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Prader-Willi syndrome: clinical and molecular cytogenetic investigations
Insights
Diagnosing Prader-Willi syndrome (PWS) is crucial for genetic counseling. Fluorescence in situ hybridization (FISH) is more reliable than high-resolution chromosome analysis for detecting PWS deletions.
Area of Science:
- Genetics
- Pediatrics
- Medical Diagnostics
Background:
- Prader-Willi syndrome (PWS) presents with neonatal hypotonia and feeding issues, progressing to hyperphagia, obesity, developmental delay, and hypogonadism.
- Accurate diagnosis of PWS is vital for clinical management and essential genetic counseling for affected families.
Purpose of the Study:
- To evaluate the efficiency of different diagnostic methods for Prader-Willi syndrome.
- To compare high-resolution chromosome analysis with fluorescence in situ hybridization (FISH) for PWS diagnosis.
Main Methods:
- Evaluated 37 patients with suspected Prader-Willi syndrome using clinical and molecular cytogenetic analyses.
- Utilized high-resolution chromosome analysis and fluorescence in situ hybridization (FISH) with specific probes (D15S11, GABRB3, SNRPN, D15S10).
Main Results:
- Clinical evaluation confirmed PWS criteria in 25 patients.
- Cytogenetic analysis identified deletions in 15q11.2-13 in 20 patients; FISH detected 4 additional cases.
- SNRPN deletion was confirmed in 24 PWS patients, with one case lacking detectable deletion.
Conclusions:
- Fluorescence in situ hybridization (FISH) offers a more reliable diagnostic method for Prader-Willi syndrome compared to high-resolution chromosome analysis.
- Associated contiguous gene syndrome effects contribute to high morbidity, emphasizing the need for genetic counseling and dietary management.
Abstract:
Prader-Willi syndrome is characterized by hypotonia and feeding difficulties in the neonatal period, with the childhood development of hyperphagia leading to obesity, developmental delay, hypogonadism, short stature and small hands and feet. Correct diagnosis of Prader-Willi syndrome is important because of its clinical implications and the need for family genetic counseling. In order to determine the most efficient method of diagnosing the condition, we evaluated 37 patients with a putative diagnosis of Prader-Willi syndrome by both clinical and molecular cytogenetic analyses. Clinical evaluation showed that 25 patients fulfilled the diagnostic criteria for Prader-Willi syndrome. A deletion of the region 15q11.2-13 was cytogenetically identified in 20 patients using a high-resolution technique. Four additional cases were detected by fluorescence in situ hybridization (FISH) with the cosmid probes for D15S11, r-aminobutyric acid receptor beta 3 (GABRB3), small nuclear ribonucleoprotein-associated peptide N (SNRPN) or D15S10 (Prader-Willi/ Angelman syndrome region probes). The deletion of SNRPN was documented in 24 Prader-Willi syndrome patients. Only one additional patient with typical Prader-Willi syndrome features did not have any deletion over 15q11-13 at either the cytogenetic or molecular level. FISH provides a more reliable method than high-resolution chromosome analysis for the diagnosis of Prader-Willi syndrome. Associated conditions such as hypopigmentation, small-joint laxity, arachnodactyly, seizure disorder, optic atrophy, congenital heart disease, Perthes' disease, hirsutism, astigmatism/amblyopia, microcephaly and neuropsychiatric disturbances dictate the effects of a contiguous gene syndrome. Morbidity is high among patients with obesity and associated conditions. Appropriate genetic counseling should be given to the parents and dietary management should be helpful for patients with Prader-Willi syndrome.