Alteration in sperm DNA could lead to infertility

 

Infertility is defined as the inability to achieve pregnancy after one year of unprotected intercourse.  But new guidelines to be published by a consortium of fertility groups advise women and men over 35 years of age to seek fertility evaluation if they fail to conceive only six months of trying.

At the recently concluded meeting fertility of the Asian Pacific Initiative on Reproduction in Malaysia in March 2017, additional focus was placed on male infertility. 

An estimated 15 per cent of couples are considered infertile, with approximately 35 per cent due to female factors alone, 30 per cent due to male factors alone, 20 per cent due to a combination of female and male factors and 15 per cent unexplained

Male infertility is usually caused by problems that affect either sperm production in the testes or sperm transport. The male gamete contributes 50 per cent of the genomic material to the embryo and contributes as well as to placental and embryonic development.

Genetic and epigenetic alterations of the sperm may, therefore, have important consequences on early pregnancy. Epigenetic alterations in the sperm, such as altered chromatin packing, imprinting errors, absence or alteration of the centrosome, telomeric shortening, and absence of sperm RNA, can affect some of the functional characteristics leading to early embryo loss. It is now noted worthy to realise that men may have a role to play when their partner has recurrent pregnancy loss.

Recurrent pregnancy loss is defined as the miscarriage of two or more consecutive pregnancies in the first or early second trimester of gestation. Although it may be associated with endocrine, anatomical, psychological, infectious, thrombotic, genetic, or immunological causes, more than 50 per cent of cases remain unexplained, even after an extensive diagnosis.

The frequency with which sperm defects contribute to recurrent pregnancy loss has not been established and the relationship between standard semen parameters and recurrent miscarriage has been a controversial subject. Partners of recurrent pregnancy loss patients show a significant increase in sperm chromosome aneuploidy, abnormal chromatin condensation, DNA fragmentation, increased apoptosis and abnormal sperm morphology compared with fertile men.

The initial step in the evaluation of an infertile male is to obtain a thorough medical and urologic history. Important considerations include the duration of infertility, previous fertility in the patient and the partner and prior evaluations. The couple should be asked specifically about their sexual habits, including their level of knowledge of the optimal timing of intercourse and the use of potentially spermatocytes and lubricants.

Patients should be asked about a history of childhood illnesses such as testicular torsion, post-pubertal mumps, developmental delay and precocious puberty, as well as urinary tract infections, sexually transmitted diseases, and bladder neck surgery. A history of neurological diseases, diabetes, and pulmonary infections should be elicited. Anosmia (lack of smell), galactorrhoea, visual-field defects, and sudden loss of libido could be signs of a pituitary tumour. The status of the partner’s workup should also be known.

The production of sperm is a complex process and requires normal functioning of the testicles (testes), as well as the hypothalamus and pituitary glands — organs in your brain that produce hormones that trigger sperm production. Once the sperm is produced in the testicles, delicate tubes transport them until they mix with semen and are ejaculated out of the penis. Problems with any of these systems can affect sperm production.

Low sperm count (oligospermia) is a leading cause of infertility or sub-fertility issues among men. While it requires only one sperm to fertilise the ovum, the odds of conception are such that it takes millions of sperm per milliliter of semen to actually achieve the goal of fertilisation. A “normal” sperm count is about 20 million or more sperm per millilitre of semen. Over sixty per cent of the sperm in each sample should exhibit normal morphology and indicate typical motility — the forward swimming movement.

Oligospermia is indicated in simple tests that reveal the concentration of sperm in a given sample quantity. Sperm count can, of course, be impacted by diet, frequency of intercourse, habits like smoking and drinking, and general health and wellness issues.

Anabolic steroids taken to stimulate muscle strength and growth can cause the testicles to shrink and sperm production to decrease. Use of cocaine or marijuana might reduce the number and quality of your sperm as well.

Drinking alcohol can lower testosterone levels and cause decreased sperm production.

Occupation. Certain occupations might be linked with a risk of infertility, including welding or those associated with prolonged sitting, such as truck driving. However, the data to support these associations is inconsistent.