I'm new in this field. I was reading Shakeel et al. (2018) and came across the below sentences
The rate of emergence and distribution of deleterious variants in populations is important in determining the patterns of underlying genetic load for diseases, because the increased accumulation of genetic load of diseases due to non-random segregation of deleterious variants is so detrimental that fixation or near fixation of these mutations can play a significant role in the extinction of isolate populations with small effective population size.
I'm not sure to correctly understand the concept of the sentences, especially
genetic load of disease and its accumulation due to non-random segregation of deleterious variants.
Could you please kindly explain a bit to me about it?
Many thanks in advance