CDKL5 Deficiency Disorder Added to WHO International Classification of Diseases


The unique CDKL5 deficiency disorder diagnostic code will be incorporated in the October 1, 2020 classification revision.

Ana Mingorance, PhD

Ana Mingorance, PhD

The World Health Organization (WHO) has designated a new, unique disease code for CDKL5 deficiency disorder (CDD), which will be added to the International Classification of Diseases (ICD).

“Obtaining an ICD-10 code for CDD is a big milestone for our field and one more step towards having approved therapies and ensuring patient access to these treatments," said Ana Mingorance PhD, chief development officer at the Loulou Foundation, a non-profit foundation for CDD therapeutic development which spearheaded the ICD-10 code effort, in a statement.

The ICD is currently in its tenth revision. The new diagnostic code will help to facilitate clinical research and care, as well as improve billing and reimbursement related to health insurance. The CDD diagnostic code will be incorporated into the ICD revision set to be published on October 1, 2020.

The rare neurodevelopmental disorder stems from loss-of-function mutations in the CDKL5 gene. Patients with CDD experience frequent seizures shortly after birth and severe impairment in neurological development. Other symptoms of the disorder include impaired sleep, gastrointestinal function, and respiratory issues.

In 2018, the LouLou Foundation and the International Foundation for CDKL5 Research (IFCR) submitted a proposal for an unique code for CDD, claiming that the existing codes do not capture the multisystem effects of CDD. Numerous medical organizations, including the American Epilepsy Society (AES), American Academy of Neurology (AAN), and the Child Neurology Foundation (CNF) submitted letters in support of the proposal, as well as additional support from several pharmaceutical companies and patient advocacy organizations such as the National Organization for Rare Diseases.

The proposal was ultimately accepted and CDD was granted a unique ICD-10 code (G40.42).

The decision follows a Patient-Focused Drug Development meeting with the FDA that took place on November 1, 2019, where caregivers shared their stories and expressed future expectations from the regulatory agency.

“One of the reasons why we requested a code for CDD is because there are 4 ongoing clinical trials for therapies that might treat the disease, including a clinical study in the latest stage before approval. With an ICD-10 code for CDD, everything from research to reimbursement will become more efficient,” Mingorance said in a statement.

Notably, one trial is examining ganaxolone, a drug that has proved to be effective for the treatment of status epilepticus,(NCT03572933), and another trial is evaluating the efficacy of fenfluramine, a drug currently FDA approved for Dravet syndrome (NCT03861871).


Rare disease CDKL5 deficiency disorder granted WHO disease classification [news release]. London, UK. LouLou Foundation. January 27, 2020. Accessed January 28, 2020.

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