Physical and genetic mapping of the dipeptidase gene DPEP1 to 16q24.3.

We report the subregional physical and genetic mapping on chromosome 16q of a cDNA clone selected as a potential tumor/growth suppressor sequence. By DNA sequencing and RNA expression pattern, this clone was identified as part of the renal dipeptidase gene (DPEP1). Using somatic cell hybrids carrying either different human chromosomes or chromosome 16 segments, we confirm and refine the physical mapping of DPEP1 to the chromosome 16 subregion q24.3. Two RFLPs, a biallelic polymorphism detected by TaqI and a VNTR detected by BamHI, EcoRI, and BglII, are described. Using the VNTR polymorphism, DPEP1 was shown to be linked to D16S7 with a maximum lod score of 5.8 at a recombination fraction of 0.03.

The human placental protein 14 (PP14) gene is localized on chromosome 9q34.

PP14 protein (placental protein 14) is abundantly secreted by the human endometrium under the influence of progesterone. Human PP14 is homologous to beta-lactoglobulin, the main component of equine, bovine, and ovine milk whey. A genomic PP14 probe (PP14G1) was used for the chromosome assignment of the PP14 gene. Somatic hybrid cells enabled PP14G1 to be assigned to chromosome 9. In situ hybridization further refined this assignment to 9q34. The localization of the PP14 gene in the region of the ABO locus is consistent with the linkage described in bovines between beta-lactoglobulin and the J blood group (homologous to the human ABO group).

Isolation of 37 single-copy DNA probes from human chromosome 6 and physical mapping of 11 probes by in situ hybridization.

Fifty-five single-copy DNA probes were isolated from the library LL06NS01, which was constructed from a complete HindIII digest of a flow-sorted human chromosome 6. Because chromosomes from a human x Chinese hamster somatic cell hybrid were used as the starting material for the flow-sorting, the library could be expected to contain some contaminating Chinese hamster DNA as well as DNA from human chromosomes other than 6. Thirty-seven of the 55 probes, however, were shown to map to human chromosome 6 by Southern blot hybridization with DNA from a panel of somatic cell hybrids. Eleven of the probes were mapped further by in situ hybridization. Four probes were localized to the short arm of chromosome 6, six to the long arm, and one to the centromeric region.

Chromosomal assignment of two myosin alkali light-chain genes encoding the ventricular/slow skeletal muscle isoform and the atrial/fetal muscle isoform (MYL3, MYL4).

In all eukaryotes, myosin plays a major role in the maintenance of cell shape and in cellular movement; in association with actin and other contractile proteins it is also a major structural component of the muscle sarcomere. Several isoforms of myosin alkali light chain have been identified, associated with different muscle types. We have recently localized the gene encoding the fast skeletal muscle alkali light-chain isoforms MLC1F and MLC3F (HGM symbol, MYL1) to human chromosome 2q32.1-qter (Cohen-Haguenauer 1988). We present here the chromosomal assignment of two loci encoding the ventricular muscle isoform MLC1V (equivalent to the slow skeletal muscle isoform MLC1Sb) and the atrial muscle isoform MLC1A (equivalent to the fetal isoform MLC1emb) using a panel of 25 independent man-rodent somatic cell hybrids. The MLC1V gene (HGM symbol, MYL3) was mapped to human chromosome 3 using a human full-length cDNA probe that hybridizes to a single major human TaqI2.8-kb fragment. The MLC1A probe (HGM symbol, MYL4) was a 360-bp mouse cDNA fragment that gave a distinct signal with human DNA using low stringency conditions of hybridization and washings and after presaturation of the Southern blots with rodent DNA. A single PstI 7.8-kb fragment gives an intense signal, and its presence correlates with the presence of chromosome 17 among the hybrids. These data are in keeping with the localizations of the MLC1V gene to mouse chromosome 9, and of the MLC1A gene to mouse chromosome 11, which share some markers in common with human chromosomes 3 and 17 respectively.

The human homologues of Fim1, Fim2/c-Fms, and Fim3, three retroviral integration regions involved in mouse myeloblastic leukemias, are respectively located on chromosomes 6p23, 5q33, and 3q27.

Three mouse genomic domains, Fim1, Fim2, and Fim3, were previously described as proviral integration regions frequently involved in the early stages of myeloblastic leukemogenesis induced in vivo or in vitro by the Friend murine leukemia virus. Fim2 was identified as the 5' end of the c-Fms protooncogene, which encodes the receptor of the macrophage colony stimulating factor (Csflr). The functions of Fim1 and Fim3 are not yet known, but these regions are highly conserved among different species. To examine whether these regions could correspond to known human loci involved in genetic alterations specific to some human leukemias, we undertook their chromosomal mapping. The localization of FIM2/c-FMS on 5q33 was confirmed. FIM1 and FIM3 were localized on human chromosomes 6p22.3-p23 and 3q27 respectively. Interestingly, translocations involving these two regions have been described in various hematopoietic malignancies: the t(6;9)(p23;q34) in acute nonlymphocytic leukemias and the 3q26-q28 translocations in a large variety of leukemias.

Regional mapping of the human renin gene to 1q32 by in situ hybridization.

Renin, related to other aspartyl proteases, plays an important role in the cascade which regulates blood pressure and salt metabolism. A human renin 1 100 bp long cDNA including most of the coding region and the 3' non coding region has been subcloned by Soubrier et al., 1983. A 1000 b RNA probe derived by subcloning into pSP64 vector was hybridized to EcoRI and HindIII digests of the DNA of a panel of 24 man-rodent somatic cell hybrids. With HindIII, four restriction fragments were observed, two of them revealing polymorphism (8.4 kb and 6.0 kb). Analysis of the distribution of the human signal among the hybrids confirms the localization of the renin gene (REN) to human chromosome 1. The whole plasmid including the 1 100 bp long insert was used for regional mapping by in situ hybridization; 45% of silver grains were found on chromosome 1, with a clear peak at band 1q32 (33% of silver grains on chromosome 1) and a smaller one at band 1q42 (17%). These data favour a regional localization of the renin gene to 1q32-1q42. Mac Gill et al. (1987) have localized the REN gene to 1q25-1q32 using in situ hybridization. Thus, 1q32 could be the most probable localization. No other peak could be observed. This is in agreement with results obtained with somatic cell hybrids.

The anonymous PAS45 probe detects RFLPs in 13q31.

An anonymous DNA probe PAS45 was isolated. This probe detects an RFLP with two alleles 1 and 2 at the same locus, with the different restriction enzymes (Bg1II, EcoRI, HindIII, PstI, MspI, XbaI). The observed polymorphism is explained by a chromosome rearrangement involving these enzyme cleavage sites. The frequency of alleles 1 and 2 was 0.875 and 0.125, respectively, in a sample of 48 unrelated individuals in France. Codominant inheritance of alleles 1 and 2 was demonstrated in 13 families with 30 offspring. The PAS45 probe was localized on chromosome 13 by somatic cell hybrid analysis and on 13q31 by in situ hybridization. The rearrangement on 13q31 is present in one out of four healthy individuals in France.

cDNA cloning, expression and mapping of human laminin B2 gene to chromosome 1q31.

A laminin B2 chain cDNA clone was isolated from a human lung cDNA library by screening with antibody against mouse laminin. The authenticity of the human cDNA clone was established by comparison of the nucleotide and deduced amino acid sequences of the cDNA insert with those of the previously reported mouse laminin cDNA clones. The human clone (LC7) contained an insert of 0.75 kb (kilobase pair) that corresponded to the last 232 amino acid residues in the carboxyl terminus of the B2 chain. Northern blot analyses with the LC7 probe detected two mRNA transcripts of 8.2 and 5.6 kb in both normal human skin fibroblasts and three human tumor cell lines. The cDNA probe was also used in Southern blot analysis of DNA from human rodent somatic cell hybrids to localize the gene to human chromosome 1. In situ hybridization of the cDNA with metaphase chromosome spreads confirmed the assignment and further mapped the human laminin B2 chain gene to the long arm of chromosome 1 in the band q31.

Characterization of a set of X-linked sequences and of a panel of somatic cell hybrids useful for the regional mapping of the human X chromosome.

We have characterized 19 DNA fragments originating from the human X chromosome. Most of them have been isolated from an X chromosome genomic library (Davies et al. 1981) using a systematic screening procedure. These DNA probes have been used to search for restriction fragment length polymorphisms (RFLP). The frequency of restriction polymorphisms (1 per 350 bp analysed) was lower than expected from data obtained with autosomal fragments. The various probes have been mapped within 12 subchromosomal regions using a panel of human-rodent hybrid cell lines. The validity of the panel was established by hybridization experiments performed with 27 X-specific DNA probes, which yielded information on the relative position of translocation breakpoints on the X chromosome. The DNAs from the various hybrid lines are blotted onto a reusable support which allows one to quickly map any new X-specific DNA fragment. The probes already isolated should be of use to map unbalanced X chromosome aberrations or to characterize new somatic cell hybrid lines. The probes which detect RFLPs define new genetic markers which will help to construct a detailed linkage map of the human X chromosome, and might also serve for the diagnosis of carriers or prenatal diagnosis.

A polymorphic DNA marker linked to cystic fibrosis is located on chromosome 7.

Although cystic fibrosis (CF) is among the most common inherited diseases in Caucasian populations, the basic biochemical defect is not yet known. CF is inherited as an autosomal recessive trait apparently due to mutations in a single gene, whence the efforts made to identify the genetic locus responsible by linkage studies. Two markers have recently been identified that are genetically linked to CF: one is a genetic variation in serum level of activity of the enzyme paraoxonase, and the other is a restriction fragment length polymorphism (RFLP) identified with a randomly isolated DNA probe. We report here that the genetic locus DOCRI-917 defined by the cloned DNA probe is located on chromosome 7.

Assignment of the human coproporphyrinogen oxidase to chromosome 9.

By using somatic cell hybrids between human fibroblasts and hamster or mouse cells, we have assigned the gene for human coproporphyrinogen oxidase to chromosome 9.

Human type I procollagen genes are located on different chromosomes.

A recombinant plasmid containing sequences complementary to human pro-alpha l(I) collagen mRNA was used for the chromosomal assignment of the pro-alpha l(I) collagen gene. Restriction endonuclease analysis of DNA from mouse-human and Chinese hamster-human somatic cell hybrids revealed cosegregation with human chromosome 17. Hybrids containing derivative chromosomes with a t(2;17)(q14;q21) translocation showed cosegregation of the pro-alpha l(I) gene with the segment 17q21 leads to qter. In situ hybridization on human metaphasic chromosomes confirmed this conclusion.

A five-generation family with sacral agenesis and spina bifida: possible similarities with the mouse T-locus.

In man, a malformation that recalls some of the defects associated with T/t mutants in the mouse is sacral agenesis. We report on a family with a high incidence of sacral malformation, ranging from a complete absence of the sacrum (SA), with or without spina bifida aperta, to a spina bifida occulta (SBO) that could only be detected by x-ray. The condition appeared in a man with four children who were all affect, and thereafter, to varying degrees, in 17 of his 28 descendants. Segregation analysis has been performed in this family, using the Elston and Stewart transmission probability model [1971]. The two traits (SA and SBO) were first studied separated and then together. A fully penetrant major dominant gene is show to cause SA. When the phenotypes SA and SBO are considered together, Mendelian transmission is rejected. This could be explained genetically by two alternative hypotheses: genetic heterogeneity or a dominant major gene transmitted in excess by heterozygotes (tau Aa A = 0.896), suggesting a segregation distortion property of an allele at a T-like locus.

Assignment of the human pro alpha 2(I) collagen structural gene (COLIA2) to chromosome 7 by molecular hybridization.

A cDNA for the pro alpha 2 chain of human type I collagen has been recently cloned and amplified. We have used this specific probe to identify the human chromosome carrying the pro alpha 2(I) collagen gene. The DNA from 17 independent human/hamster and human/mouse somatic cell hybrids was digested by Eco RI and the restriction pattern analyzed in Southern blot experiments, using the 32P-labeled cDNA as a hybridization probe. The gene coding for the pro alpha 2 collagen subunit could be unambiguously assigned to human chromosome 7. All the other chromosomes, including chromosome 17, were excluded.