摘要:

SummaryRestriction fragments of the adlolase B gene were studied in 11 patients with hereditary fructose intolerance and compared with the normal pattern. No major deletion of the gene was observed. One patient was found to be a compound heterozygote since one allele with normal restriction sites was inherited from the mother and the other with an abnormal Barn HI site was inherited from the father. The anomaly of the Barn HI fragment observed in this family was not found in 62 normal controls from the same origin as the patient.

ISSN:0003-4800    

DOI:10.1111/j.1469-1809.1984.tb00842.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SummaryThe age distribution of maternal grandmothers of children with Down syndrome was compared with paternal grandparents of the same group and with grandparents of healthy children (controls). The significant advanced maternal grandmaternal age was found in cases of Down syndrome caused by first meiotic error in the maternal oogenesis. The advanced maternal grandmaternal age was found independent of maternal age. No differences were found between the ages of grandfathers of Down syndrome and of controls.

ISSN:0003-4800    

DOI:10.1111/j.1469-1809.1984.tb00843.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SummaryWomen under 25 years at the birth of a child with trisomy 21 (Down syndrome) appear to have an increased risk of having another child with a trisomy. If the risk of recurrence is due solely to an increased production of trisomic conceptions, women with an affected child should have a rate of spontaneous abortion higher than average, since the majority of aneuploid conceptuses are expected to be aborted. We examined fetal loss rates among the other pregnancies of 545 women delivered of a child with trisomy 21 and compared the observed loss rates with those which would be expected were the relative risk for these women for an aneuploidrecognized pregnancythe same as their relative risk for an aneuploid livebirth as reported by others. Overall loss rates in their prior pregnancies were greatest for women who were 20–24 years old at the time of birth of the proband. Moreover, the observed rate of fetal loss for this group of women (33·8%) was at least as high as that predicted from their relative risk for a trisomic livebirth. By contrast, the observed fetal loss rates for women 25–39 years of age at the proband's birth did not differ from the rates predicted on the assumption that their risk for a trisomic recognized pregnancy was not increased, as the livebirth data suggested. The results of this study suggest that women under 25 years at the birth of a child with trisomy 21 have a significantly higher rate of fetal loss in their prior pregnancies than women delivered of the trisomic child at older

ISSN:0003-4800    

DOI:10.1111/j.1469-1809.1984.tb00844.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SummaryData are analysed on livebirths with trisomic syndromes associated with unbalanced Robertsonian translocations born from 1968 to 1981 and reported to the New York State Chromosome Registry. The maternal ages of reported cases were compared with those of the livebirths in the general population who were born in the same year. The number of translocations studied, the mean case‐control differences in years in maternal age (and the standard errors of the mean) were respectively, as follows:D/21 mutants,n= 36. – 0·1 (±0·9); G/21 mutants,n= 46, + 1·5 (±0·8); D/13 mutants,n= 16, + 0·6 (± 1·5); D/21 inherited,n= 12, – 1·0 (± 1·4); G/21 inherited,n= 3, – 0·3 (± 4·4); and D/13 inherited,n= 6, + 2·1 (± 2·4).There was little change in any category if the few cases diagnosed prenatally were included. Only the value for the G/21 mutants is significantly different from zero at the 0·05 level. (The results on G/21 mutants in maternal age are consistent with an earlier Japanese report of an increase of about 2 years over the control values.) The distribution of maternal ages suggests that G/21 mutants may be produced both by maternal age‐independent, and maternal age‐dependent components. The data on D/21 mutants, however, do not indicate the negative association with maternal age reported in Japan. Differences between this study and the Japanese study in analyses of controls may explain this slight variation. But in any event both studies reveal no evidence for an increase in maternal age for unbalanced D/21 mutant or D/21 inherited translocations associated with Down syndrome. This is evidence against the hypothesis that relaxed selection during gestation, after recognition of pregnancy, accounts for the maternal age effects of 47, + 21. In comparison with the results on Robertsonian translocations, the case‐control differences in maternal age in years (and the standard errors of the mean) for 47. + 21 for 2148 livebirths was + 4·6 (± 0·2), and for 2354 cases including those diagnosed prenatally was + 5·3 (± 0·2). The most likely value for an estimated total of 2292 cases of 47, + 21 livebirths that would have been reported in the absence of prenatal diagnosis was + 5·1 (± 0·2). For 47, + 13, for 98 livebirths the mean case‐control difference in maternal age in years was + 1·5 (± 0·7) and for 116 cases including those diagnosed prenatally was + 3·2 (± 0·7). The most likely value for an estimated 108 cases of 47, + 13 in the absence of prenatal diagnosis was + 1·7 (± 0·6). The data on 47, + 13 livebirths confirm suggestive trends from earlier studies at prenatal diagnosis that the maternal age association of this trisomy is weaker than for 47, + 21 or 47, + 18. With regard to paternal age effects, there was no evidence for case‐control differences in paternal age (after controlling on maternal age as well

ISSN:0003-4800    

DOI:10.1111/j.1469-1809.1984.tb00845.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SummaryShermanet at. (1984) concluded from a cytogenetic and genetic analysis of families with the marker (X) syndrome that the rate of the mutation leading to this syndrome is extraordinarily high (7×2 times 10–4in male germ cells), and that these mutations occur exclusively in male germ cells. It is shown by some model calculations that the empirical evidence can be reconciled with more conventional assumptions on the mutation rate if a moderately increased fertility of clinically unaffected female and possibly male carriers in the past is assumed. Indirect evidence for such an increased fertility can be derived from old reports on higher reproduction of slightly subnormal individuals. On the other hand, complete compensation of gene loss in affected individuals by higher fertility of unaffected carriers appears to be rather unlikely. At present, a moderately high mutation rate – as found, for example, in Duchenne muscular dystrophy or haemophilia A – in combination with a moderately increased fertility of clinically unaffected carriers is the most likely alter

ISSN:0003-4800    

DOI:10.1111/j.1469-1809.1984.tb00846.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SummaryAn algorithm is described which attempts to find the maximum likelihood order of the loci on a chromosome using linkage data. It can also use data on locus order if these are available. A computer program which applies this algorithm has been written, and tested on the data for human chromosome 1. The most likely possible order isGDH, PGD, ENO1, Rh, UMPK, Sc, PGM1, AMY, Fy, CAE, 1qh, CMT1, AT3, PEPC.

ISSN:0003-4800    

DOI:10.1111/j.1469-1809.1984.tb00847.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SummaryLod scores are presented from the published and unpublished data of the Galton Laboratory, and from published data on sixteen chromosome 1 loci,AMY, AT3, CAE, CMT1, ELI, ENO1, FUCA, Fy, GDH, PEPC, PGD, PGMI, Rh, Sc, UMPKand1qh.

ISSN:0003-4800    

DOI:10.1111/j.1469-1809.1984.tb00848.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SummaryGenetic epidemiology deals with the interaction of environmental and genetic determinants in common diseases. Linkage analysis is an important branch of this field. The current practice of claiming linkage between two genetic loci when the maximum lod score z(θ) exceeds 3 has not received theoretical justification, whether considered as a sequential or as a fixed sample size test. Within the framework of significance testing, Wald's (1947) formulae are not applicable to allow this procedure a sequential interpretation. Considered as a fixed sample size test, we find that a X2approximation would instead be very adequate. Since repeated significance testing is performed on linkage data, the nominal significance level should be more stringent for each test than the overall level. Some recent developments in group sequential trials by Pocock (1977) and in repeated significance testing by Woodroofe (1979) seem to indicate that the critical value of the maximum lod score should lie roughly between 0·9 and 3·3, depending on the maximum number of repetitions anticipated, on whether the significance level is desired to be 0·05, 0·01 or 0·001, and on whether the test is derived from a one‐sided or a two‐sided consideration. In terms of the group sequential approach, if a maximum of twenty repetitions is allowed, if z(θ)>log10A is considered as a one‐sided test and assumed to be symmetric when linkage is absent, then the type I error is approximately given by 1/A. We also treat the confidence interval approach for exclusion of unlikely recombin

ISSN:0003-4800    

DOI:10.1111/j.1469-1809.1984.tb00849.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

ISSN:0003-4800    

DOI:10.1111/j.1469-1809.1984.tb00850.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Book reviews in this articlesCytogrnetics of the Mammalian X Chromosome. Progress and Topics in Cytogenetics.

ISSN:0003-4800    

DOI:10.1111/j.1469-1809.1984.tb00851.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY