At A Level, we are taught that dominant: recessive traits are in a 3:1 ratio for any trait in which only one gene encodes for it. However, it’s not always that simple. Enter lethal alleles…
Sources for this episode: 1) Author unknown, Wikipedia (date unknown), Lethal allele (online) [Accessed 26/03/2021]. 2) Author unknown, Wikipedia (date unknown), Manx cat (online) [Accessed 27/03/2021]. 3) Gao, Z., Waggoner, D., Stephens, M., Ober, C. and Przeworski, M. (2015), An Estimate of the Average Number of Recessive Lethal Mutations Carried by Humans. Genetics 199: 1243- 1254. 4) Roos, R. A. C. (2010), Huntingdon’s disease: a clinical review. Orphanet Journal of Rare Diseases 2010 5:40. 5) For an example of the deleterious effects of inbreeding as discussed in today’s episode, see the Wikipedia or Encyclopaedia Britannica pages on Charles II of Spain. I might come back to him and his ailments in a separate episode, but until then he will also serve as a good example.