Human chromosome 16 conservation in primates

A study was made of the organization of the chromosome orthologous to HSA16 in primates using a panel of 8 BAC probes spanning human chromosome 16. The probes were used in FISH experiments on great apes and on representatives of the Old World monkeys, New World monkeys, and lemurs. The domestic cat was used as an outgroup. The results indicate that 16p and 16q were separate chromosomes in a primate ancestor. They fused in a Catarrhini ancestor giving rise to the present day form found in HSA, great apes, and Old World monkeys. Several rearrangements were found in New World monkeys.     

45X/46X,r(X) with syndactyly and severe mental retardation

Two white females, age 2 1/2 and 33 years, respectively, were investigated because of severe mental retardation associated with neurologic abnormalities, coarse face, and soft tissue syndactyly involving upper and lower limbs. Each had cytogenetic findings of a mosaic variant of Ullrich-Turner syndrome with X ring chromosome in peripheral lymphocyte and skin fibroblasts. Early X replication occurred in one-third of the X ring chromosomes; there was no evidence for X-autosome translocation involving either X and an autosomal duplication; results of studies for fragility of the X chromosomes were unremarkable. In situ hybridization with an X centromere probe was positive for the ring. To our knowledge, the unusual constellation of cytogenetic, physical, and mental findings seen in these 2 individuals has not been reported previously.     

Electronic data processing in the Danish Cytogenetic Central Register and EDP problems of registers in general

A brief introduction to the Danish Cytogenetic Central Register (DCCR) is given, and possibilities, principles and problems concerning the establishment and maintenance of a national cytogenetic register are presented.
Various data carrier media for registers in general are discussed, of which the magnetic disc is considered most appropriate. General principles for programs capable of performing insertions, deletions and other modifications in the data base are outlined as well as the principles for the programs in the DCCR.
The individual records should preferably be identified by aid of a central person registration number (CPR) rather than by name. The data should be stored and sorted by this identification in order to facilitate retrieval of a desired record. The structure of the records is discussed with regard to prevention of the occurrence of certain errors as well as the optimization of processing.
Flexibility and economy of space are achieved by using programs able to handle records of unequal length, and problems occurring in connection with this are discussed. The question of how to protect sensitive data is dealt with, and two different methods used in the DCCR are outlined. Programs capable of analyzing karyotypes with the purpose of recognizing various cytogenetic syndromes have been developed for use in the DCCR. Various examples of computing times of typical program runs are presented.     

血清抗果蝇唾腺染色体抗体测定及临床意义探讨

以果蝇唾腺作为基质,用间接免疫荧光法检测血清抗果蝇唾腺染色体抗体[简称抗染色体抗体(Anti—chromosome antibody AchrA)]。正常人及其它风湿性疾病患者共151例,均为阴性,而系统性红斑狼疮(SLE)患者44例,AchrA阳性者占16例(36.4%)。揭示AchrA对SLE有高度特异性及一定的敏感性。对比SLE患者的AchrA及抗核抗体(ANA),双阳性占15例(34.1%),提示与两种抗体起反应的核成分不尽相同。     

Melosis in holocentric chromosomes: Kinetic activity is randomly restricted to the chromatid ends of sex univalents inGraphosoma italicum (Heteroptera)

We have determined the number and location of the nucleolar organizing regions in spermatocytes ofGraphosoma italicum (2n=12A+ XY/XX) by means of silver impregnation, chromomycin A₃/distamycin A staining and fluorescencein situ hybridization. The identification of only one nucleolar organizing region located at one of the X chromosome ends has provided a suitable cytological marker to analyse the segregation of this univalent and that of the XY pseudobivalent during the first and second meiotic divisions respectively. Our results clearly show that at first meiotic metaphase the chromatids of the X chromosome are orientated with their long axes perpendicular to the polar axis. Although the kinetic activity is restricted to only one end in both X chromatids during the first meiotic division, both ends of the same chromatid have the same probability of showing such kinetic activity. In this sense, we also report that the chromatid segregation maybe initiated either at the same sister chromatid ends or at opposite ends in each chromatid. Thus, this indicates a sex chromatid independence as regards to the chromatid segregation during the first meiotic division. Throughout the second meiotic division both ends of the X chromatid are involved with the same probability in the end-to-end association to conform the XY pseudobivalent. This also implies a random localization of the kinetic activity at the ends opposite to those involved in the end-to-end association.accepted for publication by J. S. (Pat) Heslop-Harrison     

Complex evolution of X and Y autosomal translocations in the giant mole-rat, Cryptomys mechowi (Bathyergidae)

Cross-species chromosome painting was used to determine homologous chromosomal regions between two species of mole-rat, the naked mole-rat, Heterocephalus glaber (2n = 60), and the giant mole-rat, Cryptomys mechowi (2n = 40), using flow-sorted painting probes representative of all but two of the H. glaber chromosomal complement. In total 43 homologous regions were identified in the C. mechowi genome. Eight H. glaber chromosomes are retained in toto in C. mechowi, and 13 produce two or more signals in this species. The most striking difference in the karyotypes of the two taxa concerns their sex chromosomes. The H. glaber painting probes identified a complex series of translocations that involved the fractionation of four autosomes and the subsequent translocation of segments to the sex chromosomes and to autosomal partners in the C. mechowi genome. An intercalary heterochromatic block (IHB) was detected in sex chromosomes of C. mechowi at the boundary with the translocated autosomal segment. We discuss the likely sequence of evolutionary events that has led to the contemporary composition of the C. mechowi sex chromosomes, and consider these in the light of prevailing views on the genesis of sex chromosomes in mammals.     

No Association between SNP rs498055 on Chromosome 10 and Late-Onset Alzheimer Disease in Multiple Datasets

SNP rs498055 in the predicted gene LOC439999 on chromosome 10 was recently identified as being strongly associated with late-onset Alzheimer disease (LOAD). This SNP falls within a chromosomal region that has engendered continued interest generated from both preliminary genetic linkage and candidate gene studies. To independently evaluate this interesting candidate SNP we examined four independent datasets, three family-based and one case-control. All the cases were late-onset AD Caucasian patients with minimum age at onset ≥ 60 years. None of the three family samples or the combined family-based dataset showed association in either allelic or genotypic family-based association tests at p < 0.05. Both original and OSA two-point LOD scores were calculated. However, there was no evidence indicating linkage no matter what covariates were applied (the highest LOD score was 0.82). The case-control dataset did not demonstrate any association between this SNP and AD (all p-values > 0.52). Our results do not confirm the previous association, but are consistent with a more recent negative association result that used family-based association tests to examine the effect of this SNP in two family datasets. Thus we conclude that rs498055 is not associated with an increased risk of LOAD.     

Sex chromosome mosaicism in couples undergoing intracytoplasmic sperm injection

BACKGROUND: Several studies have shown an increased frequency of constitutional chromosome aberrations in male and female partners of couples examined prior to ICSI. We conducted a cohort study to determine whether there was an increase in numerical sex chromosome mosaicism among couples undergoing ICSI compared with fertile couples. METHODS: Cytogenetic investigations were performed in 228 females and 208 males seen for ICSI between January 1997 and March 2001. They were matched to control females and males. RESULTS: Sex chromosome loss or gain was observed in at least one cell from 24.1% of ICSI women in comparison with 22% of controls (not significant). A significant difference between these two groups was found when X chromosome loss in at least two cells was considered, 9.6% for ICSI females versus 4.8% for controls (P = 0.01). No significant difference was observed between male groups concerning loss or gain of the X or Y chromosome. CONCLUSION: Our results support previously published studies indicating that the loss of an X chromosome in a single cell in females undergoing ICSI is probably an artefact. However, they suggest that a woman could have true sex chromosome mosaicism when two 45,X0 cells are found.