Abstract
Cornelia de Lange syndrome (CdLS) is a rare neurodevelopmental disorder characterized by distinct dysmorphic facies, skeletal anomalies, and failure to thrive. CdLS type 5 (CdLS5) is caused by the HDAC8 gene mutations on chromosome Xq13.1 with X-linked dominant inheritance. We report our observation of an individual with CdLS5 with de novo missense mutation presenting with a novel phenotype of generalized dystonia. A four-month-old girl, second born to a non-consanguineous couple, presented with developmental delay, failure to thrive, and spastic quadriparesis. She had a history of intrauterine growth retardation in the third trimester of pregnancy. Facial gestalt was suggestive of CdLS. She had marked axial and appendicular dystonia. A skeletal survey and magnetic resonance imaging (MRI) with magnetic resonance spectroscopy (MRS) brain studies were normal. Genetic testing revealed a heterozygous missense variation c.628G>C in the HDAC8 gene. She was treated with trihexyphenidyl and clonazepam, followed by syndopa. On follow-up assessment at 22 months of age, the dystonia gradually improved but not entirely over time with medication. It is already known that single gene disorders, including SCN1A, SCN2A, KCNQ2, PRRT2, and pyridoxine deficiency, can result in isolated dystonia; we add CdLS5 (HDAC8 variation) to this expanding spectrum.