4H syndrome is an autosomal recessive neurodegenerative disorder characterized by childhood onset of progressive motor decline manifest as spasticity, ataxia, tremor, and cerebellar signs, as well as mild cognitive regression. Dental manifestations are a delay in primary tooth eruption, a complete retention of the primary maxillary central incisors and shape abnormalities of the permanent maxillary central incisors and oligodontia. Other features may include hypogonadotropic hypogonadism. There is considerable inter- and intrafamilial variability.
4H syndrome is caused by homozygous or compound heterozygous mutation in the POLR3A gene (614258) on chromosome 10q22.
