Pure and complete trisomy 18p due to a supernumerary marker chromosome associated with moderate mental retardation.
Trisomy for the short arm of chromosome 18 or trisomy 18p, is rarely described. We report on a 13-year-old boy with minor facial anomalies, mental retardation, bilateral cryptorchidism associated with a de novo supernumerary marker chromosome (SMC). Using fluorescence in situ hybridization and comparative genomic hybridization analyses, this SMC corresponded to the p arm of chromosome 18 associated with a centromere of either chromosome 13 or 21 and nucleolus organizing regions (NORs). We report here the first case of a pure and complete trisomy 18p due to a SMC. This report and review of literature confirm that the main phenotypic anomaly associated with trisomy 18p is moderate mental retardation.
Mabboux
P
P
Service d'Histologie Embryologie Cytogénétique, INSERM U782, Hôpital Antoine Béclère, APHP, Université Paris Sud, Clamart, France. philippe.mabboux@abc.aphp.fr
Brisset
S
S
Aboura
A
A
Pineau
D
D
Koubi
V
V
Joannidis
S
S
Labrune
P
P
Tachdjian
G
G
D000293:Adolescent; D002648:Child; D002887:Chromosomes, Human, Pair 18; D020732:Cytogenetic Analysis; D006801:Humans; D007223:Infant; D008607:Intellectual Disability / Q000235:genetics*; D008297:Male; D014314:Trisomy