developmental and epileptic encephalopathy, 90

Developmental and epileptic encephalopathy, 90 is a neurodevelopmental disorder that primarily affects brain function, leading to seizures and significant developmental delays. The disorder is caused by pathogenic variants in the FGF13 gene, which plays an important role in neuronal development and excitability. As an X‐linked condition, males tend to exhibit more severe symptoms, while affected females may experience milder manifestations due to variable X-inactivation. Precise prevalence estimates are not well established, and the condition typically presents in early childhood with notable cognitive and neurological features.

Individuals with developmental and epileptic encephalopathy, 90 often present with a range of neurological manifestations. Characteristic features include high-frequency focal-onset seizures, bilateral tonic-clonic seizures, and evidence of epileptiform activity on EEG such as burst suppression and hypsarrhythmia. In addition to these seizure types, many affected children demonstrate severe to profound global developmental delays, autistic behavior, limb hypertonia, hypotonia, ankle clonus, and a positive Babinski sign. After a period of apparently typical early development, affected children experience a phase of developmental regression marked by loss of previously acquired skills, although not all individuals experience all features and the severity varies considerably. Some patients may also have non-neurological issues including apneic episodes in infancy, atrial septal defect, abdominal pain, constipation, hypothyroidism, and even fetal pyelectasis.

Developmental and epileptic encephalopathy, 90 is caused by pathogenic variants in the FGF13 gene, which is vital for normal neuronal function and development. The condition is inherited in an X-linked pattern, meaning that the gene alteration is located on the X chromosome. Because males have only one X chromosome, they are generally more severely affected, while females may present with a milder form of the condition or variable symptoms due to differences in X-inactivation. Families are encouraged to seek genetic counseling to better understand the inheritance implications and the potential impact on family planning.

Currently, management focuses on supportive care and symptom management, as there are no FDA-approved treatments specifically linked to this condition. Treatment is tailored to the individual and typically involves a multidisciplinary team that may include pediatric neurology, developmental specialists, and genetic counselors. Regular surveillance is an essential part of long-term care, helping to identify potential complications early. Families should discuss treatment options with their healthcare team to determine which therapies may be appropriate, and genetic counseling is recommended to address inheritance concerns.

Outcomes for individuals with developmental and epileptic encephalopathy, 90 vary considerably depending on the severity of symptoms, age at diagnosis, and access to specialized care. The condition is characterized by a lifelong neurodevelopmental course that involves an initial phase of regression, often followed by a period of relative stabilization and, in some cases, later motor decline. Outcomes described in medical literature continue to evolve as standards of care improve, and it is important to recognize that severity and symptom presentation differ widely between individuals. Connecting with a genetic counselor and specialists experienced in managing neurodevelopmental conditions can provide valuable guidance for families.