workflows, managing ...
The Martin Group collaborates with the following groups at the Sanger Institute:
East London Genes & Health is one of the world’s largest community-based genetics studies, aiming to improve health among people of Pakistani and Bangladeshi heritage in East London by analysing the genes and health of 100,000 local people.