American Society for Clinical Pathology (ASCP) Technologist in Cytogenetics certification (ASCP CG) Practice Test

What tests should be ordered on a newborn suspected of having Prader-Willi syndrome?

1. Standard karyotype analysis

2. High resolution banding and FISH

3. MLPA analysis

4. Whole genome sequencing

The correct answer is: High resolution banding and FISH

High-resolution banding and FISH (Fluorescence In Situ Hybridization) are the most appropriate tests to order for a newborn suspected of having Prader-Willi syndrome. This syndrome is often associated with the loss of paternal genetic material on chromosome 15, which typically can be identified through specific genetic testing. The use of high-resolution banding allows for a detailed examination of chromosomes that may reveal deletions or other chromosomal anomalies related to Prader-Willi syndrome. Additionally, FISH techniques can be employed to detect specific deletions of the region on chromosome 15 that is commonly affected in this disorder. FISH can be particularly useful for finding the 15q11.2 region's deletion directly, providing a quick and reliable confirmation of the suspected diagnosis. While standard karyotype analysis can identify large chromosomal abnormalities, it may not reveal small deletions associated with Prader-Willi syndrome. MLPA (Multiplex Ligation-dependent Probe Amplification) and whole genome sequencing, though useful for other types of genetic analysis, may not be the first-line tests for this condition, as they could be more time-consuming or complex compared to the specific needs for detecting the chromosomal change associated with Prader-Willi syndrome.