title: Congenital hydrocephalus internus and aqueduct stenosis: aetiology and implications for genetic counselling.
abstract: Genetic counselling in families with congenital hydrocephalus internus (CHI) in combination with aqueduct stenosis (AS) is often difficult due to an uncertain aetiology. We present a series of 35 patients with CHI and AS focusing on the aetiology and presumed recurrence risk for siblings. In 13 patients (37.1%) a genetic aetiology was identified with an increased recurrence risk for siblings. The relative frequency of patients with X-linked hydrocephalus in our sample was in accordance with the literature (2/35), but was more frequent in other diseases with Mendelian inheritance.
  
  
  CONCLUSIONS
  In addition to the well-known X-linked and autosomal recessive forms of aqueduct stenosis with hydrocephalus, this malformation can occur in other diseases with Mendelian inheritance. This finding is of considerable importance for genetic counselling and prognosis.
authors.affiliation: Zentrum für Kinderheilkunde der Universität Bonn, Germany.
authors.forename: F
authors.initials: F
authors.lastname: Haverkamp
authors.forename: J
authors.initials: J
authors.lastname: Wölfle
authors.forename: M
authors.initials: M
authors.lastname: Aretz
authors.forename: A
authors.initials: A
authors.lastname: Krämer
authors.forename: B
authors.initials: B
authors.lastname: Höhmann
authors.forename: H
authors.initials: H
authors.lastname: Fahnenstich
authors.forename: K
authors.initials: K
authors.lastname: Zerres
mesh_terms: D002535:Cerebral Aqueduct / Q000473:pathology*; D003251:Constriction, Pathologic; D008040:Genetic Linkage; D005820:Genetic Testing; D006801:Humans; D006849:Hydrocephalus / Q000209:etiology / Q000235:genetics*; D007231:Infant, Newborn; D014960:X Chromosome