Genetic technologies are evolving rapidly and new tests may have become available since a patient last had contact with the Genetics Department.
Therefore, even in cases that appear to have a clear management pathway, contact and/or referral may result in the use of new technologies or tests.
Pre-implantation Genetic Diagnosis
Pre-implantation Genetic Diagnosis (PGD) is performed at two centres in London and one in Nottingham for couples at high risk of having a child with a severely disabling, or life threatening, single gene disorder, or for couples where one parent carries a balanced chromosome translocation with a high risk of producing a chromosomally unbalanced child (see below). PGD is not available for every single gene disorder.
Couples requesting PGD should be referred to the Northern Genetics Service for a preliminary discussion. If PGD is possible the family will be referred to one of the PGD centres for further discussion and assessment.
The PGD centre will apply to the PCT for funding on the couples behalf if they decide to go ahead. Approximately 50% of applications are currently funded.
Conditions for which PGD can be offered include:
Autosomal dominant conditions:
Autosomal recessive conditions:
X-linked inheritance:
Chromosomal conditions:
- Aneuploidy (unequal number of chromosomes)
- known translocations
Balanced Translocations:
A translocation is described as balanced if there is no extra or missing material within the chromosomes involved.
Either, two chromosomes swap pieces (a reciprocal translocation) or two whole chromosomes may become stuck together (a Robertsonian translocation).
Phenotypically, these individuals appear normal. However their offspring may inherit an unbalanced translocation, have extra or missing chromosomal material and be phenotypically affected. 3-4% of Down’s Syndrome cases are due to a one parent having a balanced translocation, and these families are at a high risk of having a second child affected with Down’s Syndrome.
