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.
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.
Meins
M
M
Institute of Human Genetics, University of Göttingen, Germany.
Böhm
D
D
Institute of Human Genetics, University of Göttingen, Germany.
Großmann
A
A
Department of Pediatrics, University of Göttingen, Germany.
Herting
E
E
Department of Pediatrics, University of Göttingen, Germany.
Fleckenstein
B
B
Department of Obstetrics and Gynecology, University of Göttingen, Germany.
Fauth
C
C
Institute of Human Genetics, Technical University München and GSF, National Research Center for Environment and Health, Neuherberg, Germany.
Speicher
M R
MR
Institute of Human Genetics, Technical University München and GSF, National Research Center for Environment and Health, Neuherberg, Germany.
Schindler
R
R
Institute of Human Genetics, University of Göttingen, Germany.
Zoll
B
B
Institute of Human Genetics, University of Göttingen, Germany.
Bartels
I
I
Institute of Human Genetics, University of Göttingen, Germany.
Burfeind
Peter
P
Institute of Human Genetics, University of Göttingen, Germany.
D000015:Abnormalities, Multiple / Q000175:diagnosis* / Q000235:genetics*; D000328:Adult; D000782:Aneuploidy; D019457:Chromosome Breakage / Q000235:genetics; D002887:Chromosomes, Human, Pair 18 / Q000235:genetics*; D002971:Cleft Lip / Q000235:genetics; D002972:Cleft Palate / Q000235:genetics; D020732:Cytogenetic Analysis; D005260:Female; D005312:Fetal Blood / Q000166:cytology; D005347:Fibroblasts / Q000166:cytology; D006801:Humans; D007231:Infant, Newborn; D008214:Lymphocytes / Q000166:cytology; D008297:Male; D032681:Spectral Karyotyping; D013577:Syndrome; D014314:Trisomy / Q000235:genetics