Infertility is the inability for a couple to conceive a pregnancy while being sexually active without contraception for 12 or more months. Male infertility is due to low sperm count, abnormal sperm function, or blockages within the male reproductive tract and can be caused by hereditary, environmental, or biological factors (1,2).
Symptoms and Risk Factors Edit
The main sign of male infertility is the inability to conceive a child after a year of regular, unprotected sex. There may not be any other signs, however, others may be present due to other underlying problems. The symptoms may include pain or swelling in the testes, decreased sexual function (such as difficulty with ejaculation), decreased facial or body hair, and lower sperm count (2)
Some men may be at a higher risk for male infertility than others due to illnesses, chronic health problems, and lifestyles. Some factors that may increase the risk for male infertility are smoking, regular alcohol use, exposure to certain toxins, overheating of the testicles, being overweight, and using certain medications (2).
Male Infertility SNPs Edit
There are many SNPs associated with male infertility, however, the ones with the strongest correlation are rs955988, rs10842262, and rs10910078. In the European and Asian population, each copy of a C nucleotide at rs955988 increases the odds of male infertility 1.25 times and each copy of a T nucleotide at rs10910078 increases the odds 1.4 times. Those who study male infertility do not use standard SNP codes, therefore, it is difficult to assign infertility results to SNPs (4, 5).
Genetics and Male Infertility Edit
The association between genetic defects and male infertility are low, however, tests can be done if defects are suspected. Symptoms that suggest a genetic defect are low sperm count or no sperm in the semen, several miscarriages, or physical features, such as testicle size. The three tests that can be performed are chromosome analysis, Y chromosome microdeletion test, and the cystic fibrosis gene test. The chromosome test, also known as the karyotype, examines the number of chromosomes and shows if a person has extra copies or missing chromosomes. The Y chromosome microdeletion test determines if the Y chromosome is complete and has all the necessary genetic information for normal sperm production. Finally, the cystic fibrosis gene test detects mutations in the cystic fibrosis gene that can cause male infertility (3).
Genetic tests can discover many genetic causes for infertility. Chromosome analyses can detect Klinefelter syndrome, which occurs when a man inherits two X chromosomes, giving him XXY sex chromosomes. Klinefelter syndrome is a fairly common disorder occurring in 0.2% of males and results in a lower testosterone level and very little to no sperm in their semen. Chromosome analysis can also detect balanced translocations, which is a difference in chromosome set up. Balanced translocations can lead to miscarriages and infertilities, as well as birth defects in the children. Balanced translocations are very rare and are not often the cause of male infertility. Y chromosome microdeletion can detect if the areas coding for male fertility in the Y chromosome are missing. The specific portion of missing Y chromosome is essential to estimating the chances of having sperm in the testicle. The cystic fibrosis gene mutation test tests the gene seen in 0.03% of the Caucasian population. There are variant forms of the cystic fibrosis gene that can affect fertility only. This is important to rule out because the gene can cause other health issues and can be passed to the next generation (3).
Why is Knowledge About Male Infertility Important? Edit
Male infertility can be caused by a wide variety of factors, including tumors, hormone imbalances, celiac disease, autoimmune disorders (antibodies attacking own sperm), and chromosomal imbalances. Often discovering the cause of infertility can improve health as well as personal relationships. Infertility can take a toll on a couple, as not being able to conceive can be frustrating and stressful. Figuring out the core reason for infertility can help discover which treatment will yield the best results (2).
If the cause of infertility is due to genetic disorders, there is a chance for offspring to inherit the defects. Therefore, it is also important to know the cause so the risk of the children inheriting the genes can be discussed between the doctor and the couple (2).
John Burke's genotype at rs955988 is TT, which means he has the typical odds for low sperm count. Therefore, he has a generally healthy reproductive system (5). There is a great chance his fertility level is normal and it is unlikely his children will have fertility problems.
1. World Health Organization, Sexual and Reproductive Health.
2. Mayo Clinic, Male Infertility
3. Cleveland Clinic, Diseases and Conditions
4. SNPedia, Male Infertility
5. 23 and Me, John Burke Results