Congenital Hypotonia in a Child With a De Novo 22q13 Monosomy and 2pter Duplication: A Clinical and Molecular Genetic Study

Abstract

The authors describe a 5-year-old girl with a neurological phenotype of 22q13 deletion syndrome (neonatal and persisting hypotonia, developmental delay, absence of language, decreased perception of pain) and minor dysmorphisms. Subtelomeric fluorescent in situ hybridization tests revealed de novo 22q13 monosomy and 2pter duplication. Numerous genetic and neurologic disorders of childhood are characterized by congenital hypotonia. This muscle tone disorder is often one of the symptoms that a neurologist is asked to evaluate. Recent advances in genetic testing can help provide a specific diagnosis for children with this symptom. Subtelomeric deletions are a category of disorders of which hypotonia can be a prominent feature. Deletions of chromosome 22q13 are some of the most commonly observed terminal deletions in humans, whereas duplications of chromosome 2p25.2 are very rare, and little is known about the phenotypic effect of these duplications. To the best of the authors’ knowledge, this association has never been described before.