1/5. Newborn infant with inherited ring and de novo interstitial deletion on homologous chromosome 22s.A 2-day-old infant was evaluated and suspected of having 22q11.2 deletion based on microcephaly, short and narrow palpebral fissures, a prominent nose with hypoplastic alae nasi, thin fingers, and a right aortic arch. He also had an imperforate anus, which is not in the del 22q11.2 syndrome. karyotype analysis identified a ring 22, while fluorescence in situ hybridization (FISH) for the digeorge syndrome critical region identified a 22q deletion on the other homologue. The karyotype designation was 46,XY,r(22)(p13q13.3).ish del(22)(q11.2q11.2) (D22S75-). Both parents function in the mildly mentally retarded range. The father's karyotype was normal whereas the mother had the ring 22 that was inherited by her son. This is the first case reported for abnormalities on both 22 homologues.- - - - - - - - - - ranking = 1keywords = hybridization (Clic here for more details about this article) |
2/5. Usefulness and limitations of FISH to characterize partially cryptic complex chromosome rearrangements.Interpretation of a complex chromosome rearrangement (CCR) using only G-band analysis is difficult and potentially inaccurate. We present two patients with de novo, partially cryptic, CCRs that illustrate both the value and limitations of using fluorescence in situ hybridization (FISH) whole chromosome paint probes to characterize these types of rearrangements. In a patient referred because of features of Townes-Brocks syndrome, G-band analysis revealed an unbalanced CCR involving 3 chromosomes (2,11 and 16) and at least 4 breakpoints. A more complex rearrangement involving two cryptic insertions and at least 6 breakpoints, however, was detected using whole chromosome paint probes specific for the 3 chromosomes involved in the rearrangement. In this case, FISH studies were essential for accurate characterization of this patient's rearrangement. In a second patient, G-band analysis revealed that a 12-year-old male with obesity, small genitalia, attention deficit disorder, learning disabilities, and behavior problems, carried a CCR involving 4 chromosomes (3, 5, 10 and 13) with 6 breakpoints. This rearrangement seemed unbalanced, with missing terminal 3p26. 2-pter material. Our G-band interpretation of this karyotype was confirmed by FISH using whole chromosome paint probes specific for the involved chromosomes. Although no evidence of the "missing" 3pter material was observed using a chromosome 3 paint, FISH analysis using a chromosome 3p unique telomere probe identified telomeric 3p material on the distal long arm of the derivative 10 chromosome. This case illustrates the limited value of painting probes to detect small rearrangements, especially those involving terminal chromosome regions.- - - - - - - - - - ranking = 1keywords = hybridization (Clic here for more details about this article) |
3/5. Caudal dysplasia sequence with penile enlargement: case report and a potential pathogenic hypothesis.The clinical spectrum of caudal dysplasia sequence (CDS) is noted for its diversity. The origin of CDS remains unknown, though poorly controlled gestational diabetes has been implicated in some cases. Here we describe the case of a newborn with CDS associated with penile enlargement (PE). The main anomalies included anal atresia, agenesis of the kidneys and of the sacrococcygeal vertebrae, dysgenesis of lumbar vertebrae, and bilateral cryptorchidism. Penile enlargement (7 cm), a rather unusual finding, has so far not been reported in association with CDS. Chromosomal analysis failed, and the neonate died 30 min after birth. comparative genomic hybridization analysis using stored dna showed a balanced normal male dna content, which negates chromosomal losses or gains as a cause of CDS and/or PE. PE due to virilizing-type adrenal hyperplasia, caused by common mutations in the genes encoding for the adrenal enzymes 21-hydroxylase and 11-hydroxylase, was ruled out. We report on a previously unpublished case of the coexistence of PE and severe CDS and propose a possible pathogenetic hypothesis of this association. copyright Wiley-Liss. Inc.- - - - - - - - - - ranking = 1keywords = hybridization (Clic here for more details about this article) |
4/5. Deletion involving the TWIST locus and the HOXA cluster: a contiguous gene syndrome on 7p?Deletion of TWIST on 7p21 leads to Saethre-Chotzen syndrome, whereas deletion of the HOXA cluster on 7p15.2 leads to hand-foot-genital syndrome. We report here a patient with 46,XY,del(7)(p15.2p21) who had craniosynostosis, maxillary hypoplasia, prominent ear crus, rectoperineal fistula, and hypoplastic fifth fingers. Using fluorescence in situ hybridization, we demonstrated the deletion to encompass the TWIST locus and the HOXA cluster. We suggest that many, if not all, of the features of this patient could be accounted for by combined haploinsufficiency of the TWIST and HOXA cluster. Hence, the patient's phenotype may define a new contiguous gene syndrome on 7p.- - - - - - - - - - ranking = 1keywords = hybridization (Clic here for more details about this article) |
5/5. Parental origin of the extra chromosome in the cat eye syndrome: evidence from heteromorphism and in situ hybridization analysis.Two individuals, a boy and girl, with a clinical diagnosis of cat eye syndrome had an extra bisatellited chromosome. In the girl, the diagnosis was made on the basis of coloboma of the right iris, right preauricular pit, and imperforate anus; in the boy, bilateral colobomata of the iris, down-slanting palpebral fissures, right preauricular skin tag, and right preauricular pit. Multiple staining techniques were used to characterize the extra chromosomes. With G-banding the extra chromosome usually appeared monocentric with two major G-positive bands, but with satellites on both ends; with C-banding, two C-band positive regions were evident, indicating that the chromosomes were likely dicentric. silver staining demonstrated the presence of NORs near each end; Q-banding showed satellites on each end, differing in brightness and size. The chromosomes of the parents were normal; comparisons of Q-band heteromorphisms of the acrocentric chromosomes of the parents with those of the extra chromosome showed in each case one short arm/satellite region of the extra chromosome identical in appearance to one chromosome 22 of the mother and the other end of the extra bisatellited chromosome identical to the short arm/satellite of the mother's second chromosome 22. This extra chromosome, then, is the result of a maternal meiotic error in each case. in situ hybridization studies using the chromosome 22-derived probe p22/34, which identifies locus D22S9, showed 16% of the cells from the female patient to have silver grains on the proximal long arm of the normal chromosome 22 and 14% on the extra chromosome, while 10% of cells from the male had grains on the normal chromosomes 22 and an equal number on the extra chromosome, confirming the chromosome 22 origin of the extra chromosome in these patients.- - - - - - - - - - ranking = 5keywords = hybridization (Clic here for more details about this article) |