AIM: To report one patient with slowly progressive encephalopathy, ataxia, 
central hypomyelination, hypodontia and hypogonadotropic hypogonadism, the 4H 
syndrome. This clinical picture has been described recently and there are only 
four patients reported previously.
CASE REPORT: A girl with a previously normal early psychomotor development, 
presented a slowly progressive deterioration since 15 months of age. Now, she is 
14 years old, and has a severe cerebellar ataxia, with tremor and dysmetria. She 
can't neither walk nor remain standing alone. She has lost the sphincter control 
and has an immature expressive language. She has no puberal development and 
definitive hypodontia of upper central incisors. The brain magnetic resonance 
imaging shows a diffuse hypomyelination, that is confirmed with diffusion and 
spectroscopy studies.
CONCLUSION: The hypomyelinating leukoencephalopathies are disorders with 
abnormally low amount of myelin. The diagnosis is difficult in most of the 
patients. The hypomyelinating leukoencephalopathies include classic disorders 
and new leukoencephalopathies, described in the past few years.