1/17. Ring chromosome 22 and autism: report and review.Ring chromosome 22 has been described in over 50 cases. A characteristic phenotype has not been fully delineated; however, long face, thick eyebrows, 2-3 toe syndactyly, mental retardation, adequate somatic growth and the absence of major malformations are noted in many cases. An 11-year-old boy with ring chromosome 22 and 46,XY,r(22)(p11.31-q13.31 approximately q13.33) karyotype presented with global developmental delay, autistic disorder, and dolichocephaly, apparently low-set and large ears, midface hypoplasia, and 2-3 toe syndactyly. This is the second report of a ring chromosome 22 with autistic disorder. There appears to be an association between abnormalities of chromosome 22, including r(22), and autistic disorder; however, this occurrence may be a result of the association of autistic disorder with mental retardation rather than specifically due to r(22). The physical findings in this case also suggest that ring chromosome 22 causes a subtle but distinct phenotype which has previously been proposed.- - - - - - - - - - ranking = 1keywords = physical (Clic here for more details about this article) |
2/17. Cytogenetical dose estimation for 3 severely exposed patients in the JCO criticality accident in Tokai-mura.A dose estimation by chromosome analysis was performed on the 3 severely exposed patients in the Tokai-mura criticality accident. Drastically reduced lymphocyte counts suggested that the whole-body dose of radiation which they had been exposed to was unprecedentedly high. Because the number of lymphocytes in the white blood cells in two patients was very low, we could not culture and harvest cells by the conventional method. To collect the number of lymphocytes necessary for chromosome preparation, we processed blood samples by a modified method, called the high-yield chromosome preparation method. With this technique, we could culture and harvest cells, and then make air-dried chromosome slides. We applied a new dose-estimation method involving an artificially induced prematurely condensed ring chromosome, the PCC-ring method, to estimate an unusually high dose with a short time. The estimated doses by the PCC-ring method were in fairly good accordance with those by the conventional dicentric and ring chromosome (Dic R) method. The biologically estimated dose was comparable with that estimated by a physical method. As far as we know, the estimated dose of the most severely exposed patient in the present study is the highest recorded among that chromosome analyses have been able to estimate in humans.- - - - - - - - - - ranking = 1keywords = physical (Clic here for more details about this article) |
3/17. Stable ring chromosome 21: molecular and clinical definition of the lesion.Ring chromosome 21 results in deletions of chromosome 21. We report on a cytogenetic and molecular analysis of a 4-generation family segregating a stable ring chromosome 21 in 4 relatives. To investigate the molecular structure of the ring chromosome, we have analyzed the DNAs of the transmitted ring in a mother and her daughter. The daughter presented at the age of 2 years with severe growth retardation and microcephaly, whereas her mother had microcephaly but normal intelligence. High resolution chromosome analysis of both cases showed the ring chromosome to be r(21)(p13q22) resulting in deletions of 21p and 21q22. The molecular content of the ring chromosome was determined using quantitative Southern blot analyses of 5 random dna sequences and 4 expressed genes assigned to chromosome 21 and mapping in the region of q22.3. We have shown that collagen type VI, alpha 2 (COL6A2,) S100 protein, beta polypeptide (neural), (S100B), and D21S44 are present in only one copy in both ring carriers, while CRYA1, CBS, D21S43, D21S42, D21S41, and D21S39 are present in two copies. These data and the breakpoints defining the deletion in these patients show that deletion of COL6A2 and S100B is compatible with normal function and confirm the physical map of 21q22.3 by placing COL6A2, S100B, and D21S44 in very distal 21q22.3. patients with such small deletions provide unique models for understanding the biological and clinical significance of aneuploidy for specific expressed genes.- - - - - - - - - - ranking = 1keywords = physical (Clic here for more details about this article) |
4/17. Ring chromosome 17. Case report and review of the literature.A 46,XX,r(17) karyotype was observed in a 9-year-old infant with short stature, moderate mental retardation but without other physical abnormality. Eight cases with an r(17) have since been reported: 4 can be compared with our patient, one was detected by amniocentesis, and 3 have Miller-Dieker syndrome. Submicroscopic deletions in the subband p13.3 are probably the cause of Miller-Dieker syndrome. They are present in some cases of r(17) but, in others, this short arm region is entirely preserved.- - - - - - - - - - ranking = 1keywords = physical (Clic here for more details about this article) |
5/17. FOXC1 gene deletion is associated with eye anomalies in ring chromosome 6.We report a case of ring chromosome 6 presenting with growth and mental retardation, cerebral dysgenesis, eye malformations, mixed hearing loss, and abnormal physical features. Fluorescent in situ hybridization (FISH) and microsatellite genotyping demonstrated segmental deletions of less than 6 Mb on 6p and 1-2 Mb on 6q. The primary karyotype is designated as 46,XY,r(6)(p25q27).ish r(6)(p25.1q27)(D6S344-, FOXC1-, D6S1574 , D6S281-, D6S297 ). Secondary structural and numerical variants of the ring 6 were observed in 16% of the cells analyzed. Intragenic genotyping revealed deletion of the paternal FOXC1 gene, haploinsufficiency of which has been reported to cause eye anterior chamber developmental defects. Accordingly, we propose that our patient's ophthalmologic abnormalities result from haploinsufficiency of the transcription factor FOXC1. We present clinical and cytogenetic summaries on 23 reported cases of ring 6 and categorize them into mild, moderate, and severely affected groups. Further phenotype comparisons between cases with ring 6 and cases with only 6p or 6q terminal deletions suggest that genes important for hearing, vision, and central nervous system development remain to be identified in chromosome 6 terminal regions. Molecular definition of the fusion points and tissue mosaicism studies are necessary to better understand the genotype-phenotype correlation of ring 6. We recommend ophthalmology, audiology, cardiology, and central nervous system examinations be part of the routine evaluation for children with a ring chromosome 6.- - - - - - - - - - ranking = 1keywords = physical (Clic here for more details about this article) |
6/17. A case of ring chromosome 22 with deletion of the 22q13.3 region associated with agenesis of the corpus callosum, fornix and septum pellucidum.We report a 16-week-gestation foetus obtained by voluntary abortion after prenatal diagnosis, in which a ring chromosome 22 was observed with deletion of the 22q13.3 region. A prenatal study of the amniotic fluid by standard chromosome technique with G bands and FISH (fluorescence in situ hybridisation) was performed. After the abortion, the anatomopathological study of the obtained foetus was carried out. Morphological and histological analysis of the foetus did not reveal severe physical abnormalities, although alterations of the nervous system were observed consisting of corpus callosum, fornix and septum pellucidum agenesia. It could be that the genes in this region that were involved in the development of the central nervous system were responsible for the alterations found in the morphological study. The wide range of manifestations observed in patients with this cytogenetic alteration is probably due to size differences in the deleted region.- - - - - - - - - - ranking = 1keywords = physical (Clic here for more details about this article) |
7/17. Inherited ring chromosome 8 without loss of subtelomeric sequences.We report the first case of inherited ring chromosome 8 syndrome without loss of subtelomeric sequences. The proband is a 6 1/2-year-old boy with short stature, microcephaly, mild mental retardation, and behavioral problems including hyperactivity and attention deficit. His mother presented the same physical features but intelligence was normal. family history also revealed an uncle and a grandmother, with short stature and microcephaly. Moderate mental retardation was reported in the uncle. Karyotypes and fluorescence in situ hybridization (FISH) analyses were performed on peripheral blood lymphocytes for both child and mother. The child's karyotype was reported as 46,XY,r(8)(p23q24.3)[24]/45,XY,-8[2] and the mother's karyotype 46,XX,r(8)(p23q24.3)[22]/45,XX,-8[2]/47,XX,r(8)(p23q24.3), r(8)(p23q24.3)[1]. FISH studies showed no deletion of subtelomeric sequences for both child and mother indicating that no or little chromosomal euchromatic material has been deleted. These findings indicate that ring chromosome 8 without loss of subtelomeric sequences can be inherited and that carriers in a same family present with cognitive function ranging from mild mental retardation to normal intelligence.- - - - - - - - - - ranking = 1keywords = physical (Clic here for more details about this article) |
8/17. Characterization of a small supernumerary marker chromosome as r(8) at prenatal diagnosis by MFISH.OBJECTIVE: To identify the mosaic marker chromosome detected in amniotic fluid cells of a 26-year-old woman, with raised triple test values and an ultrasound scan, which showed a fetus with echogenic bowels. methods: Routine karyotyping with G- and C-banding was carried out for both, amniotic fluid at 18 weeks of gestation as well as fetal blood at 22( 6) weeks. Peripheral blood of both parents was karytoyped. MFISH and the all centromeric human probe were used on fetal lymphocytes to identify the marker chromosome. RESULTS: Both parents had a normal karyotype. amniotic fluid culture showed a de novo supernumerary marker chromosome (SMC) in 14 of the 30 colonies from four different cover slip cultures. The marker was confirmed in 50% of the fetal lymphocytes. G- and C-banding provided little information except that the marker had some heterochromatic material. The all centromeric human probe also showed the presence of a centromere along with a rim of euchromatic material. MFISH identified this ring marker to be belonging to chromosome 8. CONCLUSIONS: SMCs with chromosome 8 have been shown to be variable phenotypes. Presence of only heterochromatic material seems to have no discernable phenotypic effects, but, with the presence of euchromatic material, mental and physical developmental delay has been reported. The parents opted to go ahead with the pregnancy and an apparently normal female baby was born at 40 weeks with no complications.- - - - - - - - - - ranking = 1keywords = physical (Clic here for more details about this article) |
9/17. Microdeletion in the SHOX 3' region associated with skeletal phenotypes of Langer mesomelic dysplasia in a 45,X/46,X,r(X) infant and Leri-Weill dyschondrosteosis in her 46,XX mother: implication for the SHOX enhancer.It is known that SHOX nullizygosity results in Langer mesomelic dysplasia (LMD) and SHOX haploinsufficiency leads to Leri-Weill dyschondrosteosis (LWDC). Here, we report on a microdeletion in the SHOX 3' region identified in a Japanese infant with LMD-compatible skeletal features and a 45,X[191]/46,X,r(X)(p22.3q24)[9] karyotype and in her mother with LWDC-compatible skeletal features and a normal 46,XX karyotype. Physical and auxological examinations revealed mesomelic appearance, ulnarly deviated hands, and borderline micrognathia in the infant, and relatively short forearms and lower legs in the mother. Radiological studies indicated mesomelia, markedly curved radii, hypoplastic ulnas and fibulas, and metaphyseal splaying in the infant, and borderline to mild curvature of the radii, decreased carpal angles, and high-normal triangularization index in the mother. Cytogenetic and molecular studies showed that the ring x chromosome of the infant was missing SHOX and of paternal origin, whereas the cytogenetically normal X chromosomes of the infant and one of the two X chromosomes of the mother, though they retained SHOX with normal coding sequences, had a microdeletion in the SHOX 3' region. The microdeletion started from a position approximately 200 kb from SHOX coding sequences, and spanned 240-350 kb in physical length involving DXYS233. The results, in conjunction with those reported by Flanagan et al. [2002], suggest that a cis-acting enhancer exists in the SHOX 3' region around DXYS233.- - - - - - - - - - ranking = 1keywords = physical (Clic here for more details about this article) |
10/17. prenatal diagnosis of ring chromosome 6 in a fetus with cerebellar hypoplasia and partial agenesis of corpus callosum: case report and review of the literature.Ring chromosome 6 (RC6) is a rare constitutional abnormality, with variable material loss, leading to a variable clinical phenotype: minimal physical anomalies and mild psychomotor retardation to severe physical and mental defects. Among the 22 published cases, only five have been prenatally detected. We describe here a RC6 prenatally diagnosed. Ultrasound follow-up showed growth retardation and cerebellar hypoplasia. magnetic resonance imaging (MRI) confirmed this, but showed a partial corpus callosum agenesis, leading to amniocentesis and revealing the chromosomal abnormality. Imaging features were correlated with autopsy findings.- - - - - - - - - - ranking = 2keywords = physical (Clic here for more details about this article) |
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