title: Mild phenotype in two unrelated patients with a partial deletion of 21q22.2-q22.3 defined by FISH and molecular studies.
abstract: We describe two unrelated patients with cytogenetically visible deletions of 21q22.2-q22.3 and mild phenotypes. Both patients presented minor dysmorphic features including thin marfanoid build, facial asymmetry, downward-slanting palpebral fissures, depressed nasal bridge, small nose with bulbous tip, and mild mental retardation (MR). FISH and molecular studies indicated common deleted areas but different breakpoints. In patient 1, the breakpoint was fine mapped to a 5.2 kb interval between exon 5 and exon 8 of the ETS2 gene. The subtelomeric FISH probe was absent on one homologue 21 indicating a terminal deletion spanning approximately 7.9 Mb in size. In patient 2, the proximal breakpoint was determined to be 300-700 kb distal to ETS2, and the distal breakpoint 2.5-0.3 Mb from the 21q telomere, indicating an interstitial deletion sized approximately 4.7-7.3 Mb. The 21q- syndrome is rare and typically associated with a severe phenotype, but different outcomes depending on the size and location of the deleted area have been reported. Our data show that monosomy 21q of the area distal to the ETS2 gene, representing the terminal 7.9 Mb of 21q, may result in mild phenotypes comprising facial anomalies, thin marfanoid build, and mild MR, with or without signs of holoprosencephaly.
authors.affiliation: Praenadia GmbH, Muenster, Germany.
authors.forename: Daniela
authors.initials: D
authors.lastname: Ehling
authors.forename: Ingo
authors.initials: I
authors.lastname: Kennerknecht
authors.forename: Annelore
authors.initials: A
authors.lastname: Junge
authors.forename: Bettina
authors.initials: B
authors.lastname: Prager
authors.forename: Rita
authors.initials: R
authors.lastname: Exeler
authors.forename: Beate
authors.initials: B
authors.lastname: Behre
authors.forename: Juergen
authors.initials: J
authors.lastname: Horst
authors.forename: Thomas
authors.initials: T
authors.lastname: Schmitt-John
authors.forename: Oliver
authors.initials: O
authors.lastname: Bartsch
authors.forename: Jutta
authors.initials: J
authors.lastname: Wirth
mesh_terms: D001483:Base Sequence; D002872:Chromosome Deletion; D002891:Chromosomes, Human, Pair 21; D017931:DNA Primers; D005260:Female; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007231:Infant, Newborn; D007621:Karyotyping; D008297:Male; D009006:Monosomy; D010641:Phenotype
chemical_list: D017931:DNA Primers