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DNA methylation based testing of 450 patients suspected of having Prader-Willi syndrome
G Gillessen-Kaesbach1, S Gross, S Kaya-Westerloh
1Institut für Humangenetik, Universitätsklinikum Essen, Germany.
Insights
The PW71 methylation test effectively diagnoses Prader-Willi syndrome (PWS) in patients. This genetic test is crucial for identifying PWS, especially in infants with hypotonia, and can help differentiate it from other genetic conditions.
Area of Science:
- Genetics
- Molecular Biology
- Pediatrics
Background:
- Prader-Willi syndrome (PWS) is a complex genetic disorder characterized by developmental delays, distinct facial features, and hormonal abnormalities.
- Accurate and timely diagnosis of PWS is essential for appropriate management and intervention.
- Diagnostic challenges exist, particularly in infants with severe hypotonia and in differentiating PWS from other genetic syndromes.
Purpose of the Study:
- To evaluate the diagnostic utility of a DNA methylation test at the D15S63 (PW71) locus for Prader-Willi syndrome.
- To assess the accuracy of the PW71 methylation test in a cohort of patients with suspected PWS and infants with unexplained hypotonia.
Main Methods:
- Utilized a DNA methylation test targeting the D15S63 (PW71) locus for genetic analysis.
- Studied 385 patients (aged 1-36 years) for PWS diagnostic confirmation and 65 infants (aged 0-12 months) with severe hypotonia.
- Analyzed blood samples and patient examinations to assess methylation patterns and clinical phenotypes.
Main Results:
- The PW71 methylation test confirmed PWS in 28/58 personally examined patients and 112/327 externally referred samples.
- 29/65 hypotonic infants tested positive for PWS, indicating its utility in early diagnosis.
- Differential diagnoses were established for five patients lacking PWS but exhibiting abnormal methylation patterns.
Conclusions:
- The PW71 methylation test is highly effective in diagnosing typical Prader-Willi syndrome.
- PWS is frequently underdiagnosed in infants and misdiagnosed in obese or intellectually disabled individuals.
- The PW71 test aids in differential diagnosis, distinguishing PWS from other genetic syndromes.
Abstract:
Using a test based on parent of origin specific DNA methylation at the D15S63 (PW71) locus, we studied 385 patients (aged 1 to 36 years) for diagnostic confirmation of Prader-Willi syndrome (PWS) and 65 infants (aged 0 to 12 months) with severe hypotonia of unknown cause. Fifty eight of 385 patients were examined personally; 28/58 patients had PWS and lacked the paternal PW71 band and 30/58 patients, who did not have PWS, had a normal methylation pattern. In five of these patients, a differential diagnosis was made (Ohdo-like blepharophimosis syndrome, Alstrøm syndrome, Cohen syndrome, Bardet-Biedl syndrome, and pseudohypoparathyroidism). A total of 327/385 blood samples was sent to us from outside. The test confirmed the diagnosis of PWS in 112/327 patients. Most of the other 215 patients lacked the major diagnostic criteria such as neonatal hypotonia, feeding problems, characteristic facies, and hypogenitalism. On the other hand, 29/65 hypotonic infants tested positive for PWS. We conclude that the PW71 methylation test detects most, if not all, patients with typical PWS and that PWS is often not recognised in infants and wrongly suspected in obese and mentally retarded patients.
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