Neurodevelopmental and neurological features in children with hypochondroplasia

Hypochondroplasia is a genetic skeletal dysplasia caused by variants in the FGFR3 gene. Although it is primarily recognized as a condition affecting bone growth and stature, there is increasing evidence that some children may also experience neurological and neurodevelopmental difficulties. We reviewed the medical records of 44 children with molecularly confirmed hypochondroplasia attending a specialist skeletal dysplasia service. We examined neurological features, neurodevelopmental outcomes, educational support needs, and brain MRI findings. Among children who underwent brain MRI, hippocampal malrotation was common. Seizures occurred in a small proportion of children. Neurodevelopmental and educational needs were also frequently identified. More than 70% of school-aged children required special educational needs (SEN) support, and almost 30% had an Education, Health and Care Plan (EHCP), a legal document used to provide additional educational support. Around one in five children had a diagnosed neurodevelopmental disorder. Specific learning disorders were more common than expected when compared with population estimates. These findings suggest that hypochondroplasia should not be considered solely a condition of skeletal growth. Neurodevelopmental and neurological difficulties appear to be more common than previously recognized and may have an important impact on educational outcomes and day-to-day functioning.