developmental and epileptic encephalopathies dee epidemiology forecast

Developmental and Epileptic Encephalopathy Insights and Trends

• Developmental and Epileptic Encephalopathy (DEE) refers to a group of severe epilepsies that are characterized both by seizures, which are often drug-resistant, as well as encephalopathy, which is a term used to describe significant developmental delay or even loss of developmental skills.
• The syndromes of epileptic encephalopathies with onset in the neonatal period, infancy, and early childhood include early myoclonic encephalopathy, Ohtahara syndrome, West syndrome, Dravet syndrome (severe myoclonic epilepsy in infancy), Lennox–Gastaut syndrome (LGS), Landau–Kleffner syndrome (LKS), Epilepsy with continuous spike-and-waves during slow-wave sleep (ECSWS), Doose Syndrome (myoclonic atonic epilepsy), CDKL5 deficiency disorder (CDD), Tuberous sclerosis complex (TSC), SCN8A-DEE, and KCNQ2-DEE.
• Prevalence growth is primarily driven by improved recognition of genetic etiologies and wider use of advanced diagnostics (e.g., genetic testing) rather than a true rise in incidence, reflecting earlier diagnosis and expanded identification of DEE subtypes
• Incomplete genetic resolution (with many causative mutations still unidentified) contributes to a substantial hidden burden of undiagnosed or misdiagnosed patients
• Mutation-specific variability results in uneven disease severity and progression, impacting overall burden distribution.
• Developmental and Epileptic Encephalopathies (DEE) are a major contributor to severe early-onset epilepsy and neurodevelopmental impairment, leading to lifelong disability and significant socioeconomic burden, while the development of patient registries is improving epidemiological understanding and clinical research, although global data remains limited and heterogeneous.
• DEE shows a generally gender-neutral distribution (with variability across genetic syndromes), with onset in infancy or early childhood due to diverse genetic etiologies, and a persistent prevalence driven by chronic disease course and improved survival with better care.
• In DEE, the increasing use of genetic testing is improving diagnostic accuracy, although the true burden remains underestimated due to underdiagnosis, limited access to specialized care, and heterogeneous clinical presentation.

Developmental and Epileptic Encephalopathy Epidemiology Forecast in the 7MM

• 2025 Diagnosed Prevalent Cases of Developmental and Epileptic Encephalopathy: ~287,806
• DEE Growth Rate (2026–2036): ~1.2% CAGR

DelveInsight's ‘Developmental and Epileptic Encephalopathy – Epidemiology Forecast – 2036’ report delivers an in-depth understanding of the DEE, historical and forecasted epidemiology in the United States, EU4 (Germany, Spain, Italy, and France) and the United Kingdom, and Japan.

Developmental and Epileptic Encephalopathy Understanding and Diagnosis Algorithm

DEE Overview and Diagnosis

Developmental and Epileptic Encephalopathy (DEE) is a group of severe, often drug-resistant epilepsies characterized by frequent seizures and significant developmental delay or regression caused by underlying genetic or structural abnormalities, with abnormal brain activity further worsening outcomes; it includes syndromes such as Dravet, Lennox–Gastaut, CDKL5 deficiency, and SCN-related disorders. Diagnosis is based on clinical history, neurological examination, EEG, imaging (MRI/CT), and genetic or blood tests to confirm epilepsy type, identify the underlying cause, guide treatment selection, and assess associated developmental or behavioral impairments.

Further details are provided in the report.

Developmental and Epileptic Encephalopathy Epidemiology

Key Findings from DEE Epidemiological Analysis and Forecast

• In the 7MM, the total diagnosed prevalent population of DEE is expected to rise from 287,806 (2025) to 326,850 (2036) at a CAGR of 1.2%.
• In the 7MM, the United States contributed to the largest diagnosed prevalent population of DEE, acquiring ~ 51% of the 7MM in 2025. The total diagnosed prevalent population of DEE in the United States is expected to rise from 146,541 in 2025 to 167,297 by 2036 at a CAGR of 1.2%. Whereas, EU4 and the UK accounted for 37% and Japan for 12% of the total prevalent population, in 2025.
• In 2025, the total diagnosed prevalent cases of DEE in Japan were 33,604, which is anticipated to increase to 38,049 cases by 2036.
• In 2025, the total diagnosed prevalent population of DEE in EU4 and the UK was 107,660, which is projected to increase to 121,504 by 2036. Germany accounted for the highest number of diagnosed prevalent cases of DEE, i.e. 35,070 cases, while Spain accounted for the least number of cases (13,672) in 2025.  These cases are expected to increase with a CAGR of 1.1%.

Scope of the Report

• The report covers a segment of an executive summary, a descriptive overview of DEE, explaining its causes, signs and symptoms, and pathogenesis.
• Comprehensive insight has been provided into the epidemiology segments and forecasts, the future growth potential of the diagnosis rate, and disease progression.

Report Insights

• DEE Patient Population Forecast

Report Key Strengths

• Epidemiology-based (epi-based) Bottom-up Forecasting
• 11-year Forecast
• Patient Burden Trends (by Geography)

FAQs

• What are the disease risks, burdens, and unmet needs of DEE? What will be the growth opportunities across the 7MM concerning the patient population with DEE?
• What is the historical and forecasted DEE patient pool in the US, EU4 (Germany, France, Italy, and Spain), the UK, and Japan?

Reasons to Buy

• Insights on patient burden/disease prevalence, evolution in diagnosis, and factors contributing to the change in the epidemiology of the disease during the forecast years.
• To understand key opinion leaders’ perspectives around the diagnostic challenges to overcome barriers in the future.
• Detailed insights on various factors hampering disease diagnosis and other existing diagnostic challenges.