Experience with the Ketogenic Diet in a Boy with CLCN4 Related Neurodevelopmental Disorder.

Raynaud-Claes syndrome is rare condition characterized with intellectual disability and is caused by X-linked pathogenic variants in CLCN4 gene. Hemizygous missense variant NM_001830.4: c.1597G>A (p.V533M) was detected in a 6-year-old male followed up with intellectual disability, dysmorphism, and epileptic encephalopathy. The mother and one sister of the patient were also carrying the same variant. The clinical picture of the patient was significantly more severe, and the patient exhibited nonconvulsive status. Tonic status was observed with benzodiazepine treatment and the patient was successfully treated with a ketogenic diet. Many types of seizures can be seen in Raynaud-Claes syndrome, some of which can be life-threatening. CLCN4 variants can be investigated in patients who exhibit an increase in tonic seizures with benzodiazepine treatment. However, ketogenic dietary therapy as first-line treatment can be lifesaving in resistant epilepsy cases caused by the CLCN4 gene.