Meins M, Böhm D, Großmann A, Herting E, Fleckenstein B, Fauth C, Speicher MR, Schindler R, Zoll B, Bartels I, Burfeind P. First non-mosaic case of isopseudodicentric chromosome 18 (psu idic(18)(pter → q22.1::q22.1 → pter) Is associated with multiple congenital anomalies reminiscent of trisomy 18 and 18q− syndrome.
Am J Med Genet A 2003;
127A:58-64. [PMID:
15103719 DOI:
10.1002/ajmg.a.20644]
[Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Isopseudodicentric chromosome 18 is very rare and results in a combination of partial trisomy and partial monosomy of chromosome 18. We report here a hypotrophic newborn with a lateral cleft lip and palate and multiple craniofacial dysmorphisms, a combined heart defect, unilateral hypoplasia of the kidney, bilateral aplasia of thumbs, and generalized contractures. Cytogenetic analysis revealed an isopseudodicentric chromosome 18 with breakpoint in 18q (46,XX,psu idic(18)(pter --> q22.1::q22.1 --> pter)). The isopseudodicentric chromosome 18 was observed in 100% of blood lymphocytes and umbilical cord fibroblasts, thus indicating a non-mosaic finding of the isopseudodicentric chromosome in the child. An elongated derivative chromosome 18 had also been found prenatally in amniotic cells. In contrast, a terminal deletion (18q-) was detected in placental cell cultures. The breakpoint was mapped to a 0.9 Mb region on 18q22.1 (located 64.8-65.7 Mb from the telomere of the p-arm) by a novel quantitative PCR approach with SYBR green detection. The results indicate an identical breakpoint of the isopseudodicentric chromosome 18 in the child and the 18q- chromosome in the placenta. To our knowledge this is the first report that a fetus carrying an isopseudodicentric chromosome 18 with breakpoint in 18q (46,XX,psu idic(18)(pter --> q22.1::q22.1 --> pter)) in non-mosaic form can be viable, but is associated with severe congenital malformations of the child.
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