A new AAT allele (PI Zbristol) has been discovered in a woman with an obstetric history of three perinatal deaths from fulminant liver disease and no living offspring. She and her father were both PI M1Zbristol heterozygotes. The Zbristol protein is active as a proteinase inhibitor but appeared to be deficient in the plasma to about the same degree as the S protein in MS heterozygotes. It focuses on the basic side of Z and lacks the normal pattern of secondary isoforms associated with the commonly occurring AAT variants and migrates faster than normal on an SDS electrophoresis gel. The Zbristol mutation was found to be a C to T transition at codon 85 changing ACG (Thr) to ATG (Met). This disrupts the N-glycosylation site starting at Asn 83 preventing glycosylation at residue 83 in the PI Zbristol protein and explains the protein isoelectric focusing and SDS gel electrophoresis results. An analysis of haplotypes in the propositus and her father indicated that the Zbristol mutation occurred on the common M1(Val 213) genetic background. The new mutation also led to the generation of an NlaIII restriction endonuclease recognition site. Cell lines from two offspring tested for the presence of this NlaIII site revealed that one had the variant and the other did not. Thus, the relationship between Zbristol and fulminant liver disease in the offspring is unclear.

The caudal-type homeobox gene Cdx2 encodes a transcription factor which is expressed in the intestine and is thought to play an important role in the proliferation and differentiation of intestinal epithelial cells. Mice heterozygous for null mutations in the caudal-type homeobox gene Cdx2 show multiple adenomatous polyps in the proximal colon in addition to skeletal problems associated with abnormal segmentation. In human colorectal cancer the expression of both CDX2 and carbonic anhydrase 1, a gene regulated by CDX2, is reduced or absent. It is possible that mutation of CDX2 is a primary event in the origin of some colorectal cancers. We have cloned human CDX2 cDNA and report here the nucleotide and protein sequences and assignment of the human gene to chromosome 13q12–13.

The transcription map of the human genome published by Schuler et al. (1996) is a valuable resource in which approximately one quarter of all human genes have been mapped with respect to genetic framework markers using radiation hybrids. We have taken information from this map to provide potential genes within the TSC1 candidate region on chromosome 9q34. In so doing we have been able to provide an independent assay of the quality of the radiation hybrid mapping by using somatic cell hybrids and a 2 Mb cosmid contig covering the TSC1 region as mapping tools. In addition, we have built sequence contigs of ESTs for 25 clusters. This has shown that about 20% of the relevant EST clusters in the Unigene resource (Boguski & Schuler 1995) contain chimaeric clones.

Earlier analysis of the Italian population showed patterns of genetic differentiation that were interpreted as being the result of population settlements going back to pre-Roman times. DNA disease mutations may be a powerful tool in further testing this hypothesis since the analysis of diseased individuals can detect variants too rare to be resolved in normal individuals. We present data on the relative frequencies of 60 cystic fibrosis (CF) mutations in Italy and the geographical distribution of the 12 most frequent CF mutations screened in 3492 CF chromosomes originating in 13 Italian regions. The 12 most frequent mutations characterize about 73% of the Italian CF chromosomes. The most common mutation, ΔF508, has an average frequency of 51%, followed by N1303K and G542X, both with average frequencies around 5%. Multivariate analyses show that the relative frequencies of CF mutations are heterogeneous among Italian regions, and that this heterogeneity is weakly correlated with the geographical pattern of non-DNA ‘classical’ genetic markers. The northern regions are well differentiated from the central-southern regions and within the former group the western and eastern regions are remarkably distinct. Moreover, Sardinia shows the presence of mutation T338I, which seems absent in any other European CF chromosome. The north-western regions of Italy, characterized by the mutation 1717-1G→A, were under Celtic influence, while the north-east regions, characterized by the mutations R1162X, 2183AA→G and 711­5G→A, were under the influence of the Venetic culture.

The polymorphisms of nine loci containing reiterated CAG repeats were examined in four populations from three continents. Their normal variation was analysed across populations or in subsets of loci grouped according to either the presence/absence of disease-associated expansions or CAG interruptions. A unifying feature of the allele distributions of all loci in all populations was the marked non-normality. Significantly larger numbers of alleles, average lengths, length ranges and variances in repeat number were observed in loci with vs. without known expansions. Significantly longer alleles were found at loci with vs. without interruption of the (CAG)n motif. The nine loci detected levels of inter-population variability comparable to other loci. Altogether the data are at odds with a model assuming that autosomal expressed trinucleotides accumulate variation exclusively by insertion/deletion of a single unit.

We defined the Y-chromosome haplotypes on the basis of six polymorphic sites: an Alu-element insertion (YAP), a single-base change (C→T at DYS199), one trinucleotide repeat (DYS392) and three tetranucleotide repeats (DYS393, DYS390 and DYS19). Among 140 Y chromosomes from Whites, Blacks, Japanese and Amerindians we identified 67 different haplotypes, the majority of them population-specific; only seven haplotypes were shared by three different racial groups, mostly owing to admixture. Overall, three main lineages can be defined on the basis of the YAP/DYS199/DYS392 markers: (a) a predominant /−/C/10/13/22 (or) 23/ lineage, observed among all racial groups; (b) a/+/C/ lineage which predominates among Blacks (comprising mainly the sublineage /+/C/10/13/), although it is eventually found among Japanese and Whites; and (c) a /−/T/ lineage observed only among Amerindians (comprising mainly the sublineage /−/T/13/13/). The decreasing haplotype diversity of the three lineages agrees with the idea that the first is the most ancient, while the last is the more recent. The data also indicate that the YAP insertion occurred in a /−/C/10/13/ chromosome and the C→T mutation occurred in a /−/C/13/13/ chromosome. Finally, the data suggest that at least two Y-chromosome lineages (/−/C/13/ and /−/T/13/) contributed to the early peopling of the Americas, and supports the hypothesis that /−/T/13/ could be derived from /−/C/13/ and that both haplotypes could be present in the ancestral populations that peopled the continent.

LCN1 gene encodes the tear lipocalin; the lipocalins are a large and growing family of proteins characterized by their ability to bind small hydrophobic molecules. We report here the location of a dinucleotide repeat microsatellite marker (D9S1826) close to LCN1 gene. Using the CEPH reference families, the position of LCN1 is located within the 9q34 genetic map between D9S23 and D9S158.

The chromosomal location of the human fast skeletal muscle troponin C (TNNC2) gene was determined using somatic cell hybrids. PCR-based analysis of a ‘monochromosomal’ hybrid panel identified the presence of the TNNC2 gene on human chromosome 20 and subsequent analysis of the Genebridge4 radiation hybrid panel located the gene between D20S721 and GCT10F11 with a lod score of >3.