TY - JOUR
T1 - Duplication of the Down syndrome critical region does not predict facial phenotype in a baby with a ring chromosome 21
AU - Crombez, Eric A.
AU - Dipple, Katrina M.
AU - Schimmenti, Lisa A.
AU - Rao, Nagesh
PY - 2005/10
Y1 - 2005/10
N2 - Ring chromosomes represent a rare type of chromosomal anomaly that can lead to multiple malformations. Although rings may occur with any chromosome, ring chromosome 21 is of particular interest due to the association of this chromosome with Down syndrome. Individuals with a ring chromosome 21, containing duplicated material, typically have a phenotype consistent with Down syndrome. We report an infant with a ring chromosome 21 containing a duplication of most of the long arm, including the Down syndrome critical region [46,XX,r(21)(p11.2q22.3)]. Fluorescence in situ hybridization analyses of the ring showed one chromosome 21 centromere, two copies each of the AML1 gene (q22) and the Down syndrome critical region, and deleted subtelomeric material. The patient has some Down syndrome characteristics including a high arched palate, a secundum atrial septal defect, and duodenal stenosis, but lacks the typical Down syndrome facial features, nuchal folds, and hand/foot anomalies. The phenotype of this patient supports the hypothesis that the duplication of the Down syndrome critical region alone is not sufficient to recapitulate the classical Down syndrome craniofacial phenotype.
AB - Ring chromosomes represent a rare type of chromosomal anomaly that can lead to multiple malformations. Although rings may occur with any chromosome, ring chromosome 21 is of particular interest due to the association of this chromosome with Down syndrome. Individuals with a ring chromosome 21, containing duplicated material, typically have a phenotype consistent with Down syndrome. We report an infant with a ring chromosome 21 containing a duplication of most of the long arm, including the Down syndrome critical region [46,XX,r(21)(p11.2q22.3)]. Fluorescence in situ hybridization analyses of the ring showed one chromosome 21 centromere, two copies each of the AML1 gene (q22) and the Down syndrome critical region, and deleted subtelomeric material. The patient has some Down syndrome characteristics including a high arched palate, a secundum atrial septal defect, and duodenal stenosis, but lacks the typical Down syndrome facial features, nuchal folds, and hand/foot anomalies. The phenotype of this patient supports the hypothesis that the duplication of the Down syndrome critical region alone is not sufficient to recapitulate the classical Down syndrome craniofacial phenotype.
KW - Down syndrome
KW - Down syndrome critical region
KW - Dysmorphology
KW - Ring chromosome
KW - Ring chromosome 21
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U2 - 10.1097/00019605-200510000-00003
DO - 10.1097/00019605-200510000-00003
M3 - Article
C2 - 16155419
AN - SCOPUS:25844508345
SN - 0962-8827
VL - 14
SP - 183
EP - 187
JO - Clinical Dysmorphology
JF - Clinical Dysmorphology
IS - 4
ER -