Indications for Chromosome Analysis
- Dysmorphic features and/or developmental delay.
- Fetal or neonatal death with multiple congenital abnormalities or dysmorphic features.
- Indeterminate gender or ambiguous genitalia; amenorrhoea; infertility; or other suspected sex chromosome abnormality (e.g. Turner or Klinefelter syndrome).
- Known familial chromosome rearrangement.
- Known or suspected family history of chromosome abnormality where the karyotype of the affected individual is not known.
- Terminated fetus, for confirmation of an abnormal cytogenetic result diagnosed prenatally or in fetus suspected of having a chromosome abnormality (e.g. multiple markers diagnosed on ultrasound).
Prenatal diagnosis (following amniocentesis, chorionic villus biopsy, or fetal blood sampling) is available for the following indications.
- High risk of aneuploidy from the result of a screening programme as defined by the UK National Steering Committee (NSC) current standards.
- Ultrasound detection of any major structural abnormality including nuchal translucency (NT) >3mm before 14 weeks gestation or a nuchal fold measuring 6mm or greater between 14 and 20 weeks gestation.
- Ultrasound detection of two or more minor markers of aneuploidy. Consistent with NSC guidelines, Karyotyping should not be offered on a single marker in women who have a low risk following aneuploidy screening.
- History of chromosome abnormality indicative of increased risk for future pregnancies. Chromosome abnormality may be present in:
- The woman or her partner.
- A previous pregnancy (excluding non-viable aneuploidy).
- If there is a family history karyotyping of the woman or her partner should be undertaken first in order to establish whether prenatal diagnosis is indicated.
- Non-routine cases not fulfilling the above criteria after discussion and agreement between the referring clinician and the Head of Laboratory.
QFPCR screening for common aneuploidies but not routine karyotyping will be performed on all prenatal samples received for molecular and/or biochemical analysis – sample size permitting.
Please see Information For Users for full details.