Genetic mapping of Xp22.12-p22.31, with a refined localization for spondyloepiphyseal dysplasia (SEDL).

Spondyloepiphyseal dysplasia tarda (SEDL) is an X-linked recessive disorder characterized in affected males by short stature resulting from a growth defect of the vertebral bodies. We have extended our earlier studies by analyzing 15 families with newly identified microsatellite DNA markers; analysis of recombination events with these markers indicates that the gene responsible for SEDL is located in Xp22 between DXS 16 and DXS 987 on an interval spanning approximately 2 Mb.

The gene for Bazex-Dupré-Christol syndrome maps to chromosome Xq.

Bazex-Dupré-Christol syndrome is an inherited condition with skin cancer predisposition characterized by follicular atrophoderma, hypotrichosis, and early onset of multiple basal cell carcinomas. Previous reports suggested an X-linked mode of inheritance. We therefore performed linkage analysis with microsatellite markers of the X chromosome in three families.

Fine deletion mapping of the p22 region of the human X chromosome using a radiation-induced hybrid panel.

Radiation-induced somatic cell hybrids containing fragments of the human X chromosome were constructed. A panel of 17 hybrids was selected with the help of known markers in the Xp22 region. These hybrids identified 11 different breakpoints between Xp22.

Localization of a new type of X-linked liver glycogenosis to the chromosomal region Xp22 containing the liver alpha-subunit of phosphorylase kinase (PHKA2).

We describe here a new type of X-linked liver glycogen storage disease. The main symptoms include liver enlargement and growth retardation. The clinical and biochemical abnormalities of this glycogenosis are similar to those of classical X-linked liver glycogenosis due to phosphorylase kinase deficiency (XLG).

Deletions in the COL4A5 collagen gene in X-linked Alport syndrome. Characterization of the pathological transcripts in nonrenal cells and correlation with disease expression.

The type IV collagen alpha 5 chain (COL4A5) gene of 88 unrelated male patients with X-linked Alport syndrome was tested for major gene rearrangements by Southern blot analysis, using COL4A5 cDNA probes. 14 different deletions were detected, providing a 16% deletion rate in the COL4A5 gene in the patient population. The deletions are dispersed all over the gene with different sizes, ranging from 1 kb to the complete absence of the gene (> 250 kb) in one patient.

Rearrangements between irradiated chromosomes in three-species radiation hybrid cell lines revealed by two-color in situ hybridization.

A human-hamster hybrid cell line containing only the human X chromosome (GM06318B) was exposed to 6,000-7,000 rad of X-rays and fused with a mouse cell line (CL1D,TK-). Three radiation hybrids, LXKC40, LXKC50, and LXKC56, were selected among 39 independent clones containing human material. Two-color in situ hybridization with total genomic DNA probes (cot1 human DNA and hamster total genomic DNA) was used to analyse the irradiated chromosome rearrangements.

An irradiation-reduced hybrid panel for fine-structure mapping of the Xq28 region in the human genome.

Irradiation-reduced somatic cell hybrids containing fragments of the human X chromosome were constructed. Analysis of 16 hybrids that retained the Xq28 region with 12 Xq28-specific markers identified at least six different breakpoints, supporting the order cen-DXS304-DXS374-(DXS33, DXS134, DXS52, DXS15)-RCP-(DXS254, G6PD, F8C)-(DXS115, DXYS64)-qter. The generated panel of hybrids provides a useful tool for fine mapping of probes in the Xq28 region.

Isolation and characterisation of five new anonymous X-specific probes. One of them detecting a TaqI RFLP.

The authors isolated five single-copy X-specific probes from an X-enriched library. These probes were regionally localized on the X chromosome by using somatic hybrid cell lines obtained from patients carrying different X-autosome translocations. Three clones were located between Xq23 and Xq26, the two others were mapped between Xp21 and Xp11.

Alport syndrome and diffuse leiomyomatosis: deletions in the 5' end of the COL4A5 collagen gene.

Alport syndrome (AS) is an hereditary glomerulonephritis that is mainly inherited as a dominant X-linked trait. Structural abnormalities in the type IV collagen alpha 5 chain gene (COL4A5), which maps to Xq22, have recently been detected in several patients with AS. The association of AS with diffuse esophageal leiomyomatosis (DL) has been reported in 24 patients, most of them also suffering from congenital cataract.

Isolation of new probes from Xq12-->q13: an example of the screening of reference libraries with Alu-PCR products from radiation hybrids.

In order to isolate new probes from the juxtacentromeric region of the long arm of the human X chromosome, we used Alu-mediated polymerase chain reaction (Alu-PCR) products as probes to directly screen a chromosome X-specific gridded cosmid library. These Alu-PCR products were synthesized from radiation hybrids containing the loci DXS159, PGK1, and PGK1P1. This approach allowed us to select 18 cosmids capable of hybridizing with at least two Alu-PCR products.

Mapping of human chromosome 22 with a panel of somatic cell hybrids.

The adenylosuccinate lyase (ADSL) which is essential for generating adenylate, maps to the long arm of chromosome 22. By using a Chinese hamster ovary cell line deficient in ADSL activity, we have constructed a set of 17 somatic cell hybrids containing defined regions of human chromosome 22. This panel was extended with six additional hybrids, obtained in other laboratories using various methods of selection.

New polymorphism and a new chromosome breakpoint establish the physical and genetic mapping of DXS369 in the DXS98-FRAXA interval.

Recently some of us cloned a new probe RN1 (DXS369), which appears a close marker for the fragile X locus (FRAXA) [Oostra et al.: Genomics 1990]. We present here new evidence for its physical and genetic mapping in the DXS98--FRAXA interval.

A new DNA marker tightly linked to the fragile X locus (FRAXA).

The fragile X syndrome is the most common cause of familial mental retardation. Genetic counseling and gene isolation are hampered by a lack of DNA markers close to the disease locus. Two somatic cell hybrids that each contain a human X chromosome with a breakpoint close to the fragile X locus have been characterized.

The gene for incontinentia pigmenti is assigned to Xq28.

A linkage study of eight families with incontinentia pigmenti (IP) has been performed, and linkage to site DXS52 has been established. We suggest that the IP locus lies in the Xq terminal region on the long arm of the X chromosome.

Incontinentia pigmenti: Xp breakpoint is not the same in a case of r(X) and in X/autosome translocations.

X-specific DNA probes were used to characterize the r(X) of a 45,X/46,X,r(X) female patient with Incontinentia pigmenti. It was found to be of maternal origin. Breakpoints were shown to be in or distal to p11.

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.

Spondyloepiphyseal dysplasia tarda: linkage with genetic markers from the distal short arm of the X chromosome.

A linkage study of six families with spondyloepiphyseal dysplasia tarda (SEDL) has been performed. A linkage to site DXS41 (theta = 0.08; z = 3.

Linkage studies in X-linked Alport's syndrome.

Four kindreds segregating for Alport's syndrome (ASLN) compatible with a X-linked inheritance were studied for linkage with polymorphic markers of the human X chromosome. No recombinant was observed between the ASLN locus and the DXS101 and DXS94 loci, the maximum lod scores were z = 3.93 and 3.

Time dependence of X gene reactivation induced by 5-azacytidine: possible progressive restructuring of chromatin.

According to the theoretical mechanism of DNA demethylation by 5-azacytidine, the complete demethylation of one site will require two cell divisions. If reexpression is directly related to demethylation, a maximal reexpression is expected after two cell divisions. In a hamster X human hybrid cell line containing an inactive human X chromosome treated by 5-azacytidine, we show that HPRT reactivation frequency is increased more than 10-fold when cells are allowed to divide 14 times before the selection for the HPRT reactivants.

Mapping of the gene for anti-müllerian hormone to the short arm of human chromosome 19.

The gene coding for human anti-Müllerian hormone (AMH) was localized to subbands p13.2----p13.3 on chromosome 19, using in situ hybridization and Southern blot analysis of a panel of man-mouse and man-hamster somatic cell hybrids.

Inactive X chromosome gene reactivation induced by 5-azacytidine, is not correlated with the modification of the pattern of replication.

The replication pattern of a human inactive X chromosome reactivated for one to four genes by 5-azacytidine has been studied by the BrdU-33258-Hoechst-Giemsa technique in four subclones of a somatic hamster-human hybrid. In one of them the pattern was clearly modified. In the three others the changes were not significant.

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.

Gene for apolipoprotein CII is on human chromosome 19.

We have used a cloned cDNA probe for human apolipoprotein CII (apo CII) and Southern blotting techniques to identify the human apo CII gene in DNA from a series of rodent X human somatic cell hybrids. Our results provide evidence for the assignment of this gene to human chromosome 19.