RIDDLE syndrome

The features of this condition include: • Facial dysmorphism • Short stature • Mild motor control and learning difficulties • Mild ataxia • Microcephaly • Normal intelligence • Conjunctival telangiectasia • Recurrent sinus infections • Decreased serum IgA • Late onset of pulmonary fibrosis • Increased alpha-fetoprotein • Increased radiosensitivity ==Genetics==

This condition is due to mutations in the RNF168 gene. It is inherited in an autosomal recessive fashion. The gene encodes a ubiquitin ligase and is located on the long arm of chromosome 3 (3q29) on the Crick (minus strand). ==Diagnosis==

Differential diagnosis The DDx is • Ataxia telangectasia • Artemis deficiency • Immunodeficiency 26 (PKCS gene deficiency) • LIG4 syndrome • Nijmegen breakage syndrome • Severe combined immunodeficiency with Cernunnos • X-linked agammaglobulinemia ==Management==

This condition is extremely rare. Only four cases have been described up to 2017. ==History==

This syndrome was first described by Stewart et al. 2007. == References ==