Some of our researchers believe that consanguinity is one of the causative agent of human infertility. Is it possible or not? If the consanguinity is the causative agent, then what is the reason behind that? What kind of changes take place due to consanguinity?
Yes it is possible. In fact, the main impact of consanguinity is an increase in the rate of homozygotes for autosomal recessive genetic disorders including (at least) some particular and rare genetic forms of male infertility.
If you put the two terms "consanguinity" and "infertility" into PubMed you get a lot of results (including the role of consanguinity in the ending of the Hapsburg dynasty of Kings). This paper seems relevant however: "Consanguinity and family clustering of male factor infertility in Lebanon." http://www.ncbi.nlm.nih.gov/pubmed/18367181
I'm afraid I can only access the abstract as it is behind a pay wall but the conclusion states: "This study demonstrated a significant association between consanguinity and family clustering of male factor infertility cases, suggesting a strong genetic component".
In the UK there used to be a term "kissing cousins". These were the cousins you were allowed to marry (2nd cousins or even less related cousins- 1st cousins you were not)
A hot gene that could be causing this is CFTR. Some of the CFTR mutations are associated with congenital absence of the vas deferens. Since about 50% of vas deferens minus guys have CFTR mutations it would appear that this is a major cause of male infertility. CFTR mutations are relatively common anyway. So, I think that consaguinous marriages would explain some infertility directly through recessive CFTR mutations expressing through affected males. http://ghr.nlm.nih.gov/condition/congenital-bilateral-absence-of-the-vas-deferens
Yes, relatives are more likely to share similar mutations (sometimes due to a founder effect). Many inactivating mutations within reproductive genes need to be expressed in the homozygous state or be compound inactivating mutations (two different mutations in the same gene but each are non-functional) to get a reproductive phenotype (e.g. infertility). If relatives who possess similar heterozygous inactivating-mutations (in a reproductive gene) were to have children, these children would have a higher rate of possessing the same mutation in a homozygous state causing a reproductive deficiency. Some examples are hypogonadotropic hypogonadism and its associated infertility due to gene mutations in Kiss1, the Kiss1 receptor, GnRH receptor, neurokinin B, neurokinin B receptor, to name a few. However these mutations are relatively rare.
thanks to all of you.
Will some one will provide me the articles related to the cousin marriages and infertility
yes there are chances of Homozygous autosomal recessive disorders in couples of consanguious marriages.the mutations depend on the degree of relations.its more common in the second degree relatives.these genetic combinations may lead to infertility, Autosomal disorders,congenital malformations.we see this in our practice also.
How many genes are responsible for the infertility? Can any one provide an articles about this problem?
Respected Gary Morley
can you provide the full paper
http://www.ncbi.nlm.nih.gov/pubmed/18367181
Hello,
This is a nice debate, your question "consanguinity causing human infertility"?. Several researchers have provided their reports worldwide. But it is still unclear/ or misconception. Some people relate "child mortality " with infertility", which is big a misconception. The homozygosity of autosomal genes may eliminate the new born baby, which is unfit genetically. If you go through many recent reports, shows fertility not affected by inbreeding, but Net fertility may decreases, which has been calculated from mortality.
I am studying the same problem, I have found the degree of inbreeding or consanguinity leads to increase of gross fertility but mortality also persuasively increased. Inbreeding in new or recent populations may affects adversely, but in old populations who practicing it for hundreds of years and thousands of years, the harmful genes either eliminate or/ selection fix the such problems.
However, there are many other traits, and disorders like physical, cognitive, behavioral, complex diseases etc. much influenced by the level of inbreeding.
Please take a look at this useful link.
https://www.rbmojournal.com/article/S1472-6483(15)00262-X/pdf
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