A new case of 2q duplication supports either a locus for orofacial clefting between markers D2S1897 and D2S2023 or a locus for cleft palate only on chromosome 2q13-q21.
We report on a pure duplication of the proximal chromosome 2q in a 6.5-year-old boy with V-shaped midline cleft palate and bifid uvula, posteriorly located tongue, and micrognathia (Pierre Robin sequence), celiac disease, failure to thrive, and developmental delay. Cytogenetic and FISH analysis indicated a duplication of chromosome 2q13-q22. In general, pure proximal duplication or triplication of 2q is rare. The clinical features and chromosomal breakpoints of the 10 previously reported patients varied, and no common phenotype or proximal duplication/triplication 2q syndrome could be defined to date. However, based on four previous patients with different orofacial clefts and our case, a locus for orofacial clefting may be located at proximal 2q. The duplication/triplication comprised chromosome 2q13 in all five affected individuals including our patient. Our patient and three previous cases (two with cleft palate only (CPO) and one with cleft lip/palate (CL/P)) showed a cytogenetic breakpoint at 2q13, which could support the presence of a critical dominant gene disrupted by a common breakpoint, however, the fifth case with CPO showed different breakpoints, advocating against the disruption of a critical dominant gene and supporting that the overexpression of a gene(s) on chromosome 2q13-q21 may cause cleft palate only (CPO) and Pierre Robin sequence. Hence, our findings support either the presence of one locus for orofacial clefting (CL/P, CPO, and Pierre Robin sequence) between markers D2S1897 (chromosome 2q12.2) and D2S2023 (chromosome 2q14.2), or alternatively the presence of a locus for CPO and Pierre Robin sequence on chromosome 2q13-q21.
Ounap
Katrin
K
Medical Genetics Center, United Laboratories, Tartu University Clinics, Tartu, Estonia. katrin.ounap@kliinikum.ee
Ilus
Tiiu
T
Laidre
Piret
P
Uibo
Oivi
O
Tammur
Pille
P
Bartsch
Oliver
O
D000015:Abnormalities, Multiple / Q000235:genetics* / Q000473:pathology; D002446:Celiac Disease / Q000473:pathology; D002648:Child; D002869:Chromosome Aberrations; D002871:Chromosome Banding; D002889:Chromosomes, Human, Pair 2 / Q000235:genetics*; D002972:Cleft Palate / Q000473:pathology*; D002658:Developmental Disabilities / Q000473:pathology; D005183:Failure to Thrive / Q000473:pathology; D020440:Gene Duplication; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007621:Karyotyping; D008297:Male; D008844:Micrognathism / Q000473:pathology; D018895:Microsatellite Repeats; D014059:Tongue / Q000002:abnormalities; D014609:Uvula / Q000002:abnormalities