In the past, the causes of infertility were unknown. This is due to the fact that symptoms are hardly ever detectable. Most infertile individuals do not experience any symptoms at all. The small percentage that does show symptoms is very likely to receive an incorrect diagnosis. This occurs because the symptoms are very common to other illnesses as well. Symptoms such as loss of strength, and fatigue are common to many different conditions (Nachtigall LB, et al., 1997).

This disease was believed to be predominant in females. This assumption is incorrect, since males show the highest percentage of infertility in comparison to females.

Due to the complexity of spermatogenesis, the process through which millions of sperm cells are produced, the probability of defective sperm is higher than that of an egg in the female reproductive cycle. For spermatogenesis to be successful it requires the presence of androgens, and a

Results suggested that the mean CAG repeat length increased with the severity of the spermatogenic defect in the 30 patients with idiopathic spermatogenic disorders. Men with infertility were more likely than were controls to have expanded CAG repeats in their androgen-receptor gene. Similar outcomes were obtained in similar studies with Asian and Indian men, indicating that the results are not related to any specific ethnic group. This mutation could be inherited possibly leading to an increase in male infertility in future generations. Should further elongation of the CAG repeat occur in these future generations, there is an added risk of increased severity of male infertility, potentially an increased incidence of neurodegenerative disease (Dowsing AT, et al., 1999).

functional androgen receptor. This androgen-modulated, DNA-binding protein regulates transcription of androgen target genes.

Analyses of trinucleotide (CAG) repeat length and point mutations in the androgen-receptor gene are done by PCR, single-stranded conformational polymorphism, and DNA sequencing. When 32 controls and 35 infertile men were screened for androgen- receptor gene mutations, the genomic DNA samples were coded, and were analyzed without knowledge of the clinical of the patients. The CAG repeat lengths of the androgen-receptor gene was assessed by means of a PCR with primers specific for the repeat segment. The trinucleotide repeat loci (CAG) were amplified by PCR, and the exact number of CAG repeats was calculated by direct sequencing of the PCR fragments. After sequencing, samples were decoded (Dowsing AT, et al., 1999).

The sons of these female carriers would have a 50% chance of being affected by the mutation, and therefore be infertile (Dowsing AT, et al., 1999).

Since the androgen-receptor gene was isolated and cloned, mutations in this gene have been associated with various disorders including complete androgen insensitive syndrome, various motor neuron diseases, and prostate and ovarian cancers as well. Many phenotypically norm

Some common words found in the essay are:
Lee SL, Nachtigall LB, Lower CAG, Expansion CAG, Asian Indian, Horne AW, , NGFI-A Egr-1, et al, cag repeat, et al 1999, dowsing et al, al 1999, dowsing et, androgen-receptor gene, sl et, lee sl, lb et, et al 1996, sl et al, lee sl et, expansion cag, al 1996,
Approximate Word count = 1379
Approximate Pages = 6 (250 words per page double spaced)