Examining Developmental Outcomes of Children Diagnosed With CLN2 Disease

CLN2 disease is a predominantly late infantile form of neuronal ceroid lipofuscinosis and one of the many genetic isoforms of Batten disease. Mutations in the CLN2 gene are characterized by deficient lysosomal serine protease TPP1, an enzyme that metabolizes intracellular lysosomal storage materials. Accumulations of intracellular deposits occur over time and in many organs of individuals with CLN2 disease and lead to neurodegeneration and, eventually, death. CLN2 disease is an extremely rare genetic disease affecting around 1 per 200,000 live births. Symptoms emerge early in life typically between the ages of 2 and 4 years of age and include seizures, as well as loss of motor, language, and vision functioning. Development further declines in early childhood and by age 6 years, children with CLN2 are often unable to walk or sit unsupported and become blind. The progression of the disease is rapid with death typically occurring in mid-childhood between the ages of 10 and 15 years of age. Recently, enzyme replacement therapy (ERT), cerliponase alfa, which is a recombinant form of human TPPI, was the first FDA-approved treatment to slow the progression of motor decline in children with CLN2. Cerliponase alfa is expected to restore TPP1 enzyme activity in the brain and alter neurodegeneration and disease progression. Animal models suggest promising treatment outcomes as cerliponase alfa significantly delayed the onset of clinical signs, preserved motor and cognitive function, and prolonged life. Initial results from a clinical trial further demonstrated that patients receiving cerliponase alfa had less motor declines, as measured by the CLN2 Clinical Rating Scale, compared to a natural history cohort. Despite these promising results, little is known about the trajectory of other developmental domains, including language, social-emotional, and adaptive functioning of children receiving cerliponase alfa. Likewise, the developmental trajectory of untreated patients with CLN2 is not well understood. Therefore, it is important to understand developmental outcomes and the progression of CLN2 in a natural history cohort in order to compare the effectiveness of treatment outcomes.