First genetic risk factor for erectile dysfunction identified.
Erectile dysfunction (ED), also known as impotence, is the inability to get and maintain an erect penis. ED is a very common condition, particularly in older men where it is estimated that half of all men between the ages of 40 and 70 suffer from ED to some degree. ED is linked to many causes, such as psychological, hormonal and vascular factors. Genetic factors are also suspected in about one-third of erectile dysfunction cases, however, it has proved difficult for researchers to identify any specific genomic locations. Now, a study from researchers led by Kaiser Permanente isolates a specific place in the human genome where variations can raise a person’s risk of erectile dysfunction. The team state their study highlights the potential of SIM1 as a target for the development of new treatments for ED, which are needed as around 50% of men who try currently available pharmaceutical treatments for ED don’t respond to them. The opensource study is published in the journal PNAS.
Previous studies show ED is a common condition of men in middle and older ages, and tied to psychosocial, neurological, hormonal, and vascular factors. A twin study in middle-aged male veterans found that about one-third of the risk is heritable due to genetic factors, independent of other known erectile dysfunction risk factors. However, studies which have searched for specific genetic contributors have been limited due to small sample sizes, candidate gene approaches, and weak phenotyping. As a result, there are no confirmed genetic risk factors for ED. The current study identifies variations in a specific place in the genome, near the SIM1 gene, which are significantly associated with an increased risk of ED.
The current study investigates medical records and DNA samples from 36,649 men in the Kaiser Permanente GERA cohort to identify a genomic region, or locus, associated with ED risk. The group also validated these results in a second study cohort, based on records and DNA from 222,358 men in the U.K. Biobank. Results show that variations in the locus near the SIM1 gene are significantly associated with an increased risk of erectile dysfunction, with all other known risk factors for ED ruled out. Data findings show that variations in the SIM1 locus are associated with a 26% increased risk of ED.
The lab explain the SIM1 gene is known to be part of a signalling pathway which plays a central role in body weight regulation and sexual function; the ED locus is located near, not in, the SIM1 gene. They go on to add they show the risk location physically interacts with the promoter of the SIM1 gene, and that variants in this location alter the function of a master gene regulator, called an enhancer; and because the ED risk locus showed enhancer activity and interacted with the SIM1 promoter, the ED risk locus likely influences the expression of the SIM1 gene, turning it on and off when needed.
The team surmise they have identified a specific genetic cause for ED. For the future, the researchers state their study could help identify other key genetic variants which trigger ED.
Source: Kaiser Permanente