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[Hypotonic infants and the Prader-Willi Syndrome]
C Fridman1, F Kok, C P Koiffmann
1Universidade de São Paulo (USP), SP, Brazil.
Insights
Early diagnosis of Prader-Willi syndrome (PWS) in infants with severe hypotonia and poor sucking is possible through genetic analysis. This approach can identify PWS before obesity onset, avoiding unnecessary tests for neuromuscular disorders.
Area of Science:
- Genetics
- Pediatrics
- Endocrinology
Background:
- Prader-Willi syndrome (PWS) is a complex neurobehavioral disorder.
- PWS typically presents in two phases: early hypotonia and feeding issues, followed by hyperphagia and obesity.
- Diagnosis is often delayed until obesity develops, missing opportunities for early intervention.
Purpose of the Study:
- To describe PWS diagnosis in six young patients (under 3 years).
- To highlight the importance of early genetic analysis for PWS.
- To differentiate PWS from neuromuscular disorders in infants.
Main Methods:
- Genetic analysis including methylation, microsatellite analysis, and karyotyping.
- Traditional and in situ hybridization techniques were employed.
- Clinical evaluation of infants with hypotonia, poor sucking, and facial anomalies.
Main Results:
- Four patients had a deletion in chromosome segment 15q11q13.
- Two patients exhibited maternal disomy.
- Genetic abnormalities confirmed PWS in all six patients.
Conclusions:
- Early PWS diagnosis is crucial and can be achieved through genetic testing in infants with severe hypotonia, poor sucking, and characteristic facial features.
- Genetic analysis can prevent invasive and often inconclusive diagnostic procedures for neuromuscular disorders.
- Prompt diagnosis facilitates timely management and improves outcomes for children with PWS.
Abstract:
OBJECTIVE: To describe 6 patients with less than 3 years of age that were diagnosed with Prader-Willi syndrome (PWS) due to hypotonia, poor sucking, slight facial anomalies and minor abnormalities of hands and feet. PWS is a neurobehavioural disorder characterized by two distinct phases; in the first, the neonate presents variable degree of hypotonia, feeding problems with none or poor sucking; hypogonadism, characteristic facial features with almond shaped eyes, narrow bifrontal diameter and down-turned corners of the mouth. Neuropsichymotor development is delayed. Hypotonia is non progressive and tends to improve between 8 and 11 months of age. The second phase then starts and is characterized by increasing hyperphagia and obesity, among other features. Unfortunately, most PWS patients are diagnosed only after obesity is installed. METHODS: Methylation, microsatellites analysis and karyotypic studies by traditional and in situ hybridization techniques were done. RESULTS: A deletion of chromosome segment 15q11q13 was disclosed in 4 and maternal disomy in two patients. CONCLUSION: The diagnosis of PWS is generally established after the onset of obesity. So, we suggest that the genetic analysis must be carried out in children with severe hypotonia of unknown cause, poor sucking and some facial features of PWS (small hands and feet, hypogonadism, hypopigmentation, almond eyes and narrow bifrontal diameter). This can allow the early diagnosis and avoid invasive exams necessary for neuromuscular disorder diagnosis like muscle biopsy and electroneuromiography, wich frequently are associated with inconclusives results.