1/6. Interruption of the aortic arch at the isthmus with digeorge syndrome and 22q11.2 deletion.A 6-day-old male with interruption of the aortic arch at the isthmus (type A) had the typical phenotype of digeorge syndrome. There was also a doubly committed juxta-arterial ventricular septal defect and an unobstructed left ventricular outflow tract. Hypoplasia of the thymus was confirmed during a modified Blalock-Park operation. He had persistent hypocalcemia, and was susceptible to infection. He was subsequently revealed by the use of fluorescence in situ hybridization analysis to have 22q11.2 deletion. Interruption of the aortic arch at the isthmus is presumed to reflect abnormal fetal hemodynamics, and is considered a distinct pathogenetic entity from interruption between the left common carotid and subclavian arteries, the latter being the variant more frequently associated with digeorge syndrome. In our case, the 22q11.2 deletion likely played a major role in the etiology of the interrupted aortic arch.- - - - - - - - - - ranking = 1keywords = hybridization (Clic here for more details about this article) |
2/6. Possible third case of Lin-Gettig syndrome.We report a patient with craniosynostosis, severe mental retardation, absence of the corpus callosum, camptodactyly, hypogonadism, and ventricular septal defect. We propose that he has Lin-Gettig syndrome and that he is the third reported patient with this entity. Our patient also had additional phenotypic features, including palatal cleft and absent rapid eye movement (REM) sleep that were not present in the two previously described patients with this syndrome. High-resolution karyotype and subtelomeric fluorescence in situ hybridization (FISH) for cryptic telomeric rearrangement were normal. The existence of an unrelated patient with Lin-Gettig syndrome supports that this is a separate and distinct clinical entity.- - - - - - - - - - ranking = 1keywords = hybridization (Clic here for more details about this article) |
3/6. prenatal diagnosis of mosaic ring chromosome 22 associated with cardiovascular abnormalities and intrauterine growth restriction.OBJECTIVES: To present the prenatal diagnosis and perinatal findings of mosaic ring chromosome 22. CASE: amniocentesis was performed at 18 gestational weeks because of an advanced maternal age. cytogenetic analysis of the cultured amniotic fluid cells revealed mosaicism for ring chromosome 22, 45,XX,-22[6]/46,XX,r(22)(p13q13.31)[15]. Abnormal fetal sonographic findings included small for gestational age, a ventricular septal defect, and truncus arteriosus. The pregnancy was terminated. Additional phenotypic findings included hypertelorism, epicanthal folds, and abnormal ears. cytogenetic analysis of the cord blood lymphocytes revealed a complex mosaic karyotype, 45,XX,-22[7]/46,XX,r(22)(p13q13.31)[82]/46,XX,idic r(22)(p13q13.31;p13q13.31)[11]. cytogenetic analysis of the hepatocytes also revealed mosaic r(22) with mosaicism for idic r(22) and monosomy 22. The deletion of distal 22q and the duplication of 22q11.2 on idic r(22), and the distal 22q deletion on r(22) were demonstrated by fluorescent in situ hybridization (FISH) analysis using 22q terminal probes at 22q13 and a digeorge syndrome critical region probe at 22q11.2. The breakpoint on distal 22q13 and the extent of the duplication of 22q on idic r(22) was determined by examining polymorphic markers specific for chromosome 22 using quantitative fluorescent polymerase chain reaction assays. The chromosomal aberration was of maternal origin. CONCLUSION: Molecular and FISH studies allow a better delineation of some prenatally detected aneuploidy syndromes and help elucidate the genetic pathogenesis. Fetuses having mosaic r(22) with a low level mosaicism for r(22) duplication/deletion may present cardiovascular abnormalities and intrauterine growth restriction on prenatal ultrasound.- - - - - - - - - - ranking = 1keywords = hybridization (Clic here for more details about this article) |
4/6. parietal bone agenesis and associated multiple congenital anomalies.Congenital defects of the calvaria in general and the parietal bones in particular are rare diseases. The latter are of three kinds: 1) cranioschisis, 2) craniodysostosis, and 3) foramina parietalia permagna (FPP). Here, we describe an exceptional anomaly, namely, complete absence of one parietal bone and dysplasia of the other. Agenesis has been reported twice before in the literature. In these cases, the calvarial defect was the only congenital anomaly. In contrast, the patient described in this article exhibited many other congenital deformities, namely, iris coloboma, facial dysmorphism, a large ventricular septal defect of the heart, and a horseshoe kidney. Some of these deformities are associated with neural crest development. Chromosomal analysis was normal in both blood and fibroblasts, and fluorescent in situ hybridization analysis failed to demonstrate a 22q11 deletion as seen in digeorge syndrome, a neural crest-related disease complex. Since 2000, the third group of congenital defects of the parietal bones, FPP, has been associated with mutations of the MSX-2 gene. In our case, a genetic analysis of this gene was performed, but no mutations or deletions of MSX-2 were detected.- - - - - - - - - - ranking = 1keywords = hybridization (Clic here for more details about this article) |
5/6. Maternal uniparental disomy for chromosome 22 in a child with generalized mosaicism for trisomy 22.We report on a case of generalized mosaicism for trisomy 22. At chorionic villus sampling (CVS) in the 37th week of pregnancy, a 47,XX, 22 karyotype was detected in all cells. The indication for CVS was severe unexplained symmetrical intrauterine growth retardation (IUGR) and a ventricular septal defect (VSD) was noted. In cultured cells from amniotic fluid taken simultaneously, only two out of ten clones were trisomic. At term, a growth-retarded girl with mild dysmorphic features was born. lymphocytes showed a normal 46,XX[50] karyotype; both chromosomes 22 were maternal in origin (maternal uniparental disomy). Investigation of the placenta post-delivery using fluorescence in situ hybridization showed a low presence of trisomy 22 cells in only one out of 14 biopsies. In cultured fibroblasts of skin tissue, a mosaic 47,XX, 22[7]/46,XX[25] was observed. Clinical follow-up is given up to 19 months.- - - - - - - - - - ranking = 1keywords = hybridization (Clic here for more details about this article) |
6/6. Application of fluorescence in situ hybridization to the identification of different marker chromosomes.Chromosome studies performed on lymphocyte culture of a baby with specific dysmorphism and congenital anomalies suggestive of trisomy 21 revealed a mosaicism: 46,XY,rea(21q21q) [25]/47,XY,rea(21q21q), mar1[25]. The karyotype of the mother is normal, but the father's karyotype presents an supernumerary chromosome greater and different from the marker of his son: 47,XY, mar2 (100%). The identification of the two marker chromosomes by standard cytogenetic techniques followed by molecular techniques is essential for the identification of the origin of these two chromosomes. The unusual presence of two different markers one in the father and one in the son, as well as the clinical features of the child, are presented. The possible role of the paternal marker, in the de novo chromosomal rearrangement in his child will be discussed.- - - - - - - - - - ranking = 4keywords = hybridization (Clic here for more details about this article) |