Table 3 Genetic testing used in Prader-Willi syndrome
From: Recommendations for the diagnosis and management of childhood Prader-Willi syndrome in China
Methods | Genotype identified | Uses and limitations |
|---|---|---|
MS-MLPA | Paternal deletion, mUPD, ID, Robertsonian translocation | It can identify > 99% of PWS and can distinguish deletion from other types, but cannot generally distinguish mUPD from an ID (IC deletion and epimutation), unless in rare individuals, a microdeletion of the IC is seen. It also can estimate the size and distinguish most the paternal deletion subtype |
MS-PCR | Paternal deletion, mUPD, ID, Robertsonian translocation | It can identify > 99% of PWS, but it cannot distinguish molecular type. It can’t identify IC deletion and key gene pathogenic variant |
CMA-SNP array | Paternal deletion, partial mUPD (Isodisomy), | It can identify 80%-90% of PWS and provide information regarding deletions and duplications in the entire chromosome. However, it cannot distinguish the PWS from AS alone. It cannot identify partial mUPD (heterodisomy), ID, Robertsonian translocation and chromosomal rearrangements |
FISH | Paternal deletion, Robertsonian translocation | It can identify 65%–75% of PWS, and distinguish paternal deletions from chromosomal rearrangements (e.g. Robertsonian translocation). It may be used for patient’s parents to identify translocation. However, it cannot distinguish normal, mUPD, and ID, and requires living cells |
DNA sequence | IC deletion, pathogenic variant, most paternal deletion | It cannot identify mUPD and epimutation. It can be considered for rare situations after DNA methylation analysis, FISH (no deletion), quantitative microsphere hybridization |
High-resolution karyotype | Partial paternal deletions, Robertsonian translocation | It may detect most deletions, but requires experienced technician. It should not be used alone because it will miss some deletions, mUPD and ID |