title: Counselling dilemmas associated with the molecular characterisation of two Angelman syndrome families.
abstract: We report the molecular characterisation of two families with Angelman syndrome referred for prenatal diagnosis, in which atypical molecular findings resulted in counselling dilemmas. The first is a familial case of Angelman syndrome in which the two affected children have mutations which affect the imprinting mechanism, as shown by the presence of paternal DNA methylation patterns at D15S63 and SNRPN and biparental inheritance of 15q11-q13 markers. DNA prepared from a 21 week fetal blood sample detected a fetus with normal maternal and paternal DNA methylation patterns at D15S63, but inheritance of the same maternal chromosome 15q11-q13 as the two affected sibs. This is probably a result of germline mosaicism in the mother. The second is a case of Angelman syndrome with an atypical deletion of 15q11-q13, which involves both unusual proximal and distal breakpoints. The deletion was characterised in order to assess the risk of Angelman syndrome in a second pregnancy in the mother of this child.
authors.affiliation: Division of Biochemistry and Genetics, Institute of Child Health, London, UK.
authors.forename: H L
authors.initials: HL
authors.lastname: Gilbert
authors.forename: J L
authors.initials: JL
authors.lastname: Buxton
authors.forename: C T
authors.initials: CT
authors.lastname: Chan
authors.forename: T
authors.initials: T
authors.lastname: McKay
authors.forename: S
authors.initials: S
authors.lastname: Cottrell
authors.forename: S
authors.initials: S
authors.lastname: Ramsden
authors.forename: R M
authors.initials: RM
authors.lastname: Winter
authors.forename: M E
authors.initials: ME
authors.lastname: Pembrey
authors.forename: S
authors.initials: S
authors.lastname: Malcolm
mesh_terms: D017204:Angelman Syndrome / Q000235:genetics*; D002884:Chromosomes, Human, Pair 15; D019175:DNA Methylation; D015247:Deoxyribonuclease HindIII / Q000378:metabolism; D019003:Deoxyribonuclease HpaII / Q000378:metabolism; D005260:Female; D017353:Gene Deletion; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D008297:Male; D018895:Microsatellite Repeats; D010375:Pedigree; D011218:Prader-Willi Syndrome / Q000235:genetics; D011247:Pregnancy
chemical_list: D015247:Deoxyribonuclease HindIII; D019003:Deoxyribonuclease HpaII