New Magnetic Resonance Imaging (MRI) findings in a patient with hypochondroplasia caused by the FGFR3 N540K variant

A 7-year-old boy with hypochondroplasia had neurodevelopmental delay, mild cognitive impairment, subtle motor deficits and without epilepsy. There was no obstetric problem or perinatal impairment. Genetic revealed the p.N540K FGFR3 variant. MRI findings are depicted. FGFR3 regulates chondrocyte proliferation and differentiation and is instrumental in cortical patterning and neurogenesis. Temporal lobe dysgenesis is common in FGFR3-related hypochondroplasia. Squared and enlarged lateral ventricles, with reduced peritrigonal white matter (WM) have been described, but periventricular WM hyperintensities on T2/FLAIR weighted images, as demonstrated here, were not reported previously. Such WM lesions expand the neuroimaging signature in FGFR3-related hypochondroplasia.