A case report of X-linked CDKL5 gene variant in monozygotic twins associated with developmental and epileptic encephalopathy-2

CDKL5 (Cyclin‐Dependent Kinase Like-5) deficiency disorder (CDD; Online Mendelian Inheritance in Man database 300203, 300672) is a rare neurologic disorder, which is caused by mutation in CDKL5 gene, situated on the X chromosome. Therefore, this condition is inherited in an X-linked dominant pattern. In general, this gene provides instruction for making a protein that is essential for normal brain development and plays an important regulatory role in neuronal function. We report a case of 2.5-year-old monozygotic twins (female), Twin-1 is found to be affected with CDKL5 deficiency disorder; development and epileptic encephalopathy-2; DEE2. The symptoms started at approximately 4 months of age. Current study aims to stratify risk using NGS (next generation sequencing) in both the parents and Twin-2. This case highlights the importance of genetic testing in patients with genetic disorder for proper diagnosis, for better treatment/management and to understand the prognosis of the condition. Together with the clinical and genetic information, genetic counselling of the patient/patient’s parents can help them in taking informed decision.