CytoCell Prenatal 13 and 21 Enumeration FISH Probe Kit

Probe specification

• 13 unique sequence, 13q14.2, Green
• 21 unique sequence, 21q22.1, Orange

The green probe mix contains a 124kb probe and a 416kb probe that spans the ITM2B, RB1 and RCBTB2 genes. The orange probe mix covers a region on 21q22.1 from the DYRK1A gene to the DSCR8 gene.

Probe information

Down Syndrome (DS) is an autosomal trisomy that is caused by the presence of a third (partial or total) copy of chromosome 21 and is characterised by variable intellectual disability, muscular hypotonia, and joint laxity, often associated with a characteristic facial dysmorphism and various anomalies such as cardiac, gastrointestinal, neurosensorial or endocrine defects^1,2. DS is one of the leading causes of intellectual disability worldwide and these patients also face various health issues including learning and memory, congenital heart diseases (CHD), Alzheimer’s diseases (AD), leukaemia, cancers and Hirschsprung disease (HD)¹. DS has high genetic complexity and phenotype variability¹. At 16 weeks gestation of pregnancy, the incidences of DS pregnancies are 1 in 1050 for mothers aged 20 years, 1 in 620 for mothers aged 30 years and 1 in 70 for mothers aged 40 years³.

Patau Syndrome (PS) is a chromosomal anomaly caused by the presence of an extra chromosome 13 and is characterised by brain malformations (holoprosencephaly), facial dysmorphism, ocular anomalies, postaxial polydactyly, visceral malformations (cardiopathy) and severe psychomotor retardation². PS is associated with phenotypic holoprosencephaly and midline fusion abnormalities due to defective fusion of the prechordal mesoderm in the embryonic stage⁴. At 16 weeks gestation of pregnancy, the incidence of PS pregnancies are 1 in 11 000 for mothers aged 20 years, 1 in 6500 for mothers aged 30 years and 1 in 700 for mothers aged 40 years³.

Intended purpose

The CytoCell^® Prenatal 13 and 21 Enumeration Probe Kit is a qualitative, non-automated, fluorescence in situ hybridisation (FISH) test used to detect the chromosome 13q14.2 region and the chromosome 21q22.1 region in Carnoy’s solution (3:1 methanol/acetic acid) fixed cells derived from amniotic fluid samples, in enumerating chromosomes 13 and 21 in high-risk pregnancies where Down or Patau syndrome are suspected.

Indications for use

This device is designed as an adjunct to other clinical and laboratory tests in recognised diagnostic and clinical care pathways, such as ultrasound screening and biochemical testing, where knowledge of the copy number status of the chromosome 13q14.2 region and the chromosome 21q22.1 region would be important for patient management.

Limitations

This device is designed to detect chromosomal material which includes the chromosome 13q14.2 and chromosome 21q22.1 regions covered by the green and orange clones in this probe set respectively. Genomic gains or losses outside these regions, or partial losses or gains of these regions may not be detected with this device.

This device is not intended for: use as a stand-alone diagnostic, use as a companion diagnostic, population-based screening, near-patient testing, or self-testing, and has not been validated for sample types, disease types, or purposes outside of those stated in the intended purpose.

This device is intended as an adjunct to other diagnostic laboratory tests and therapeutic action should not be initiated on the basis of the FISH result alone.

Reporting and interpretation of FISH results should be performed by suitably qualified staff, consistent with professional standards of practice, and should take into consideration other relevant test results, clinical and diagnostic information.

This device is intended for laboratory professional use only.

Failure to adhere to the protocol may affect the performance and lead to false positive/negative results.