Additional polymorphism for D7S8 linked to cystic fibrosis including detection by DNA amplification.
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Chromosomes, Human, Pair 7↗
Biomedical subjects
H Northrup
Publications and source records attributed to H Northrup.
Multilocus linkage analysis with the human argininosuccinate synthetase gene.
We have identified three restriction fragment length polymorphisms (RFLPs) from within the argininosuccinate synthetase (ASS) gene which maps to human chromosome 9q34-qter. Although RFLPs at pseudogene loci are detected by the cDNA, these are the first polymorphisms reported at the ASS locus. The three RFLPs are in linkage equilibrium with each other, and haplotypes for the ASS locus are highly informative. Two-locus recombination estimates between ASS and seven other 9q markers indicated that ASS is closest to the ABO blood group with a recombination fraction of 0.04 (0.005-0.11). A multilocus lod score analysis with these seven 9q markers indicated that ASS maps between ABL and MCT136 close to ABO, but it is uncertain if ASS is centromeric or telomeric to ABO.
Alleles↗
Prenatal detection of 46,XY,rec(5),dup q, inv(5)(p13q33) using DNA analysis, flow cytometry, and in situ hybridization to supplement classical cytogenetic analysis.
Distinguishing between balanced and unbalanced chromosome complements segregating from parental rearrangements may be difficult using only classical cytogenetic techniques if banding morphology is similar under both expectations. In these situations, supplementing cytogenetic analysis with molecular genetic techniques and flow cytometry may provide increased diagnostic accuracy. To illustrate this, we present a case in which similar band pattern morphology would be expected for both the balanced carrier (heterozygote) and the recombinant dup q chromosome complements segregating from a mother with a balanced inversion [46,XX,inv(5)(p13q33)]. The parents came to Northwestern for consultation after receiving conflicting interpretations of their first amniotic fluid cultures. An ultrasound examination was said to be normal. They inquired whether there were ways to increase their confidence that the complement was unbalanced. Their reluctance to terminate the pregnancy was due to a 6-year history of infertility. After extensive counselling, the couple elected repeat amniocentesis. Further cytogenetic analysis of repeat amniotic fluid cultures by G-banding and R-banding, molecular genetic analysis with highly polymorphic DNA probes, and quantitative flow cytometry were performed. Results agreed that an unbalanced fetal complement was present. Southern blot analysis with a 5p marker definitively demonstrated a lack of maternal 5p material in the fetus, and in situ hybridization showed a 5q marker at either end of the recombinant chromosome. Flow cytometry was consistent with this interpretation. Because of the advanced gestational age, the parents elected to terminate based on cytogenic results of the second amniocentesis, rather than to wait another 1-2 weeks for results of other methods.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Cytogenetic findings in a prospective series of patients with DiGeorge anomaly.
High-resolution cytogenetics analysis of peripheral blood lymphocytes was done prospectively on 27 of 28 patients with features of DiGeorge anomaly. Twenty-two patients (81%) had normal chromosome studies with no detectable deletion in chromosome 22. Five patients (18%) had demonstrable chromosome abnormalities. Three patients had monosomy 22q11, one due to a 4q;22q translocation, one due to a 20q;22q translocation, and one due to an interstitial deletion of 22q11. One patient had monosomy 10p13, and one patient had monosomy 18q21.33, although the latter had subsequent resolution of T-cell defects. These findings are consistent with the heterogeneity of DiGeorge anomaly but confirm the association with monosomy 22q11 in some cases. However, monosomy 10p13 may also lead to this phenotype. Because of these associated chromosome findings, cytogenetic analyses should be done on patients with suspected DiGeorge anomaly. This is particularly important since many of the abnormalities involving chromosome 22 are translocations that can be familial with a higher recurrence risk. Since only one subtle, interstitial deletion of chromosome 22 was observed, it is not clear whether high-resolution cytogenetic analysis is cost beneficial for all such patients.
Child↗
Linkage of tuberous sclerosis to ABO blood group.
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ABO Blood-Group System↗
Induction of sister-chromatid exchanges and chromosomal aberrations in hematopoietic tissue of a marine fish following in vivo exposure to genotoxic carcinogens.
The development of procedures to assess genetic damage in fish exposed in situ to point sources of aquatic pollution can be expected to contribute to the evaluation of the role of genotoxic contaminants in epizootic neoplasia in fish populations. To this end methods have been developed for assessing the in vivo induction of chromosomal aberrations (CAs) and sister-chromatid exchanges (SCEs) in tissues of a marine teleost, the oyster toadfish, which may be applicable to other species. An alternative to the solid tissue and squash techniques for metaphase preparation permits the resolution of more than 100 SCEs/metaphase in toadfish kidney cells, which have moderately large chromosomes (0.122 pg DNA/chromosome). The bleeding of toadfish which have been injected with 5-bromodeoxyuridine (BrdUrd) and the subsequent use of hematopoietic tissue (kidney) for cytogenetic analysis was shown to increase the metaphase yield and provide a more predictable production of second-division metaphases required for SCE analysis. With these methods linear dose-dependent increases in chromatid-type exchange CAs and SCEs were obtained with i.p. exposure to ethyl methanesulfonate (EMS) and cyclophosphamide (CP). The doses required to double the observed control SCE frequencies (least effective doses) were 170 mg/kg for EMS and 7.4 mg/kg for CP. which are comparable to those reported for rodent bone marrow assays. A BrdUrd-sensitive site for chromatid breakage was observed on a pair of apparently homologous acrocentric chromosomes for the toadfish.
Animals↗
Spina bifida and other neural tube defects.
NTDs, resulting from failure of the neural tube to close during the fourth week of embryogenesis, are the most common severely disabling birth defects in the United States, with a frequency of approximately 1 of every 2000 births. Neural tube malformations involving the spinal cord and vertebral arches are referred to as spina bifida, with severe types of spina bifida involving protrusion of the spinal cord and/or meninges through a defect in the vertebral arch. Depending on the level of the lesion, interruption of the spinal cord at the site of the spina bifida defect causes paralysis of the legs, incontinence of urine and feces, anesthesia of the skin, and abnormalities of the hips, knees, and feet. Two additional abnormalities often seen in children with spina bifida include hydrocephalus and the Arnold-Chiari type II malformation. Despite the physical and particular learning disabilities children with spina bifida must cope with, participation in individualized educational programs can allow these children to develop skills necessary for autonomy in adulthood. Advances in research to uncover the molecular basis of NTDs is enhanced by knowledge of the link between both the environmental and genetic factors involved in the etiology of NTDs. The most recent development in NTD research for disease-causing genes is the discovery of a genetic link to the most well-known environmental cause of neural tube malformation, folate deficiency in pregnant women. Nearly a decade ago, periconceptional folic acid supplementation was proven to decrease both the recurrence and occurrence of NTDs. The study of folate and its association with NTDs is an ongoing endeavor that has led to numerous studies of different genes involved in the folate metabolism pathway, including the most commonly studied thermolabile mutation (C677T) in the MTHFR gene. An additional focus for NTD research involves mouse models that exhibit both naturally occurring NTDs, as well as those created by experimental design. We hope the search for genes involved in the risk and/or development of NTDs will lead to the development of strategies for prevention and treatment. The most recent achievement in treatment of NTDs involves the repair of meningomyelocele through advancements in fetal surgery. Convincing experimental evidence exists that in utero repair preserves neurologic function, as well as resolving the hydrocephalus and Arnold-Chiari malformation that often accompany meningomyelocele defects. However, follow-up is needed to completely evaluate long-term neurologic function and overall improved quality of life. And in the words of Olutoye and Adzick, "until the benefits of fetal [meningomyelocele] repair are carefully elucidated, weighed against maternal and fetal risks, and compared to conventional postnatal therapy, this procedure should be restricted to a few centers that are committed (clinically and experimentally) to investigating these issues."
Animals↗
Benign multicystic peritoneal mesothelioma: cases reports in the family with diverticulosis and literature review.
We report on benign multicystic peritoneal mesothelioma in two siblings whose family had a history of multiple familial diseases including diverticulosis. After a genetic evaluation and a chromosomal analysis, we were not able to identify a specific genetic cause of the family's pattern of disease. We assumed that previous surgical procedures and the chronic inflammatory process from diverticulitis were the underlying etiology. Both patients had multiple recurrences with indolent courses similar to those reported in other cases. After the recurrences, one patient was treated with cystic aspiration and the other with hormones. The cysts in both cases regressed partially but the patients were relieved of their clinical symptoms, for 2 years after cystic drainage in one case and for 5 years after hormonal treatment in the other.
Adult↗