Intercellular adhesion molecule-1: a protective haplotype against multiple sclerosis.

Intercellular adhesion molecule-1 (ICAM-1) and its receptors are adhesion molecules that play a key role in the transmigration of inflammatory cells through the blood-brain barrier, one of the earliest events in multiple sclerosis (MS), which leads to demyelination in the central nervous system. To investigate the role of genes encoding ICAM-1 and its receptors, we used a strategy of genetic linkage and association in 439 case-parent MS families of French origin, well characterized according to HLA status and severity. We demonstrate that the genes encoding ICAM-1 receptors do not influence MS susceptibility or severity. ICAM-1 had a modest, but significant effect on MS genetic susceptibility, independent of HLA and disease severity. We observed a rare, and an as yet unreported, ICAM-1 gene haplotype defined by amino acids K469 and R241 that was never transmitted to patients suggesting a protective effect against MS in our population.

Paraneoplastic limbic encephalitis, a complication of the testicular cancer.

We report a case of paraneoplastic limbic encephalitis related to a testicular neoplasm. The syndrome is characterized by progressive amnesia and psychiatric disturbances resulting from an inflammatory reaction probably related to an immune response to the neuronal proteins expressed by tumors. It is usually associated with small cell lung cancer. In other cases, testicular cancer occurs more frequently than expected. Cranial magnetic resonance imaging may show increased signal intensity in the limbic cortex. Genitourinary examinations are sometimes inadequate. Testicular ultrasonography is recommended if no tumor is detected on the chest and abdominal computed tomography scan. The outcome of the treatment of the testicular cancer on the paraneoplastic syndrome is variable.

[Genetic factors in multiple sclerosis]. / Les facteurs génétiques de la sclérose en plaques.

GENERAL DATA: The clinical manifestations and neuropathological signs of multiple sclerosis have been recognized for more than one hundred years, but the cause remains unknown. EPIDEMIOLOGY: Multiple sclerosis is not evenly distributed throughout the world. There is an important north-south gradient in the northern hemisphere and inversely in the southern hemisphere; multiple sclerosis is more frequent in the higher altitudes. For a given latitude, there is a difference by ethnic origin. These observations indicate that multiple sclerosis is a multifactorial condition determined by both genetic and environmental factors. STRATEGIES OF GENETIC STUDIES: Progress in our knowledge of the human genome and statistical analysis techniques have made it possible to search for genetic factors in multiple sclerosis using two complementary approaches. The first is by anonymous screening and the second is to search for a candidate gene. The HLA locus is the only one with an identified predisposing effect for multiple sclerosis. It only accounts for 10 to 20% of the genetic predisposition for multiple sclerosis and many factors remain to be discovered.

[Andermann syndrome in an Algerian family: suggestion of phenotype and genetic homogeneity]. / Le syndrome d'Andermann dans une famille algérienne: suggestion d'une homogénéité phénotypique et génétique.

Andermann syndrome or Agenesis of the Corpus Callosum with Polyneuropathy (MIM 218000) is an autosomal recessive disease almost exclusively found in Québec. Only few cases have been reported in other populations. The locus for Andermann syndrome was assigned to chromosome 15q13-q15 in French Canadian families. We performed a haplotype analysis with two markers of this chromosomal region in an Algerian consanguineous family with two affected sibs. The children were homozygous for both markers, suggesting genetic homogeneity in Andermann syndrome.

H-2D(b-/-) mice are susceptible to persistent infection by Theiler's virus.

H-2(b) mice are resistant to persistent infection of the central nervous system by Theiler's virus. They clear the infection 7 to 10 days after intracranial inoculation. Resistance maps to the H-2D gene and not to the H-2K gene and is associated with a potent antiviral cytotoxic T-lymphocyte (CTL) response. We used H-2(b) mice in which the H-2D or the H-2K gene had been inactivated to dissect the respective roles of these genes in resistance. We report that H-2D(-/-) but not H-2K(-/-) mice were susceptible to persistent infection. Furthermore, whereas H-2K(-/-) mice mounted a vigorous virus-specific CTL response, similar to that of control C57BL/6 mice, the CTL response of H-2D(-/-) mice was nil or minimal. Using target cells transfected with the H-2D(b) or the H-2K(b) gene, we showed that the H-2K-restricted CTL response against the virus was minimal in H-2D(-/-) mice. These results demonstrate that the H-2D(b) and H-2K(b) genes play nonredundant roles in the resistance to this persistent infection.

[Is multiple sclerosis a disease of viral origin?]. / La sclérose en plaques est-elle une maladie d'origine virale?

MS is a multifactorial disease in which host genetic factors as well as environmental factors may interact. Among them, the role of viruses is still debated since none has been directly or indirectly involved in the disease up to now. The latest candidates are HHV6 and MSRV. Recently, HHV6 antigens have been found in MS brain, but these results require further investigation. MSRV is a retroviral sequence isolated from MS tissue and it belongs to the already known ERV9 family of endogenous retroviruses. Its role in MS is only putative. To conclude, "MS virus" is still unidentified. Nevertheless, the search for a virus in MS should be pursued. In that perspective, animal models illustrate how host immune system interacts with viruses to lead to demyelination, a common feature of a multi-step process of diverse origins.