title: Microdeletions within 22q11 associated with sporadic and familial DiGeorge syndrome.
abstract: DiGeorge syndrome (DGS) is a developmental field defect of the third and fourth pharyngeal pouches. It is associated with deletion of 22q11 in 11% of cases. Molecular genetic analysis with probes from 22q11-pter reveals that a subset of markers is hemizygous in DGS patients with normal karyotypes. There is no apparent difference in the phenotype or the severity of the disorder between patients with the smallest detectable submicroscopic deletion and those with the largest cytogenetically visible abnormality. A microdeletion was found in a mildly affected child and in the severely affected child of a mildly affected father. Dysmorphology, especially cardiac outflow tract anomalies, resulting from 22q11 deletion may be more common than currently realized since chromosomes are unlikely to be checked if the complete spectrum of DGS is not present. Antenatal diagnosis, through detection of hemizygosity at 22q11, will be a possibility for mildly affected parents unwilling to risk the birth of a severely affected child.
authors.affiliation: Department of Biochemistry and Molecular Genetics, St. Mary's Hospital Medical School, London, United Kingdom.
authors.forename: P J
authors.initials: PJ
authors.lastname: Scambler
authors.forename: A H
authors.initials: AH
authors.lastname: Carey
authors.forename: R K
authors.initials: RK
authors.lastname: Wyse
authors.forename: S
authors.initials: S
authors.lastname: Roach
authors.forename: J P
authors.initials: JP
authors.lastname: Dumanski
authors.forename: M
authors.initials: M
authors.lastname: Nordenskjold
authors.forename: R
authors.initials: R
authors.lastname: Williamson
mesh_terms: D002460:Cell Line; D002872:Chromosome Deletion; D002892:Chromosomes, Human, Pair 22; D003720:Densitometry; D004062:DiGeorge Syndrome / Q000235:genetics*; D005819:Genetic Markers; D006801:Humans; D009693:Nucleic Acid Hybridization; D010641:Phenotype
chemical_list: D005819:Genetic Markers