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Somatic cell genetic analysis of HLA-A, B, C and human beta 2-microglobulin expression.

We have examined the cell surface expression of the human histocompatibility antigens HLA-A, B, C and beta 2-microglobulin (beta 2m) on a human-mouse somatic cell hybrid line. Using specific antibodies and the fluorescence-activated cell sorter (FACS), we viably fractionated and characterized four separate hybrid subpopulations (HLA+,beta 2m+; HLA+,beta 2m-; HLA-,beta 2m+; HLA-,beta 2m-). Hybrid selection based on surface antigen expression resulted in corresponding genetic selection for and against human chromosomes 6 and 15. Studies of the homogeneous hybrid sublines revealed that the presence of human beta 2m in a hybrid cell dramatically increased the surface expression of human HLA-A, B, C and mouse H-2Kk antigens. The results demonstrate the importance of human chromosome-specific surface markers and the fluorescence-activated cell sorter in somatic cell genetic analysis.

Animals↗

Genetic analysis in a patient with recurrent cardiac myxoma and endocrinopathy.

A 60 year-old male was referred for treatment of a cardiac myxoma in the right atrium. He had a past history of left atrial cardiac myxoma at age 49 and pituitary microadenoma related to acromegaly at age 55. He did not have a family history of cardiac neoplasm or endocrinopathy. The intracardiac tumor was resected and its pathology was compatible with myxoma. A diagnosis of Carney complex (CNC) was made because the diagnostic criteria of this neoplastic syndrome were satisfied by the presence of recurrent cardiac myxoma, endocrine tumor and spotty skin pigmentation. In genetic analysis novel frame shift mutation was detected in exon 2 in a heterozygous fashion in the causative gene of CNC, protein kinase A regulatory subunit 1 alpha (PRKAR1A). This genetic mutation is thought to cause haplo-insufficiency of PRKAR1A resulting in tumorigenesis. Although it is the most common, usually benign, cardiac tumor, myxoma can cause a critical clinical situation and thus detecting the PRKAR1A mutation can assist with prognosis.

Acromegaly↗

Caroli's disease: prenatal diagnosis, postnatal outcome and genetic analysis.

Caroli's disease is a rare autosomal recessive condition characterized by cystic dilatation of the intrahepatic bile ducts and infantile polycystic kidney disease. We report a case with Caroli's disease detected prenatally at 33 weeks' gestation with fetal ultrasound findings of a cystic liver mass and echogenic kidneys. Postnatal investigation confirmed enlarged and echogenic kidneys with dilatation of the intrahepatic bile ducts consistent with the diagnosis of Caroli's disease. Genetic analysis of the gene, PKHD1, associated with autosomal recessive polycystic kidney disease (ARPKD) showed that the patient had compound heterozygous mutations, confirming that this early onset Caroli's disease was part of the spectrum of ARPKD. To our knowledge this is the third case of Caroli's disease detected prenatally and the first in which the infant survived.

Caroli Disease↗

Genetic analysis and FISH mapping of the Colourless non-ripening locus of tomato.

Cnr ( Colourless non-ripening) is a dominant pleiotropic ripening mutation of tomato ( Lycopersicon esculentum) which has previously been mapped to the proximal region of tomato chromosome 2. We describe the fine mapping of the Cnr locus using both linkage analysis and fluorescence in situ hybridisation (FISH). Restriction fragment length polymorphism (RFLP)-, amplified restriction fragment polymorphism (AFLP)-, and cleaved amplified polymorphic sequence (CAPS)-based markers, linked to the Cnrlocus were mapped onto the long arm of chromosome 2. Detailed linkage analysis indicated that the Cnr locus was likely to lie further away from the top of the long arm than previously thought. This was confirmed by FISH, which was applied to tomato pachytene chromosomes in order to gain an insight into the organisation of hetero- and euchromatin and its relationship to the physical and genetic distances in the Cnr region. Three molecular markers linked to Cnr were unambiguously located by FISH to the long arm of chromosome 2 using individual BAC probes containing these single-copy sequences. The physical order of the markers coincided with that established by genetic analysis. The two AFLP markers most-closely linked to the Cnr locus were located in the euchromatic region 2.7-cM apart. The physical distance between these markers was measured on the pachytene spreads and estimated to be approximately 900 kb, suggesting a bp:cM relationship in this region of chromosome 2 of about 330 kb/cM. This is less than half the average value of 750 kb/cM for the tomato genome. The relationship between genetic and physical distances on chromosome 2 is discussed.

Journal Article↗

Ozone-induced acute lung injury: genetic analysis of F(2) mice generated from A/J and C57BL/6J strains.

Acute lung injury (or acute respiratory distress syndrome) is a devastating and often lethal condition. This complex disease (trait) may be associated with numerous candidate genes. To discern the major gene(s) controlling mortality from acute lung injury, two inbred mouse strains displaying contrasting survival times to 10 parts/million ozone were identified. A/J (A) mice were sensitive [6.6 +/- 1 (SE) h] and C57BL/6J (B) were resistant (20.6 +/- 1 h). The designation for these phenotypes was 13 h, a point that clearly separated their survival time distributions. Our prior segregation studies suggested that survival time to ozone-induced acute lung injury was a quantitative trait, and genetic analysis identified three linked loci [acute lung injury-1, -2, and -3 (Ali1-3, respectively)]. In this report, acute lung injury in A or B mice was characterized histologically and by measuring lung wet-to-dry weight ratios at death. Ozone produced comparable effects in both strains. To further delineate genetic loci associated with reduced survival, a genomewide scan was performed with F(2) mice generated from the A and B strains. The results strengthen and extend our initial findings and firmly establish that Ali1 on mouse chromosome 11 has significant linkage to this phenotype. Ali3 was suggestive of linkage, supporting previous recombinant inbred analysis, whereas Ali2 showed no linkage. Together, our findings support the fact that several genes, including Ali1 and Ali3, control susceptibility to death after acute lung injury. Identification of these loci should allow a more focused effort to determine the key events leading to mortality after oxidant-induced acute lung injury.

Acute Disease↗

Heterozygous and homozygous factor h deficiencies associated with hemolytic uremic syndrome or membranoproliferative glomerulonephritis: report and genetic analysis of 16 cases.

Factor H (FH) is the major regulatory protein of the complement alternative pathway, with a structure consisting of a tandem array of 20 homologous units, called short consensus repeats (SCR). Reported are 16 FH-deficient patients. Among six patients with homozygous deficiency, four presented with membranoproliferative glomerulonephritis, and two with atypical hemolytic uremic syndrome (HUS). The ten other patients had heterozygous FH deficiency and developed atypical HUS. HUS onset occurred from birth to midadulthood, and disease progression was variable. Four children with homozygous or heterozygous FH deficiency and HUS underwent renal transplantation, which was successful in three but failed as a result of recurrence of HUS in one patient. All but one patient exhibited alternative pathway-mediated complement consumption, with no detectable FH antigenic levels or with 50% immunochemical or functional FH levels in the case of complete or partial deficiency, respectively. The molecular mechanisms of the deficiency were documented in all cases by exon-specific sequencing analysis. These mechanisms included nucleotide substitutions, insertion, or deletion located in SCR 2, 7, 11, 13, 15, and 20, leading to an amino acid substitution or to a stop codon. This report emphasizes the variability in the clinical progression of kidney diseases associated with FH deficiencies. Genetic analysis reveals the molecular abnormalities associated with FH deficiencies to be polymorphous.

Adult↗

Genetic analysis and complementation by germ-line transformation of lethal mutations in the unc-22 IV region of Caenorhabditis elegans.

The subject of this study is the organization of essential genes in the 2 map-unit unc-22 IV region of the Caenorhabditis elegans genome. With the goal of achieving mutational saturation of essential genes in this region, 6491 chromosomes mutagenized with ethyl methanesulfonate (EMS) were screened for the presence of lethal mutations in the unc-22 region. The genetic analysis of 21 lethal mutations in the unc-22 region resulted in the identification of 6 new essential genes, making a total of 36 characterized to date. A minimum of 49 essential genes are estimated to lie in this region. A set of seven formaldehyde-induced deficiencies of unc-22 and surrounding loci were isolated to facilitate the positioning of essential genes on the genetic and physical maps. In order to study essential genes at the molecular level, our approach was to rescue lethal mutations by the injection of genomic DNA in the form of cosmid clones into the germ-line of balanced heterozygotes carrying a lethal mutation. The cosmid clones containing let-56 and let-653 were identified by this method.

Animals↗

Harnessing the power of forward genetics--analysis of neuronal diversity and patterning in the zebrafish retina.

The seven major cell classes of the vertebrate retina are organized with remarkable precision into distinct layers. The appearance of this architecture during embryogenesis raises two questions of general importance. How do individual cell classes acquire their specialized structures and functions if they all originate from a morphologically uniform cell population? What mechanisms are responsible for the formation of such a complex and exact pattern? Recent advances present an opportunity to apply the tools of forward genetic analysis to identify mutations that affect these mechanisms in zebrafish. Molecular characterization will follow, providing insight into the basis of neuronal patterning in the vertebrate CNS.

Animals↗

Rapid-onset dystonia-parkinsonism: a clinical and genetic analysis of a new kindred.

BACKGROUND: Rapid-onset dystonia-parkinsonism (RDP) is an autosomal dominant disorder linked to chromosome 19q13 that is characterized by sudden onset of primarily bulbar and upper limb dystonia with parkinsonism. METHODS: The authors evaluated 12 individuals from three generations of an Irish family and obtained detailed medical records on a deceased member. The authors describe the clinical, psychiatric, and genetic features of the affected individuals. RESULTS: Five of eight affected members developed sudden-onset (several hours to days) dystonia with postural instability. Four of the five also had bulbar symptoms. Two have stable focal or segmental limb dystonia. One has intermittent hemidystonia with dysarthria that comes on abruptly in times of stress or anxiety. Three had a history of profound difficulty socializing, and at presentation two developed depression. Three patients had a trial of dopamine agonists without benefit. Genetic analysis suggests linkage to chromosome 19 with lod score of 2.1 at zero recombination. CONCLUSION: This is the third reported family with chromosome 19q13 rapid-onset dystonia-parkinsonism. Psychiatric morbidity appeared common in affected members of this family and may be part of the RDP phenotype.

Adolescent↗

Diagnosis of Alexander disease in a Japanese patient by molecular genetic analysis.

Alexander disease is a leukodystrophy that is neuropathologically characterized by the presence of numerous Rosenthal fibers in astrocytes. Recently, mutations in the gene encoding glial fibrillary acidic protein (GFAP) were identified in patients with Alexander disease. We sequenced the GFAP gene of a Japanese girl who presented with typical symptoms of Alexander disease but in whom the diagnosis was not proven by histopathology. We identified a missense mutation, R239C, which is identical to the mutation previously reported to be most frequent. As was the case in previously described patients, our patient was also heterozygous for the de novo mutation. Interestingly, despite the fact that this is a de novo mutation, R239C was found to be common in different ethnic groups, implying that the site is a "hot spot" for mutagenesis. Molecular genetic analysis now makes the antemortem diagnosis of Alexander disease possible.

Brain↗

Population genetic analysis of the Plasmodium falciparum erythrocyte binding antigen-175 (eba-175) gene.

The Plasmodium falciparum erythrocyte binding antigen-175 gene (eba-175) has highly divergent allelic segments (Cseg and Fseg) in one part of the gene (region III), but only a small number of single nucleotide polymorphisms (SNPs) in the rest of the sequence. Here, evidence for the possible importance of the Cseg/Fseg dimorphism was sought in a molecular population genetic analysis of the gene. First, allele frequency distributions were determined for the Cseg/Fseg dimorphism and five SNPs in a sample of five populations in Africa. The inter-population variance in frequencies was higher for Cseg/Fseg (F(ST)=0.18) than for the SNPs (F(ST) values from 0.03 to 0.10), but these values were entirely dependent on the inclusion of one particularly divergent population (Sudan). Second, linkage disequilibrium was measured among the intragenic loci. There was the expected trend of declining linkage disequilibrium with increasing molecular distance, but it is notable that the Cseg allele was in absolute linkage disequilibrium with the two flanking SNPs, whereas the Fseg allele was associated with a broader range of SNP haplotypes. Finally, there was no association between the Cseg/Fseg alleles of eba-175 in parasites and the M/N alleles of the glycophorin A erythrocyte receptor in the human subjects.

Africa↗

Building a synapse: genetic analysis of glutamatergic neurotransmission.

Ionotropic glutamate receptors (iGluRs) are a critical component of the vertebrate central nervous system and mediate the majority of rapid excitatory neurotransmission. However, iGluRs are not self-regulating molecules and require additional proteins in order to function properly. Understanding the molecular architecture of functional glutamatergic synapses is therefore an important challenge in neurobiology. To address this question, we combine the techniques of genetics, molecular biology and electrophysiology in the nematode Caenorhabditis elegans. To date, genetic analysis has identified a number of genes required to build a glutamatergic synapse, including the CUB-domain transmembrane protein, SOL-1, which is thought to act as an auxiliary subunit that directly modifies iGluR function. Identifying and characterizing new proteins, such as SOL-1, in the relatively simple nervous system of the worm can contribute to our understanding of how more complex vertebrate nervous systems function.

Animals↗

Genetic analysis for insulitis in NOD mice.

Non-obese diabetic (NOD) mice spontaneously develop diabetic signs akin to those of Type I diabetes in man. Insulitis, i.e., lymphocytic infiltration around and into the pancreatic islets is one of the characteristics of such mice. It is also the etiologic pathological lesion in the development of diabetes mellitus in NOD mice. Thus, we chose insulitis as a marker for genetic analysis of the development of diabetes mellitus in NOD mice and clarified the mode of its inheritance. In breeding studies between NOD and C57BL/6J mice, insulitis was not observed in the F1 and (F1 X C57BL/6J) backcross generations, but was found with incidences of 3.9% in females and 1.4% in males in the F2 generation and 23.7% in females and 12.1% in males in the (F1 X NOD) backcross generation. These incidences in the F2 and (F1 X NOD) backcross females corresponded approximately to 1/16 and 1/4 of the incidences of 89.7% in the NOD females, respectively. A similar relationship was observed between the F2 and (F1 X NOD) backcross males and the NOD males. When the gene expressivity of both sexes for a double recessive homozygote was assumed to be the incidences of insulitis in 9-week-old NOD females and males, respectively, the expected numbers of both sexes with and without insulitis in the F2 and backcross generations agreed well with the observed ones. These observations suggest that two recessive genes on independent autosomal chromosomes are necessary for the development of insulitis in NOD mice.

Animals↗

Genetic analysis of adipogenesis through peroxisome proliferator-activated receptor gamma isoforms.

Peroxisome proliferator-activated receptor (PPAR) gamma is a nuclear receptor that is a key regulator of adipogenesis and is present in two isoforms generated by alternative splicing, PPARgamma1 and PPARgamma2. Studies of the ability of each isoform to stimulate fat differentiation have yielded ambiguous results, in part because PPARgamma stimulates its own expression. We have thus undertaken a formal genetic analysis using PPARgamma-null fibroblast cell lines to assess the specific role of each individual isoform in adipogenesis. We show here that both PPARgamma1 and PPARgamma2 have the intrinsic ability to stimulate robust adipogenesis. Adipose cells stimulated by either PPARgamma1 or PPARgamma2 express a similar gene profile and show similar responses to insulin. However, in response to low ligand concentrations, PPARgamma2 shows a quantitatively greater ability to induce adipogenesis. Analyses involving coactivator binding and transcriptional assays indicate that PPARgamma2 has an enhanced ability to bind components of the DRIP/TRAP complex, coactivators required for fat differentiation.

Adipocytes↗

Molecular genetic analysis of the V kappa Ser group associated with two mouse light chain genetic markers. Complementary DNA cloning and southern hybridization analysis.

Previous studies (21) have shown that two mouse kappa light (L) chain variable (V) region polymorphisms, the IB-peptide and Efla markers, reflect expression of a characteristic group of V kappa regions, called V kappa Ser, by some inbred strains and not others. Expression of V kappa Ser is controlled by a locus on chromosome 6, the chromosome that contains the kappa locus. To further characterize this V kappa group and begin to analyze the basis for its strain-specific expression, full-length complementary DNA (cDNA) copies were produced of L chain mRNA from the M75 myeloma that had been induced in the C.C58 strain of mice, and which produces a V kappa Ser L chain. The C.C58 strain is congenic with BALB/cAn, differing in the region of chromosome 6 that controls expression of the V kappa polymorphisms and the Lyt-2 and Lyt-3 T cell alloantigens. The complete nucleotide sequence of this cloned cDNA was determined and compared with the nucleotide sequences the most closely related BALB/c myeloma L chains known. Results indicated significant differences throughout the variable region, but particularly toward the 5' portion of the sequence. A probe corresponding to 200 bp of the 5' end of the cloned V kappa Ser cDNA was used in Southern hybridizations of restriction digests of liver DNA from a number of inbred, recombinant, and recombinant inbred strains. Under stringent hybridization conditions, one strongly-hybridizing fragment was observed in Bam HI, Hind III, and Eco RI digests, and based on the size of the fragments, strains could be organized into two groups. The presence of strongly hybridizing Bam HI, Hind III, and Eco RI fragments of 3.2, 2.8, and 2.1 kb, respectively, was found to correlate completely with expression by the strain of the IB-peptide and Efla markers. All nonexpressor strains yielded hybridizing fragments of 7.8, 8.4, and 2.8 kb, respectively. Possible explanations for strain-specific expression of V kappa Ser-associated phenotypic markers are discussed.

Amino Acid Sequence↗

Genetic analysis of the marine manganese-oxidizing Bacillus sp. strain SG-1: protoplast transformation, Tn917 mutagenesis, and identification of chromosomal loci involved in manganese oxidation.

Mature spores of the marine Bacillus sp. strain SG-1 bind and oxidize manganese(II), thereby becoming encrusted with a manganese(IV) oxide. Both the function and mechanism of this oxidation are unknown, although evidence suggests that spore coat proteins are involved. To further study this phenomenon, methods of genetic analysis were developed for SG-1. By a modified protoplast transformation procedure, SG-1 was transformed (approximately 100 transformants per micrograms of DNA) with several different plasmids of gram-positive origin. Transposon Tn917, delivered on the temperature-sensitive plasmid pLTV1, was used to generate mutants of SG-1. Conditions were established that allowed 98% plasmid loss and insertions to be recovered at a frequency of 10(-3). Each mutant was found to be the result of a single insertion event. Restriction analysis of 27 mutants that do not oxidize manganese but still sporulate localized 17 of the insertions within two regions of the chromosome (termed Mnx regions), and a physical map of these regions was generated. Analysis of 18 transposon integrants in which manganese oxidation was unaffected revealed random transposon integration, with none of their insertions mapping within the Mnx regions. The Mnx regions were cloned from wild-type SG-1, and the largest region, carried on the lactococcal plasmid pGK13, was used to complement in trans one of the nonoxidizing mutants. These results demonstrate that the Mnx regions encode factors that are required for the oxidation of manganese, and this represents the first report identifying genes involved in bacterial manganese oxidation.

Bacillus↗

Genetic analysis of the RNASEL gene in hereditary, familial, and sporadic prostate cancer.

PURPOSE: The RNASEL gene has been proposed as a candidate gene for the HPC1 locus through a positional cloning and candidate gene approach. Cosegregation between the truncating mutation E265X and disease in a hereditary prostate cancer (HPC) family and association between prostate cancer risk and the common missense variant R462Q has been reported. To additionally evaluate the possible role of RNASEL in susceptibility to prostate cancer risk, we performed a comprehensive genetic analysis of sequence variants in RNASEL in the Swedish population. EXPERIMENTAL DESIGN: Using 1624 prostate cancer cases and 801 unaffected controls, the truncating mutation E265X and five common sequence variants, including the two missense mutations R462Q and D541E, were evaluated for association between genotypes/haplotypes and prostate cancer risk. RESULTS: The prevalence of E265X carriers among unaffected controls and prostate cancer patients was almost identical (1.9 and 1.8% in controls and cases, respectively), and evidence for segregation of E265X with disease was not observed within any HPC family. Overall, the analyses of common sequence variants provided limited evidence for association with prostate cancer risk. We found a marginally significant inverse association between the missense mutation D541E and sporadic prostate cancer risk (odds ratio, 0.77; 95% confidence interval, 0.59-1.00) and reduced risk of prostate cancer in carriers of two different haplotypes being completely discordant. CONCLUSIONS: Considering the high quality in genotyping and the size of this study, these results provide solid evidence against a major role of RNASEL in prostate cancer etiology in Sweden.

Adult↗

dCAPS, a simple technique for the genetic analysis of single nucleotide polymorphisms: experimental applications in Arabidopsis thaliana genetics.

PCR-based detection of single nucleotide polymorphisms is a powerful tool for the plant geneticist. Cleaved amplified polymorphic sequence analysis is the most widely used approach for the detection of single nucleotide polymorphisms. However, this technique is limited to mutations which create or disrupt a restriction enzyme recognition site. This paper presents a modification of this technique where mismatches in a PCR primer are used to create a polymorphism based on the target mutation. This technique is useful for following known mutations in segregating populations and genetic mapping of isolated DNAs used for positional based cloning of new genes. In addition, a computer program has been developed that facilitates the design of these PCR primers.

Arabidopsis↗