摘要:

Symptomatic alpha-thalassemia (α-thal) as found in South-East Asia is uncommon in India. However, the presence of Hb Bart’s in cord blood samples has been reported from different parts of India and the prevalence of α-thal has ranged from 0.5 to 18% by different electrophoretic techniques. The methodology utilised has ranged from paper electrophoresis to isoelectric focussing (IEF). We screened 798 cord bloods for the presence of Hb Bart’s by cellulose acetate electrophoresis and found a prevalence rate of α-thal of 15.3% in a heterogenous population in Bombay. A comparison of four different electrophoretic techniques for detection of Hb Bart’s in 138 neonates showed that cellulose acetate and starch gel electrophoresis were by and large comparable and only a little less sensitive than IEF. Paper electrophoresis used at many centers in India was most insensitive. As α-genotyping is not possible at most centers in the country, it is suggested that a simple cellulose acetate electrophoresis would be the method of choice for screening neonates for α-thal in India. As a part of our follow-up study, α-genotyping was done by Southern blot hybridization in 24 cases who had shown variable levels of Hb Bart’s at birth. The rightward deletion (-α3.7/) either in a heterozygous or homozygous condition was the only gene defect encountered in this preliminary study. However, 7 of 24 cases (29.17%) showed no correlation between Hb Bart’s level

ISSN:0001-5652    

DOI:10.1159/000154410

出版商:S. Karger AG    

年代:1997

数据来源: Karger

摘要:

Interferon-α (IFN-α) is a protein family controlled by altogether 26 different IFN-α genes. We have previously described an SspI polymorphism in the IFN A17 gene and an association between the SspI A2 allele and nasopharyngeal cancer. In this paper we present data on ethnic differences with respect to IFN A17 SspI allele frequencies. Thus the frequency of the SspI A1 allele was high in two different Chinese populations (51 and 48%, respectively) and much lower (11%) in Swedes. Intermediate values were found in African Blacks (32%), Indians (25%), Saamis (29%) and Finns (24%). The very pronounced differences between major ethnic groups make the IFN A17 SspI polymorphism a very informative anthropological marker system and suggest that it may be balanced and maintained by natural selecti

ISSN:0001-5652    

DOI:10.1159/000154411

出版商:S. Karger AG    

年代:1997

数据来源: Karger

摘要:

20 microsatellite polymorphisms: HUMHPRT, HUMD3S1358, HUMTH01, HUMACPP, HUMVWF, HUMD16S310, HUMD4S243, HUMTPO, HUMFES/FPS, HUMF13A1, HUMDHFRP2, HUMD11S2010, HUMD13S767, HUMD9S926, HUMD2S1328, HUMD14S306, HUMD18S848, HUMD5S818, HUMD7S820 and HUMFGA were analyzed in a worldwide survey covering five continents and allele frequencies are given. There is a high heterogeneity in allele frequencies among continents. A neighbor-joining tree based on Fst distance shows a pattern of differentiation that may reflect the role of drift in the development of genetic differences among humans. The variation found between continents confirms the usefulness of tetranucleotide microsatellites in human genetic variation studies.

ISSN:0001-5652    

DOI:10.1159/000154412

出版商:S. Karger AG    

年代:1997

数据来源: Karger

摘要:

There are two basic algorithms for calculating multipoint linkage likelihoods: in one the computational effort increases linearly with the number of pedigree members and exponentially with the number of markers, in the other the effort increases exponentially with the number of persons but linearly with the number of markers. We describe a faster version of the latter algorithm for which there is no penalty in making the recombination fraction meiosis specific. This can lead to faster and potentially more powerful linkage analysis whenever the number of nonfounder meioses in a pedigree is not too large.

ISSN:0001-5652    

DOI:10.1159/000154413

出版商:S. Karger AG    

年代:1997

数据来源: Karger

摘要:

The allelic distribution of the polymorphic serum proteins AHSG, PLG, FXIIIB and HP was studied in six Jewish groups who migrated to Israel from the Middle East, North Africa, Rumania, Bulgaria, Central and Eastern Europe. The observed AHSG and PLG allele frequencies in these Jewish groups were more or less similar to the observed distributions in non-Jewish populations from their respective areas of origin, while FXIIIB and HP frequencies were similar to those in European populations. Therefore, no uniform pattern of genetic relationships between the Jewish groups was observed. A genetic distance analysis including comparative data from Europe and the Middle East reflected differences between the Jewish groups according to their areas of origin.

ISSN:0001-5652    

DOI:10.1159/000154414

出版商:S. Karger AG    

年代:1997

数据来源: Karger

摘要:

We have developed software and statistical tools for linkage analysis of polygenic diseases. We use type I diabetes mellitus (insulin-dependent diabetes mellitus, IDDM) as our model system. Two susceptibility loci (IDDM1 on 6p21 and IDDM2 on 11 p15) are well established, and recent genome searches suggest the existence of other susceptibility loci. We have implemented CASPAR, a software tool that makes it possible to test for linkage quickly and efficiently using multiple polymorphic DNA markers simultaneously in nuclear families consisting of two unaffected parents and a pair of affected siblings (ASP). We use a simulation-based method to determine whether lod scores from a collection of ASP tests are significant. We test our new software and statistical tools to assess linkage of IDDM5 and IDDM1 conditioned on analyses with 1 or 2 other unlinked type I diabetes susceptibility loci. The results from the CASPAR analysis suggest that conditioning of IDDM5 on IDDM1 and IDDM4, and of IDDM7 on IDDM1 and IDDM1 provides significant benefits for the genetic analysis of polygenic loci.

ISSN:0001-5652    

DOI:10.1159/000154415

出版商:S. Karger AG    

年代:1997

数据来源: Karger

摘要:

The admixture test (A-test) is a popular method for the analysis of linkage data when locus heterogeneity is suspected. It can be applied on pairwise linkage data, multipoint data and even for the simultaneous analysis of data from multiple dispersed candidate regions. However, very little is known about the conditions for the use of the method under these divergent circumstances. By performing analytical evaluations, we demonstrate that the A-test is inconsistent if there is a relationship between the phenotype and the probability of being linked. Biased estimates of the recombination fraction (θ) and the proportion of linked families (α) may occur if the actual frequency of linked families is not identical among small and large families. We conclude that the A-test should be used with caution if the phenotype and the probability of developing the phenotype at a certain age cannot be shown to be equal for family members of linked and unlinked families. If dissimilarities in family size cannot be ruled out, the extent of bias should be considered and size specific α-values should be used in risk calculation

ISSN:0001-5652    

DOI:10.1159/000154416

出版商:S. Karger AG    

年代:1997

数据来源: Karger

ISSN:0001-5652    

DOI:10.1159/000154417

出版商:S. Karger AG    

年代:1997

数据来源: Karger

ISSN:0001-5652    

DOI:10.1159/000154418

出版商:S. Karger AG    

年代:1997

数据来源: Karger