The human gene for the beta subunit of nerve growth factor is located on the proximal short arm of chromosome 1.

Fragments of the recently cloned human gene for the beta subunit of nerve growth factor (beta-NGF) were used as hybridization probes in analyzing two sets of rodent-human somatic cell hybrids for the presence of human beta-NGF sequences. Results from the first set of hybrids assigned the human beta-NGF gene to chromosome 1 and ruled out the presence of sequences of comparable homology on any other chromosome. With the second set of hybrids, which contained seven different, but overlapping, regions of chromosome 1, the NGF locus was mapped to band 1p22.

Human ornithine transcarbamylase locus mapped to band Xp21.1 near the Duchenne muscular dystrophy locus.

The gene for the mitochondrial enzyme ornithine transcarbamylase was mapped to the short arm of the X chromosome by in situ hybridization experiments, with DNA complementary to the human ornithine transcarbamylase gene used as a probe. A series of cell lines with X chromosome abnormalities was used to localize the gene to band Xp21.1. Because the gene maps near the Duchenne muscular dystrophy locus, the ornithine transcarbamylase probe may be useful in carrier detection and prenatal diagnosis of Duchenne muscular dystrophy as well as of ornithine transcarbamylase deficiency.

Oncogene from human EJ bladder carcinoma is located on the short arm of chromosome 11.

The human cellular homolog of the transforming DNA sequence isolated from the bladder carcinoma cell line EJ was localized on the short arm of human chromosome 11 by Southern blot analysis of human-rodent hybrid cell DNA. This locus contains human sequences homologous to the Harvey murine sarcoma virus v-Ha-ras oncogene.

Minute chromosomes replacing the Y chromosome carry Y-specific sequences by restriction fragment analysis and in situ hybridization.

Two unrelated males, a 43-year-old man with azoospermia and a 4-year-old boy with stature at the 10th centile, had similar karyotypes: 46,X,min. The minutes, present in all cells analyzed, stained weakly with G-, C-, and Q-banding methods. To elucidate their origin we used molecular techniques: In HaeIII digests of total genomic DNA from both individuals, no Y-specific reiterated sequences were detected. However, restriction fragment analysis with probe pDP31 demonstrated that the patients' DNA contained the Y-specific fragment. In situ hybridization with the same probe showed that these sequences were present on the minute chromosomes and have not been translocated elsewhere.

Absence of detectable chromosomal and molecular abnormalities in monozygotic twins discordant for the Wiedemann-Beckwith syndrome.

Monozygotic twins discordant for the Wiedemann-Beckwith syndrome (WBS) were studied by cytogenetic and molecular methods to determine if a genetic lesion could be detected in the affected child. Probes known to be localized on the short arm of chromosome 11 and a low copy-repetitive probe were used. No genetic lesions could be ascertained in normal or affected tissue obtained from the WBS twin.

Identification of carriers of Duchenne muscular dystrophy: value of molecular analysis.

Currently, molecular methods are the most accurate diagnostic tools for carrier detection and prenatal diagnosis of Duchenne muscular dystrophy (DMD). This report illustrates the value of molecular diagnosis as opposed to previous diagnostic methods, the need for frequent re-evaluations as new methodologies develop, and the necessity for in-depth genetic counseling. In Family 1, the proposita was predicted to be a carrier by an indirect assay (abnormal in vitro muscle ribosomal protein synthesis). DNA analysis using restriction fragment length polymorphisms (RFLPs) indicated that she was not a carrier. She gave birth to a predicted non-affected male, who inherited the gene in question. In Family 2 the proposita, an obligate carrier, was initially evaluated by RFLP analysis. Two pregnancies were monitored by first trimester chorionic villous sampling. Re-evaluation indicated that all affected individuals, including one of the embryos, carried a deletion of the dystrophin gene. The identification of an RFLP within the region containing the deletion allowed unambiguous determination of the carrier status of all individuals.

[Marfan syndrome and pregnancy. Apropos of 4 cases]. / Syndrome de Marfan et grossesse. A propos de quatre cas.

OBJECTIVES: To create a follow-up protocol for pregnant patients with Marfan syndrome. PATIENTS AND METHODS: We retrospectively reviewed the charts of patients who delivered in the Jeanne de Flandre University Hospital between June 1996 and June 1999. Four pregnant patients with Marfan syndrome were identified. RESULTS: Three of these patients had Bentall procedure. One of them had vaginal delivery and the two others underwent cesarean section. One of these two patients developed aortic valve thrombus at 14 weeks of amenorrhea. The fourth patient did not have surgery and had two vaginal deliveries. DISCUSSION: According to our results and after reviewing literature pregnant patients with Marfan syndrome were divided into two groups. The 1st group was comprised of patients who underwent Bentall procedure. The 2nd one was comprised of patients who did not undergo any surgical procedure. The possibility of vaginal delivery for patients who underwent Bentall procedure (one case) and the interest of Propanolol and anticoagulant treatment are emphasized. CONCLUSION: The multivariant approach of pregnant patients with Marfan syndrome is stressed out with special reference to the potential complications of this syndrome such as aortic dissection and to the problems related to the anticoagulant treatment.

[Prenatal diagnosis of partial trisomy 9p]. / Diagnostic anténatal d'une trisomie 9p partielle.

The prenatal diagnosis of trisomy for the distal half of the short arm of n(o) 9 chromosome (partial trisomy 9p) has been realized from a morphologic ultrasound. A genetic investigation has permitted to establish that this trisomy was due to a bad segregation of a stable translocation present in the patient's mother. To our knowledge, the ultrasound prenatal diagnosis of partial trisomy 9p has never been reported in the literature. The prognosis of this syndrome remains very pejorative and the termination of pregnancy is the most often proposed solution.

[Trisomy 18: ultrasound aspects. Report of 40 cases]. / Trisomie 18: aspects échographiques. A propos de 40 observations.

OBJECTIVE: We describe the different ultrasound findings suggestive of trisomy 18. PATIENTS AND METHODS: We conducted a retrospective study in 40 cases of trisomy 18 diagnosed in the department of obstetrics at the Lille University Hospital between 1988 and 1998. RESULTS: Eighty percent of the women in this series were multiparous. Mean maternal age at discovery of the trisomy as 33.2 years and the mean gestational age was 20.4 weeks. Fifty-five percent of the cases were discovered during the second trimester of pregnancy, 22.5% during the third trimester and 22.5% during the first trimester. One ultrasound abnormality, at least, was detected in 36/40 cases (90%) a percentage that reached 96.8% taking into consideration the ultrasound examinations performed during the second and third trimesters (30/31 cases). The most frequently detected ultrasound abnormalities were: intra uterine growth retardation (IUGR: 50%), poly-hydramnios (42.5%), limb abnormalities (42.5%), cardiac defects (30%), facial abnormalities (37.5%), meningomyelocele (32.5%), digestive abnormalities (32.5%), urinary tract abnormalities (27.5%), lymphangiectasia and cystic hygroma (15%), and single umbilical artery (12.5%). Medical termination of pregnancy (TOP) was performed in 28 cases. There was one spontaneous miscarriage at 8 weeks and one in utero death (IUD) at 39 weeks in a patient who desired to continue her pregnancy. In 6 cases, the issue of the pregnancy was unknown because the patients were lost to follow-up. In 4 cases (10%), pregnancy was continued to delivery of live babies that only survived a few minutes to 7 days. CONCLUSION: The ultrasound signs suggestive of trisomy 18 change according to the term of pregnancy. At the first trimester, most of the signs are nonspecific, such as cystic hydroma or lymphangiectasia, and do not suggest the need for a karyotype. At the end of the second trimester, an association of various signs that alone would not be highly suspect suggest the need for further exploration in search of other signs: early IUGR, associated or not with poly-hydramnios, limb abnormalities, cardiac defects, omphalocele, diaphragmatic hernia, meningomyelocele, enlarged cisterna magna, choroid plexus cysts, single umbilical artery, facial dysmorphism, facial cleft, hydronephrosis.

The c-Ha-ras1, insulin and beta-globin loci map outside the deletion associated with aniridia-Wilms' tumour.

The localization of protooncogenes on human chromosomes may coincide with chromosome breakpoints of consistent translocations in leukaemias or lymphomas, suggesting a direct involvement of oncogenes in carcinogenesis. For example, in Burkitt's lymphoma consistent translocations may be associated with rearrangements of c-myc. Our assignment of the c-Harvey-ras1 oncogene to chromosome 11, precisely to region 11p11 leads to p15 (ref. 5; not 11p13 as stated in ref. 6), has raised the possibility that this oncogene might have a role in the predisposition to nephroblastoma (Wilms' tumour, WT) seen in the aniridia-WT association (AWTA) that is frequently caused by an interstitial deletion of band 11p (ref. 8). We have now studied the organization and copy number of sequences at three loci mapped to 11p: c-Ha-ras1, insulin and gamma-globin in cells from four individuals with structural rearrangements of the short arm of chromosome 11. Our results reported here rule out a close physical linkage between c-Ha-ras1 and the genes responsible for AWTA, and suggest a more distal localization of the beta-globin cluster than currently assumed.

An expressed beta-tubulin gene, TUBB, is located on the short arm of human chromosome 6 and two related sequences are dispersed on chromosomes 8 and 13.

The chromosomal assignments of an expressed beta-tubulin gene and two related sequences have been determined by Southern blot analysis of DNA from a panel of human x Chinese hamster somatic cell hybrids cleaved with Hind III or EcoRI. Probes containing the 3' untranslated regions of the expressed gene M40 and of pseudogene 21 beta were used to localize the M40 sequence (gene symbol TUBB) to chromosome 6 region 6p21----6pter, the 21 beta pseudogene (TUBBP1) to chromosome 8 region 8q21----8pter and a third related sequence (TUBBP2) to chromosome 13. Asynteny of expressed genes and related processed pseudogenes has now been demonstrated for several gene families.

Comparative analysis of mouse-human hybrids with rearranged chromosomes 1 by in situ hybridization and Southern blotting: high-resolution mapping of NRAS, NGFB, and AMY on human chromosome 1.

The human protooncogene NRAS and the genes for the beta-subunit of nerve growth factor (NGFB) and for amylase (AMY) have previously been assigned to the proximal short arm of chromosome 1, but their precise positions have not been unequivocally established. By in situ hybridization of DNA probes for the three genes, we have ascertained the location of complementary sequences in mouse-human somatic cell hybrids that contained translocations of chromosome 1. The results agreed with the presence or absence of the human sequences as determined by Southern blotting of hybrid cell DNA. The in situ data confirmed that the genes were present on the cytologically recognized rearranged chromosome. Compared to the autoradiographic silver grain distribution on normal human chromosome 1, our in situ results obtained with the translocation chromosomes allowed much greater precision of mapping. Both NRAS and NGFB map to band 1p22, and AMY was confirmed in band 1p21.

Chromosomal assignments of three random RFLP loci defined by base-pair changes in MspI sites.

Three cloned single copy sequences isolated from a random partial plasmid library of human EcoRI-HindIII restriction fragments detect MspI site polymorphisms in human DNA. Since at least two of them have allele frequencies that make them suitable for family linkage studies, we have determined their chromosomal localizations. DNA samples extracted from a panel of 31 Chinese hamster x human somatic cell hybrids, that were derived from six different human donors, were analyzed for the presence of human EcoRI or HindIII fragments hybridizing with the three probes. The results were correlated with the human chromosome contents of the hybrids. Concordancy was observed for clone pMS 1-14 (preliminary locus designation DOSLC3) and human chromosome 15, for clone pMS 1-27 (DOSLC2) and chromosome 20, and for clone pMS 1-37 (DOSLC1) and chromosome 3. Two independent hybrids had retained only the long arm of chromosome 3 and did not hybridize with this probe. Therefore, we assign this locus (now termed D3S3) to the short arm of chromosome 3.

DNA analysis of first-trimester chorionic villous biopsies: test for maternal contamination.

We investigated the reliability of chorionic villous biopsy as a method to obtain tissues reflecting the genetic constitution of the embryo. In 12 pregnancies before elective termination, we searched for detectable maternal tissue after careful dissection of villi from small 2-5-mg specimens that yielded 7 micrograms of DNA per mg tissue. In Southern blotting experiments (1-2 micrograms DNA per lane), restriction fragment length polymorphisms (RFLPs) at an autosomal (D14S1) and a sex chromosomal (DXYS1) locus allowed recognition of maternally and embryonically derived alleles. Pure villi were obtained in six of the seven informative cases. One biopsy was not dissected satisfactorily; a mixture of embryonic and maternal DNA was found. Nonvillous tissues were mostly maternally derived in eight informative cases. Sex determination by molecular analysis (alleles at the DXYS1 locus) agreed with the karyotypes of uncultured or cultured villi. In one continuing pregnancy, distinct RFLPs indicated maternal inheritance of the alpha-thalassemia 1 trait in a female embryo without detectable maternal contamination. Reliable prenatal diagnosis depends on the specimen's purity. Maternal contamination can be evaluated by DNA analyses.

Amplified DNA in Y1 mouse adrenal tumor cells: isolation of cDNAs complementary to an amplified c-Ki-ras gene and localization of homologous sequences to mouse chromosome 6.

We have isolated cDNA clones complementary to a c-Ki-ras cellular oncogene that is amplified in Y1 mouse adrenal tumor cells, with the amplified sequences located on double-minute chromatin bodies (DMs) and homogeneously staining chromosomal regions (HSRs). Characterization of the cDNAs included the isolation of corresponding genomic clones, Northern blot analysis of RNA, and DNA sequence analysis. Our studies demonstrate that the c-Ki-ras gene amplified in the Y1 cells is homologous to the human c-Ki-ras2 gene. We have also obtained evidence that, in addition to c-Ki-ras, at least one other transcription unit has been amplified in the mouse adrenal tumor cells. Moreover, by Southern blot analysis of Chinese hamster-mouse somatic cell hybrids, we have determined that the amplified DNA sequences associated with DMs and HSRs, including the c-Ki-ras gene, are present in normal mouse cells on chromosome 6.

Gene mapping in Alport families with different basement membrane antigenic phenotypes.

The present study was undertaken to determine whether differences among Alport kindreds in the antigenic phenotypes of their basement membranes result from defects at distinct genetic loci or from allelic mutations at a single locus. We analyzed linkage of the Alport gene to polymorphic loci on the X chromosome in three families with Alport syndrome. In two of the families, epidermal basement membranes of affected members showed altered immunohistologic reactivity with a discriminating antibody (FNS1) that identified a 26 kD peptide in the NCl domain of basement membrane collagen. In the third family epidermal basement membranes of affected individuals reacted normally with the antibody. The disease gene mapped to the Xq21-q22 region of the long arm of the X chromosome in the two families with altered basement membrane antigenicity and in the family with normal basement membrane antigens. We conclude that Alport syndrome in each of these kindreds arose from allelic mutations at a single genetic locus, although we cannot at this time exclude the possibility that two or more tightly linked genes are involved. As the genes for the known chains of type IV collagen are on chromosome 13, our findings suggest that the Alport gene may encode a new basement membrane collagen chain.

Comparative gene mapping: murine lambda light chain genes are located in region cen to B5 of mouse chromosome 16 not homologous to human chromosome 21.

We have mapped the genes for murine immunoglobulin lambda light chains to the region of chromosome 16 proximal to band B5 by hybridizing a cDNA probe for gamma light chains to the DNA of a series of hybrid clones made between mouse fibroblasts carrying Searle's translocation, T(X;16)16H, and Chinese hamster cells. Based on homology, we predict that the human Ig gamma gene (IGL) will map to the proximal two-thirds of HSA 22.