Great paper by @DMalawsky, @hilsomartin and the team on the associations of consanguineous union with common diseases. Consanguinity (i.e., marrying close relatives e.g. cousin marriages) results in the passing of very similar genomes from father and mother to the offspring. This increases the load of recessive deleterious mutations in the offspring, which can be inferred from genetic data by quantifying the stretches of homozygous genotypes (described as autozygosity). Consanguineous marriages are highly common in many South-Asian populations. The negative health consequences of consanguineous unions are well known in the context of rare recessive severe diseases such as skeletal deformities, intellectual disability etc. However, the effect of consanguineous unions on the risk of common diseases is not well studied. This is very important as diseases like type-2 diabetes are highly common in South-Asian populations. Here by analyzing genetic and phenotypic data of two South-Asian cohorts, the authors show that consanguinity strongly increases the risks of even common diseases. For example, in communities practising consanguineous marriages, more than 10% of type 2 diabetes might be due to autozygosity (and this is probably an underestimate). What type of genetic variants are mediating the association between autozygosity and increased risk of common diseases? Likely rare recessive variants acting in a non-additive manner. To pinpoint which recessive variants are driving which diseases, we will need extremely large sample sizes as homozygous genotypes are extremely rare (square of minor allele frequency). An important research contribution to the South-Asian communities by Malawsky et al. 👏👏