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Male infertility – chromosome and genetic investigation

Male infertility investigation Melbourne

Chromosome and Genetic Studies

Chromosomal anomalies are 8-10X more common in infertile than fertile populations, and in many cases there are no other  changes. A routine assessment is recommended in men with unexplained infertility and low sperm count  < 5-10 million/ml.  A karyotypes – chromosome picture is performed in men with clinical evidence of  testicular failure and small testes to confirm a clinical diagnosis of Klinefelter syndrome. Usually the karyotype is 47,XXY, but there may be higher numbers of X chromosomes or a sex-reversal 46,XX karyotype. Although most men with Klinefelter syndrome produce no sperm in the semen, some have low sperm count and very rarely fertile. Also, sperm for IVF-ICSI may be obtained by testicular biopsy in about 50%-80% of patients. Abnormal sperm production may occur with 47,XYY, but the clinical picture is much less uniform than it is for Klinefelter syndrome. Children generally have normal karyotypes. However, an increased rate of sex chromosomal and autosomal aneuploidy has been noted in studies of sperm from XXY and XYY men.

Infertile men have much higher rate of aneuploidies compared to fertile men and most of them have no other phenotypic features. An increased frequency of autosomal abnormalities is found with defective spermatogenesis, particularly balanced autosomal translocations (reciprocal and Robertsonian), which may be transmitted in unbalanced form to their offspring. As part of their infertility investigation, it is imperative to screenmen with very low sperm count as the result may affect treatment outcome.

 

Cystic fibrosis gene studies are important for evaluation of patients with congenital absence of the vas and their partners. If the woman has a cystic fibrosis gene mutation, preimplantation genetic diagnosis PGD of their embryos can be offered. Microdeletions in the long arm of the Y chromosome (AZF regions) have been found in 3% to 15% of men with severe primary spermatogenic disorders. Sons of men with these microdeletions have the same microdeletions.

 

Androgen receptor defects have also been found in some men with unexplained abnormal sperm.

 

At present, it is reasonable to screen all infertile men with otherwise unexplained abnormal sperm and low sperm count with average sperm concentrations less than 5-15 million/mL by karyotype and Yq microdeletion testing.

Dr Barak will arrange all necessary semen analysis tests, blood test and ultrasound scan.