Edwards Syndrome

Introduction

Edwards Syndrome (trisomy 18), occurs in approximately 1 in 5000 live births. It is caused by an additional chromosome 18 or extra chromosome 18 material, including the critical region at 18q11-q12. The main features of Edwards syndrome include low birth weight, abnormally shaped head (microcephaly), hypotonia, characteristic facial features (such as small jaw, upturned nose, widely spaced eyes and malformed ears), rockerbottom feet, overlapping fingers and other congenital abnormalities of the heart, brain, kidneys, digestive tract and genitals. Many infants with trisomy 18 die within the first month and only 10% survive to one year. Although free trisomy 18 occurs sporadically, there is an increased risk of an Edwards syndrome pregnancy with increasing maternal age. Trisomy 18 may also appear in a mosaic form, where normal cells are also present in the individual. These individuals may exhibit a milder phenotype, which is dependent on the extent and tissue distribution of the normal cell line.

Referral information

For prenatal referrals we accept samples from women that have a high risk (>1:150) following antenatal screening including Combined or Quadruple testing, a family history of a chromosome rearrangement predisposing to trisomy 18, a previously affected pregnancy, or ultrasound scan findings indicative of trisomy 18. For postnatal samples we accept referrals from patients with appropriate clinical features for a diagnosis of trisomy 18 or for the confirmation of a prenatal diagnosis.

Price & reporting times

NHS referrals to this service are paid for where there is an existing specialist commissioning contract for genetic testing. In other cases please contact the lab for prices.

Test Price (£ ex VAT) TRT *
QF-PCR POA 3 cd
G-banded prenatal chromosome analysis POA 14 cd
Prenatal or neonatal microarray analysis POA 14 cd
G-banded neonatal chromosome analysis POA 10 cd

Test validation & quality assurance - information for users

The QF-PCR test is for trisomy 13, 18, 21 only and will not detect mosaicism or structural rearrangements. Rarely, testing may be uninformative or fail to give a result either due to maternal cell contamination or other factors. Maternal and paternal blood samples may be requested to help interpret results. Microarray analysis will not detected balanced rearrangements and may not detect mosaicism. Maternal cell contamination is excluded for prenatal samples prior to microarray testing by analysis of a maternal blood sample. This laboratory participates in the CEQAS quality assessment scheme for this test.

Sample requirements

Pre-natal (serum screening): amniotic fluid (minimum 10ml)/chorionic villus biopsy (CVB) (minimum 10mg) sample plus 4ml EDTA maternal blood sample

Referral guidelines

Please see our referral guidelines for more information.

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