Genetics and Infertility
Genetics and Male infertility
It has been observed for more than 25 years that male infertility can be seen in association with genetic abnormalities.
As a consequence molecular genetic and cytogenetic analysis can be useful in the investigation of severe male infertility.
Y Micro-deletions
A method called PCR can be used for screening a large number of sites on the Y-chromosomes for micro-deletions. Although not fully understood, many infertile men have gaps in regions of their Y chromosome concerned with spermatogenesis.
In many cases, the same deletions are not seen in the fathers of the infertile men.
Importantly though, the condition can be passed on to infertile men's sons conceived through ICSI.
Cystic Fibrosis and Azospermia
Men who are about to undertake testicular biopsy (TESE) may be advised to have a blood test for the detection of the gene responsible for cystic fibrosis.
Cystic Fibrosis is a multi-system disorder affecting the pulmonary, gastrointestinal, and reproductive systems.
Patients affected with Cystic Fibrosis suffer from a wide range of diseases and are under frequent medical attention.
It is the most common recessive gene mutation with a frequency of 1 in 2500 births.
Research has shown a high percentage of men with non-obstructive azospermia are carriers for the Cystic fibrosis gene. "Mol. Human Repro." In Ápril,1998.
The prevention of CF has special importance in the field of reproductive medicine:
Due to the breakthrough of intracytoplasmic sperm injection (ICSI) in 1992, whereby a single spermatozoa is injected directly into the oocyte with high success it now possible to treat men with severely impaired sperm parameters through IVF.
In males where no sperm is present in the ejaculate often-mature sperm can be retrieved and microinjected from a testicular biopsy (Testicular sperm extraction or TESE).
As increasing numbers of males with infertility are choosing to be treated by assisted fertilization methods, genetic counseling and screening for CF becomes relevant.
Partners of Cystic Fibrosis positive males should also be tested for the most common Cystic Fibrosis so that prenatal or preimplantation diagnosis can be offered in the event of both partners being carriers.
Karyotyping
Karyotyping has become an important step in the diagnosis and management of males with severe oligospermia or azospermia.
Certain conditions can lead to implantation failure or miscarriage.
Genetics and female infertility
Chromosomal rearrangements can be a cause of unexplained infertility and premature ovarian failure- investigation may be recommended by your clinician.
Recurrent miscarriage testing may be investigated by karyotyping of both parents.
Pre-implantation genetic Diagnosis (PGD)
Pre-implantation genetic Diagnosis (PGD) is the detection of genetic defects or disease in embryos derived from In Vitro fertilization (IVF) after which the unaffected embryos are transferred into the uterus. The aim of PGD as a form of early prenatal diagnosis is avoidance through selection of embryos. In this way a couple at risk of having a child with a genetic disorder can initiate a pregnancy knowing that the child is not affected.
PGD aims to eliminate the risk for genetically disadvantaged couples, eliminate the period of time for prenatal diagnosis and subsequent psychological trauma the couple may face with the decision of a selective abortion.
PGD may be a solution to couples unwilling to undergo voluntary abortion for ethical or religious reasons.
The technique is not particularly new. The first children born were in 1989 at Hammersmith Hospital.
Collaboration with The Medical Genetics Department at St. Sophia's Children's Hospital provides PGD for B-thalassaemia and Cystic Fibrosis.
Since 1998 many children have been born from this technique. (Kanavakis, E., Vrettou, C., Palmer. G.A. et al, 1999).
