Clinicoradiologic Features and Genetic Findings of Infantile Neuroaxonal Dystrophy

Infantile neuroaxonal dystrophy (INAD) is an extremely rare neurodegenerative disorder affecting 1 in 1 000 000 children. The PLA2G6 gene mutation is associated with infantile neuroaxonal dystrophy. Symptoms typically begin between 6 and 18 months of age, leading to neurodegeneration, particularly impacting motor skills. This article presents 7 pediatric cases (aged 12 months to 11 years) clinically and radiologically diagnosed with infantile neuroaxonal dystrophy, with at least 1 variation in the PLA2G6 gene. All patients show neurodegeneration, particularly in the motor area, with normal laboratory test results and a high rate of consanguinity among parents (6/7 patients). Clinical findings included spasticity or hypotonia, nystagmus in 3 patients, and ataxia in 1 patient, but none of them showed extrapyramidal signs. Major brain magnetic resonance imaging (MRI) findings include cerebellar atrophy and claval hypertrophy, as well as alterations in cerebellar hemisphere density and drooping splenium of the corpus callosum. The patients exhibiting nystagmus, hypotonicity, absent deep tendon reflexes, and drooping of the splenium of the corpus callosum demonstrated early initial clinical findings and had a poor prognosis. Six of the 7 patients have a homozygous variant, whereas 1 has a compound heterozygous variant. All patients are bedridden, and their Gross Motor Function Classification System score is 5. We emphasize that a patient who experiences neurodegeneration after 1 year of age, with normal laboratory test results and cerebellar atrophy observed on brain MRI, should be considered for infantile neuroaxonal dystrophy. Furthermore, we believe that the drooping splenium of the corpus callosum is one of the radiologic indicators of infantile neuroaxonal dystrophy, and early recognition of this disease can lead to accurate diagnosis, effective treatment plans, and genetic counseling.