Severe neurodevelopmental phenotype with multisystem involvement in VPS16-related mucopolysaccharidosis-like syndrome.

Vacuolar protein sorting 16 (VPS16) functions in endolysosomal trafficking. Biallelic VPS16 variants cause a mucopolysaccharidosis-like syndrome reported in only four patients, with neurological involvement ranging from mild developmental delay to severe impairment with epilepsy and pyramidal signs. We report an additional patient biallelic for VPS16 NM_022575.4:c.2272-18 C > A, with profound developmental delay, early-onset epilepsy, and spasticity. Multisystem involvement included recurrent infections, neutropenia, serosal effusions, and tubular proteinuria. Brain MRI showed white-matter abnormalities, progressive cerebral and cerebellar atrophy, and symmetric signal changes in the globus pallidus and substantia nigra, suggestive of iron deposition, further expanding the neurological spectrum of this disorder.