Genetic localization of a locus controlling the intensity of infection by Schistosoma mansoni on chromosome 5q31-q33.

Three hundred million individuals are at risk of infection by schistosomes and around 200,000 die each year of this disease. Severe clinical disease in schistosomiasis is often the consequence of heavy infection which, in several endemic areas, are determined largely by the susceptibility/resistance of individuals. Previously, we reported evidence, based on a segregation analysis in Brazilian pedigrees, that intensity of infection by Schistosoma mansoni was influenced by a major gene, indicating that host genetic factors are probably critical in controlling schistosome infection and disease development. To localize this gene, referred to as SM1, we performed a genome-wide study on 142 Brazilian subjects belonging to 11 informative families Our results show a linkage to only one region, on chromosome 5q31-q33, with maximum two-point lod scores of +4.74 and +4.52 for D5S636 and the colony stimulating factor-1 receptor marker (CSF1R), respectively. This was corroborated by multipoint analysis, indicating a close proximity to CSF1R as the most likely location of SM1. This region contains several candidate genes encoding immunological molecules that were shown to play important roles in human protection against schistosomes.

Full results of the genome-wide scan which localises a locus controlling the intensity of infection by Schistosoma mansoni on chromosome 5q31-q33.

Three hundred million individuals are at risk of infection by schistosomes, and thousands die each year of severe hepatic disease. Previous studies have shown that the intensity of infection by Schistosoma mansoni in a Brazilian population is controlled by a major gene, denoted as SM1. We report here the full results of a genome-wide search that was performed on this population to localise SM1. Two hundred and forty-six microsatellites were used for the primary map, and only one region in 5q31-q33 provided significant evidence of linkage. SM1 was subsequently mapped to this region, which contains several genes encoding cytokines or cytokine receptors which are involved in protection against schistosomes. Three additional regions, 1p22.2, 7q36 and 21q22-22-qter, yielded promising, although not significant, lod-score values. These regions contain candidate genes encoding cytokines or molecules relevant to anti-schistosome immunity.

Malignant hyperthermia and central core disease: analysis of two families with heterogeneous clinical expression.

We report two families both presenting with malignant hyperthermia susceptibility and "core" or "core-like" changes in the muscle tissue. Combined analysis of the malignant hyperthermia phenotype and the histochemical findings demonstrates the complexity of their association and highly suggests genetic heterogeneity of malignant hyperthermia and central core diseases.

Genome search for additional human loci controlling infection levels by Schistosoma mansoni.

Schistosomiasis is a major public health problem in many developing countries. Previous studies have shown that infection levels by Schistosoma mansoni in a Brazilian population is controlled by a major gene, denoted as SM1, which was mapped to chromosome 5q31-q33 by use of a model-based (logarithm of the odds [lod] score) analysis method. The present study is an autosome-wide scan searching for additional human loci implicated in the regulation of S. mansoni infection intensities. The weighted pairwise correlation model-free linkage method was used in order to consider large pedigrees and to conduct a 2-locus analysis (i.e., to search for a second locus taking into account linkage to 5q31-q33). The most significant linkage results were again obtained in the 5q31-q33 region. Two additional regions provided linkage results with significance levels around 0.001, 1p21-q23 (results independent of 5q31-q33) and 6p21-q21 (results in interaction with 5q31-q33). The investigation of these regions, which contain some candidate genes, is ongoing in other populations to confirm the role of these regions.

Linkage analysis of blood Plasmodium falciparum levels: interest of the 5q31-q33 chromosome region.

There is accumulating evidence for the involvement of genetic factors in the human response to malaria infection, mostly based on results obtained in studies of severe clinical malaria. The role of major gene(s) controlling blood parasitemia levels in human malaria has also been detected by means of segregation analysis. To confirm and to localize such gene(s), we performed a sib-pair linkage analysis investigating the role of five candidate chromosomal regions: 6p21 (HLA-tumor necrosis factor region), 2q13-q21 (genes coding for interleukin-1 alpha and beta), 14q11 (locus coding for the alpha chain of T cell antigen receptor), 7q35 (gene cluster for the beta subunit of T cell receptor), and 5q31-q33, which includes several candidate genes and was recently linked to a locus controlling infection levels by Schistosoma mansoni, denoted as SM1. The analysis was carried out on nine families from a southern Cameroon village, and the phenotype under study was blood infection levels with Plasmodium falciparum. No linkage was found with any of the four markers outside the 5q31-q33 region. A trend in favor of linkage was observed in the distal part of the 5q31-q33 region, especially with the marker D5S636 (P < 0.05 using the Monte Carlo P value), which was the marker that provided the highest evidence for linkage with SM1. These results suggest that a locus influencing P. falciparum levels in malaria could be located in the same genetic region as that containing SM1, indicating that the 5q31-q33 region may be critical in the control of different parasite infections.

Failure to replicate linkage between chromosome 5q11-q13 markers and schizophrenia in 28 families.

Sherrington et al. (1988) reported linkage between markers located on the 5q11-q13 region of chromosome 5 and schizophrenia in five Icelandic and two British families. To date, however, all attempts to replicate the initial finding have failed. Using three markers of chromosome 5, we have studied 28 additional French pedigrees. When our data were analyzed both with parametric (i.e., lod scores) and nonparametric methods, we found no evidence of linkage. Thus, we were unable to replicate the earlier report by Sherrington et al.

Clinical subtypes and age at onset in schizophrenic siblings.

This study examines the concordance of clinical subtypes and age at onset of schizophrenia in 42 sibships of multiply affected schizophrenic patients. Subtypes were defined by four major diagnostic systems (DSM-III, DSM-III-R, ICD-10, and Tsuang-Winokur criteria) and rated both for the first hospitalization and long-term diagnosis. When a sibship method was used, no concordance for subtypes was found in siblings. Age at onset, analyzed as a continuous variable with the intraclass correlation method, was found to be correlated in siblings. This finding suggest that the search for continuous traits distributed in families of schizophrenic patients might constitute an alternative to discrete category-based family studies.

Relationship of HLA to schizophrenia not supported in multiplex families.

The role of the human histocompatibility complex (HLA) in the pathogenesis of schizophrenia has been suggested in previous reports. We conducted a genetic study in 33 new families. Our linkage analysis, which used the affected sib-pair method, did not provide evidence for nonrandom assortment. Moreover, the results of an association study using the "haplotype relative risk" method failed to confirm the positive association between HLA A9 and schizophrenia. Taken together, our data did not support any relationship of HLA type to schizophrenia.

Subtyping familial schizophrenia: reliability, concordance, and stability.

This report examines the reliability, concordance, and long-term stability of the subtypes of schizophrenia defined by four major diagnostic systems (DSM-III, DSM-III-R, ICD-10, and Tsuang-Winokur criteria) and rated both for the first hospitalization and for a best estimate diagnosis reflecting lifetime evolution of symptomatology. Schizophrenics studied belonged to two samples of multiply affected families, namely a sample selected in France and a sample of non-metropolitan French identified in the island of La Réunion. ICD-10 and DSM-III-R show opposite stringency regarding subtyping of schizophrenia, with DSM-III-R having a narrow and ICD-10 a broader definition of specific subtypes. Long-term stability of each subtype was fairly good, stability being the highest for hebephrenics and only intermediate for paranoid and undifferentiated subtypes. Comparison of two different cultural and geographical regions reveals an overall similarity of subtype frequencies in familial schizophrenia. The implications of the results for the choice of diagnostic procedures in family studies of schizophrenia are discussed.

[Congenital muscular dystrophy with merosin deficiency: clinical, histopathological, immunocytochemical and genetic analysis]. / Dystrophie musculaire congénitale avec déficience en mérosine: analyse clinique, histopathologique, immunocytochimique et génétique.

A selective deficiency of a specific laminin isovariant, merosin made of M, B1 and B2 chains, was found in a series of 17 patients affected with congenital muscular dystrophy (CMD). The merosin deficiency was complete in 15 cases, and almost complete in two cases. An overexpression of the laminin A chain was seen in these biopsies, while B1 and B2 chains were normally expressed. Comparison of the clinical data with a series of 18 "merosin-non deficient" cases showed that the "merosin-deficient" cases were forming a more homogenous group than the "non-deficient" one. Hypotonia, contractures, motor development delay were generally more severe in the "merosin-deficient" series of cases. Moreover, white matter alterations were seen in most cases explored by MRI or scan imaging. A genetic linkage with a 6q2 locus, corresponding to the M chain gene localization, was found in a panel of informative families from French and Turkish origin with "merosin deficient" CMD. "Merosin non-deficient" families did not map on this locus. So, the "merosin-deficient" CMD can be considered as a peculiar entity within the group of Congenital Muscular Dystrophies.

[Familial forms of schizophrenia. Cytogenetic study]. / Formes familiales de schizophrénie. Etude cytogénétique.

As a preliminary step in the search for chromosomal location of a susceptibility gene predisposing to schizophrenia, cytogenetic screening of patients might be useful. Search for chromosomal aberrations has successfully directed and accelerated the identification of several disease genes, such as the Duchenne muscular dystrophy gene, retinoblastoma, Burkitt's lymphoma and chronic myeloïd leukemia. Although karyotypes abnormalities do not account for a large portion of cases of Schizophrenia, the two candidate regions predisposing to this disease resulted from observation of chromosomal abnormalities. First, the identification of a partial trisomy of the 5q11-q13 region (Basset et al., 1988) led Sherrington et al. (1988) to report a positive linkage with markers localized on the long arm of chromosome 5, which has not yet been replicated (Kauffman et al., 1989; Kennedy et al., 1988; St Clair et al., 1989). Second, on the basis of frequent cytogenetic abnormalities of the sex chromosome (DeLisi, 1985) in addition to epidemiological observations, Crow (1988) suggested that there could be a locus for psychosis within the pseudoautosomal region, a data which has been recently confirmed (Collinge et al., 1991). With the hypothesis that such aberrations could be more frequent among schizophrenics who have at least one affected first-degree relative, we undertook cytogenetic screening on a sample recruited from consecutive psychiatric admissions to a Psychiatric facility (Hôpital Saint Paul) involving patients living in a limited geographical area on the island of La Réunion, a French Department in the Indian Ocean.(ABSTRACT TRUNCATED AT 250 WORDS)

Evidence for the two-step binding of ATP to myosin subfragment 1 by the rapid-flow-quench method.

1. The initial steps on the myosin ATPase (EC 3.6.1.3) pathway are taken to be: (formula; see text) A two-step binding for ATP is assumed, but the evidence for it is unconvincing; because of the rapidity of the process unambiguous values for K1 and K2 are not available. 2. We investigated the myosin mechanism by the chemical flow-quench technique. Reaction mixtures containing [gamma-32P]ATP plus myosin subfragment 1 were quenched in unlabelled ATP (ATP chase) or acid (Pi burst). 3. We show that the ATP-chase method can lead directly to unambiguous values for K1 and k+2. 4. The binding process was slowed down by 40% ethylene glycol. It was studied as a function of the ATP concentration. A limiting plateau resulted, showing a two-step binding for ATP, and values for K1 and k+2 were obtained. 5. K1 and k+2 are rather sensitive to the experimental conditions. Ethylene glycol and lowering of the pH decrease both constants, but an increase in KCl concentration increases them. This suggests that the binding of ATP to myosin is of an electrostatic nature. 6. The Pi-burst method can lead directly to k+3 + k-3, but under certain conditions the kinetics are governed by K1 and k+2. This uncertainty of the interpretation of Pi-burst experiments is discussed.

[Genetic predisposition to bilharziasis in humans: research methods and application to the study of Schistosoma mansoni infection]. / Prédisposition génétique à la bilharziose chez l'homme: méthodes de recherche et application à l'étude de l'infection par Schistosoma mansoni.

The development of genetic epidemiology methods using recent human genetic mapping information together with the growing availability of candidate genes has led to major advances in the identification of host genes in human schistosomiasis. Two phenotypes have been studied so far in the infection by Schistosoma mansoni: infection levels by the parasite as measured by the faecal egg counts, and the severe hepatic fibrosis caused by S. mansoni assessed by ultrasound examination. The first study was performed on Brazilian pedigrees and provided strong evidence for a major gene controlling infection levels by S. mansoni denoted as SM1 which was mapped to chromosome 5q31-q33. This region contains several candidate genes involved in the regulation of the Th1/Th2 response, and the direct role of polymorphisms located within these genes is under investigation. The second study conducted in Sudan also showed the presence of a major gene influencing the development of severe hepatic fibrosis due to S. mansoni infection denoted as SM2. This gene is not located in the 5q31-q33 region, but maps to chromosome 6q22-q23 and is closely linked to the IFN-gamma R1 gene encoding the receptor of the strongly anti-fibrogenic cytokine Interferon-gamma. These findings indicate that two distinct genetic loci control human predisposition to schistosomiasis, SM1 located in the 5q31-q33 region which is likely to play a role in the Th1/Th2 differentiation, and SM2 in 6q22-q23 influencing disease progression with a possible involvement in the regulation of IFN-gamma.

Cryoenzymic studies on myosin subfragment 1: perturbation of an enzyme reaction by temperature and solvent.

The effects of temperature and solvent on myosin subfragment 1 ATPase have been studied. Under all of the conditions used the data could be fitted to the Bagshaw - Trentham pathway: (formula; see text) Ethylene glycol (40%) was used as the cryosolvent ; this makes K1 and k+2 measurable and allows for temperature studies over an extensive temperature range (+35 to -20 degrees C) and thus to reasonably accurate thermodynamic parameters. The following techniques were used: ATP chase (for K1 and k+2); Pi burst (k+2 or k+3 + k-3); single-turnover Pi burst [k0 = k +4K3 /(1 + K3)] absorption stopped flow (k+2 or k+3 + k-3); steady state (k+6 or k0). Myosin provides examples of causes for nonlinear Arrhenius and van't Hoff plots. A temperature-induced structural change is exemplified by a "jump" in an Arrhenius plot of k+2 and "breaks" in van't Hoff plots of K1 and K3. A change in rate-limiting step is illustrated from stopped-flow experiments ( kobsd approximately k+2 at low and approximately k+3 + k-3 at high temperatures) and steady-state experiments (kcat approximately k+6 at low and approximately k0 at high temperatures). A third cause is illustrated by k0: an Arrhenius plot of k0 is nonlinear since there is a break in K3. These studies illustrate the use of temperature perturbation as a way of revealing reaction intermediates and of defining the conditions required for the isolation of a particular intermediate.(ABSTRACT TRUNCATED AT 250 WORDS)

Genetics of parasitic infections.

Parasites cause much suffering mainly in countries of the southern hemisphere. Hundreds of millions of individuals are infected by schistosomes, leishmanias, plasmodiums, trypanosomes, and various other parasites, and severe clinical disease occurs in a sizable fraction of the infected population causing death and severe sequelae. The outcome, asymptomatic, subclinical or clinical disease, of an infection depends mostly on the parasite and on its host. Several groups analyzing the genetics of human susceptibility to parasites have began to identify the critical steps of the pathogenic mechanisms in a few parasitic infections such as malaria and schistosomiasis. The present article, which is not meant to be an exhaustive review of the field, illustrates the progresses made in this field from pioneer studies in animals to works in endemic populations using modern strategies of human genetics.

Mapping of the formin gene and exclusion as a candidate gene for the autosomal recessive form of limb-girdle muscular dystrophy.

Limb-Girdle Muscular Dystrophy (LGMD) is a myopathy with clinical and transmission heterogeneity. The recessive form, LGMD2, has been recently mapped by linkage analysis to 15q. As an attempt to identify the gene involved in this pathology, we tested as candidate gene the LD locus, called LD for limb deformity. This gene has recently been identified and mapped to chromosome 15q13-q14. It is homologous to the murine formin gene which is localized to mouse chromosome 2. Mutations in this murine gene have been shown to cause limb deformity and kidney defect. YAC clones containing the LD gene were isolated and utilised to confirm the cytogenetic localisation. Internal DNA polymorphisms of the LD locus were analyzed in LGMD2 and CEPH families. The LD gene was mapped between the alpha cardiac actin gene and the D15S24 locus. Crossovers between the LGMD2 and the LD loci excluded the LD gene as a candidate for LGMD2.

Evidence for a pseudoautosomal locus for schizophrenia. I: A replication study using phenotype analysis.

A locus for schizophrenia within the pseudoautosomal region of chromosomes X and Y has been suggested by Crow on the basis of epidemiological data. The present report replicates this finding in a sample of 38 French multiply affected families with schizophrenia. Sibship and pairwise analysis, with or without weighted-pair correction, with three different systems of family classifications, showed there to be an excess of same-sex pairs in paternally derived sibships, as predicted by the pseudoautosomal hypothesis.

Use of a simple method for the Epstein-Barr virus transformation of lymphocytes from members of large families of Réunion Island.

A simple method for the preparation of lymphoblastoid cell lines from small amounts (100 microliter) of frozen whole blood is described. A success score greater than 90% was obtained for EBV transformations using blood samples which had been collected several months before the infection. Due to the simplicity of the technique, up to 80 samples could be processed per day. This technique was used to prepared 242 permanent cell lines from 13 large families from Réunion Island showing blood group H deficiency. These cell lines are now available for genetic studies.