Abstract
Hypotonia is sometimes a diagnosis for which infants are referred for investigation in the neonatal period.. Hypotonia occurs in infants with different disorders: neuromuscular, metabolic and chromosomal disorders. Among chromosomal disorders, hypotonia is a differential diagnosis particularly in Down and Prader Willi syndromes. Thus, karyotyping and fluorescent in situ hybridyzation with specific probes should be considerd if a child is hypotonic and/or dysmorphic. In our laboratory, since almost two years, we have begun a study in neonates and children under six months referred for hypotonia. The aim of this study is to detect very early in infancy children with Prader Willi syndrome. For each case, routine chromosome analysis is performed. In all cases. When no cytogenetic chromosomal abnormalities have been found, a fluorescent in situ hybridyzation technique with SNRPN probe has been performed. The SNRPN probe detect 75 % of deletion in the Prader Willi syndrome region, the 25% of undected cases needed more investigation by other molecular techniques like research of maternal uniparental disomy The results showed that in cases referred only for hypotonia, around 15 % of cases have a microdeletion on chromosome 15 q11.2. The results showed a significative detection rate for pursuing the use of fluorescent in situ hybridyzation in cases of hypotonia in neonates and children under six months of age. The early detection in Prader Willi syndrome is very important because children with Prader Willi syndrome develop a morbid obesity and complication resultin from this obesity. Management is aimed at prevention of obesity and treatment of its consequence.
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Bérubé, D., Gagné, R. Hypotonia and Prader Willi syndrome in the neonatal period. Genet Med 1, 66 (1999). https://doi.org/10.1097/00125817-199901000-00100
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DOI: https://doi.org/10.1097/00125817-199901000-00100