Resumen de Potential for natural selection at the Machado Joseph Disease Locus: A comparative study of the Azores Islands and Mainland Portugal
M. Lima, C. Silva, C. Santos, A. Abade
Disease-causing genes are expected to be maintained at low frequencies in human populations.Among the several exceptions to this trend is Machado-Joseph disease (MJD), an hereditaryneurodegenerative disorder, associated with the expansion of a (CAG)ₙ tract in the causative gene. MJDreaches high values of prevalence in Portugal, namely in the Azores Islands. In this work we presentresults on the Genetic Fitness of 26 MJD patients from the Azores and 20 patients from MainlandPortugal. Reproductive outcome was studied for 46 couples where one member was an MJD patient.Analysis were performed taking the place of origin (Azores/Mainland) and the sex of the patient intoaccount. No significant differences were found in fertility or mortality when comparing the patientsfrom the Azores and from Mainland Portugal. However, when comparing the totality of patients bysex, differences were observed for the number of successful offspring, with women contributing a highernumber of children that survive and marry in the population. To understand the interaction betweenthe fertility and mortality components of Fitness, the Crow's Index of Opportunity for Selection wascalculated.
