Postnatal Cytogenetics

Postnatal Cytogenetics:

Approx. 820 samples per annum (2011)

Postnatal constitutional analysis is performed on venous blood samples. The most suitable test (and therefore the sample requirement) depends on the type of rearrangement being tested for. Referrals can be broadly divided into two main groups:

gband

malemeta

Potentially unbalanced karyotypes (physical or mental anomaly):

Referral categories include:

Mental retardation or developmental delay; dysmorphism, facial anomaly and congenital abnormality

First line test:

Oligonucleotide array CGH (molecular cytogenetics)

Sample requirement:

2-5ml EDTA blood, well-mixed

Routine reports:

Available within four weeks

Urgent reports:

Please enquire

 

Possible balanced rearrangements (reproductive difficulties):

Referral categories include:

Infertility; recurrent pregnancy loss; family studies

First line test:

G-banded chromosome analysis (conventional cytogenetics)

Sample requirement:

2-5ml lithium-heparin blood, well-mixed to prevent clotting (FISH studies can also be carried-out on this sample)

Routine reports:

Available within 28 days

Urgent reports:

Available within 10 days

Referrals are via general practitioners, or specialist clinics. Urgent samples would include neonates, parents of an ongoing pregnancy or specific clinical requests.

Cytogenetic studies may provide a diagnosis in cases of mental retardation or congenital abnormality, or may reveal familial rearrangements responsible for recurrent pregnancy loss. Liaison with the clinical genetics team allows patients to benefit from counselling, with respect to prognosis for the affected individual, and risks of recurrence for other family members

Sample requirements:

Blood samples should be dispatched promptly to the department (with an appropriate request form) to be received on the day of sampling, or the following day. Samples in an incorrect tube or delayed in transit are unlikely to yield a result. Samples of 1-2ml are acceptable from neonates. Cord blood is also acceptable.