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1. Lymphoproliferative syndrome with autoimmunity: A possible genetic basis for dominant expression of the clinical manifestations

Author

Frédéric Rieux-Laucat, Blachère, S., Danielan, S., Villartay, J. P., Oleastro, M., Solary, E., Bader-Meunier, B., Arkwright, P., Pondaré, C., Bernaudin, F., Chapel, H., Nielsen, S., Berrah, M., Fischer, A., and Le Deist, F.

Subjects
Adult, Male, Heterozygote, Adolescent, T-Lymphocytes, Apoptosis, Hypersplenism, Autoimmune Diseases, Uveitis, Genetic Heterogeneity, Hypergammaglobulinemia, Humans, Point Mutation, Genetic Predisposition to Disease, fas Receptor, Child, Genes, Dominant, Age Factors, Infant, Exons, Lymphoproliferative Disorders, Amino Acid Substitution, Splenomegaly, Splenectomy, Female, Follow-Up Studies
Abstract

Fas (CD95/Apo-1) mutations were previously reported as the genetic defect responsible for human lymphoproliferative syndrome associated with autoimmune manifestations (also known as autoimmune lymphoproliferative syndrome or Canale-Smith syndrome). We have identified 14 new heterozygous Fas mutations. Analysis of patients and families allow us to further dissect this syndrome with regards to the relationship between Fas mutations, inheritance pattern, and phenotype as observed on long-term follow-up. In vitro studies show that lymphocytes from all Fas mutant carriers exhibit a Fas-antibody-induced apoptosis defect. However, among the 8 inherited mutations, 4 of 4 Fas missense mutations were associated with high clinical penetrance, whereas 3 of 4 mutations leading to a truncated Fas product were associated with variable clinical penetrance. This suggests that a second defect, in another yet undefined factor involved in apoptosis and/or lymphoproliferation control, is necessary to induce full clinical expression of the disease. These results also indicate that the currently available antibody-mediated in vitro apoptosis assay does not necessarily reflect the in vivo ability of abnormal Fas molecules to trigger lymphocyte death. In addition, we found that lymphoproliferative manifestations resolved with age, whereas immunological disorders [ie, hypergammaglobulinemia and detection of TcR alphabeta(+) CD4(-) CD8(-) lymphocytes] persisted. This observation suggests that Fas-mediated apoptosis plays a more important role in lymphocyte homeostasis in early childhood than later on in life.

2. Layers Heights Randomness Effect on Seismic Response of a Site in Algiers (Algeria)

Author

Badaoui, M., Berrah, M. K., Mebarki, A., Badaoui, M., Berrah, M. K., and Mebarki, A.

Abstract

This paper deals with the stochastic seismic analysis of a site in the city of Algiers (Algeria), which is composed by superposed layers over an elastic halfspace. Layers heights are assumed to be random variables with a lognormal distribution, which is suitable for strictly non-negative random variables. The analysis is carried out via Monte Carlo simulations coupled to the stiffness matrix method. A parametric study is conducted do derive the stochastic behavior of the extreme ground acceleration, its response spectrum and the transfer function. The soil height coefficient of variation is varied from 0 (corresponding to the homogeneous case) to 0.5. The input seismic acceleration corresponds to Boumerdes earthquake (Algeria, May 21st, Mw=6.5). Layers height variability causes an increase of the NS component of the peak ground acceleration and a decrease of the EW component. The soil profile height heterogeneity affects the form of the PGA but slightly its amplitude. This variability induces a slight increase of the soil profile fundamental frequency and an extension of the frequency content, indicating that the resonance phenomenon concerns a larger number of structures. The soils height randomness acts as the variation of the incident angle: decreasing the amplitude and shifting of the resonant frequencies. The maximum values of the confidence interval of the transfer function, for both mean and standard deviation, correspond to eigenfrequencies, which implies that the uncertainty is amplified by the resonance phenomenon.

3. Lymphoproliferative syndrome with autoimmunity: A possible genetic basis for dominant expression of the clinical manifestations.

Author

Rieux-Laucat F, Blachère S, Danielan S, De Villartay JP, Oleastro M, Solary E, Bader-Meunier B, Arkwright P, Pondaré C, Bernaudin F, Chapel H, Nielsen S, Berrah M, Fischer A, and Le Deist F

Subjects
Adolescent, Adult, Age Factors, Amino Acid Substitution, Apoptosis, Autoimmune Diseases immunology, Child, Exons genetics, Female, Follow-Up Studies, Genes, Dominant, Genetic Heterogeneity, Genetic Predisposition to Disease, Heterozygote, Humans, Hypergammaglobulinemia etiology, Hypersplenism etiology, Hypersplenism surgery, Infant, Lymphoproliferative Disorders immunology, Male, Point Mutation, Splenectomy, Splenomegaly etiology, Splenomegaly surgery, T-Lymphocytes chemistry, T-Lymphocytes pathology, Uveitis etiology, Autoimmune Diseases genetics, Lymphoproliferative Disorders genetics, fas Receptor genetics
Abstract

Fas (CD95/Apo-1) mutations were previously reported as the genetic defect responsible for human lymphoproliferative syndrome associated with autoimmune manifestations (also known as autoimmune lymphoproliferative syndrome or Canale-Smith syndrome). We have identified 14 new heterozygous Fas mutations. Analysis of patients and families allow us to further dissect this syndrome with regards to the relationship between Fas mutations, inheritance pattern, and phenotype as observed on long-term follow-up. In vitro studies show that lymphocytes from all Fas mutant carriers exhibit a Fas-antibody-induced apoptosis defect. However, among the 8 inherited mutations, 4 of 4 Fas missense mutations were associated with high clinical penetrance, whereas 3 of 4 mutations leading to a truncated Fas product were associated with variable clinical penetrance. This suggests that a second defect, in another yet undefined factor involved in apoptosis and/or lymphoproliferation control, is necessary to induce full clinical expression of the disease. These results also indicate that the currently available antibody-mediated in vitro apoptosis assay does not necessarily reflect the in vivo ability of abnormal Fas molecules to trigger lymphocyte death. In addition, we found that lymphoproliferative manifestations resolved with age, whereas immunological disorders [ie, hypergammaglobulinemia and detection of TcR alphabeta(+) CD4(-) CD8(-) lymphocytes] persisted. This observation suggests that Fas-mediated apoptosis plays a more important role in lymphocyte homeostasis in early childhood than later on in life.

Published
1999

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