[X-chromosomal recessive hydrocephalus internus: a separate disease picture? 2 further case reports and review of the literature].

Two patients with X-chromosomal hydrocephalus internus (aqueduct stenosis, clasped thumbs, mental retardation and spasticity) habe been described. In both cases the family history revealed further affected relatives. The intra- and interfamilial variability of this rare X-chromosomal recessive disease will be demonstrated. In this context differentialdiagnoses like X-linked MASA syndrome and X-linked spastic paraplegia have been discussed on the basis of a variable expressivity of different mutations in the same gene.