PWS and AS is detected by a molecular genetic method called Methylation Sensitive HRM PCR. A microarray should also be performed as microarray testing detects all currently known microdeletion syndromes in one assay and can also determine the exact region deleted. A microarray is especially recommended when the diagnosis of PW or AS is not certain, or in very young paediatric cases. Microarray testing will detect ~70% of PWS or AS, ie. all cases caused by chromosome 15 deletion and some cases caused by UPD(15). Please refer to our testing algorithm for guidance - see resources below.
FISH testing is useful in the following situations:
1. Family follow-up where the syndrome has been shown previously to be caused by a deletion, to identify other affected relatives or to rule out the rare possibility of a parental balanced rearrangement involving the PWS/AS locus.
2. When the diagnosis is firm and urgency is required.
3. When methylation PCR has confirmed the diagnosis, but microarray testing has not been consented. FISH will only detect 15q11q13 deletion and not UPD(15).
Genetics
CTGN
15q11-q13 Deletion
Angelman syndrome
PWS testing
SNRPN Gene Deletion
28 days
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