Recessive Schwartz-Jampel syndrome (SJS): confirmation of linkage to chromosome 1p, evidence of genetic homogeneity and reduction of the SJS locus to a 3-cM interval.

Schwartz-Jampel syndrome (SJS), or chondrodystrophic myotonia, is a rare autosomal recessive disorder characterized by generalized myotonia resulting in a particular, recognizable facies and osteoarticular abnormalities. Some of us have recently shown genetic linkage of SJS to a locus on 1p34-p36.1 in five families. Here, we show by homozygosity mapping and segregation analysis that eight new families are most likely linked to the SJS locus on chromosome 1, confirming the localization of SJS to chromosome 1p and suggesting genetic homogeneity. Recombination events reduced the SJS locus from a genetic interval of 8 to 3 cM, which should facilitate the identification of the SJS gene. Low clinical variability was observed between the studied families, except for osteoarticular abnormalities. Since the severity and the location of osteoarticular abnormalities varied from one individual to another, even in the same families, other factors than the SJS gene itself, genetic or epigenetic, might contribute to the phenotype.

Localization of the Schwartz-Jampel syndrome (SJS) locus to chromosome 1p34-p36.1 by homozygosity mapping.

Schwartz-Jampel syndrome (SJS, MIM 255800), also known as chondrodystrophic myotonia, is a rare autosomal recessive disorder characterized by generalized myotonia, skeletal abnormalities and facial dysmorphism. Using homozygosity mapping, we localized the SJS locus to chromosome 1p34-p36.1 in a 8 cM interval flanked by markers D1S199 and D1S234. Families of different ethnic backgrounds (Tunisia and South Africa) showed genetic linkage to the same locus. Moreover, one Algerian family also demonstrated evidence of genetic linkage to 1p34-p36.1. Taken altogether, our results suggest genetic homogeneity, at least in the group of families analyzed.

[Acute respiratory infections of viral origin in the children of Algiers, Algeria based on a seroepidemiological study]. / Les infections respiratoires aiguës d'origine virale chez les enfants à Alger--Algérie, à travers une étude séro-épidémiologique.

401 double serum samples from 0 to 14 year old children with acute respiratory diseases (ARD) were analysed in view to establish the viral etiology. 198 (49.4%) out of the 401 were positive. The syncytial respiratory virus (SRV) was the most frequent (29.8%) among the positives, followed by the parainfluenzae virus type 3 (24.7), the influenza A virus (23.7%), the parainfluenzae type 1 (8.5%), the influenza B (7%) and the parainfluenza type 2 (2%). Seven samples out of 109 were positive for adenovirus. The SRV infections were very frequent before one year of age and after six. The parainfluenza virus type 3 was found mostly during the second year of life and was different in this from the types 1 and 2 prevalent after the age of six. The SRV is responsible for subglottic ARD (73%), as well as the parainfluenza virus type 3 (68.5%), the influenza virus types A (69%) and B (61.5%). On the contrary, the parainfluenza viruses types 1 (70%) and 2 (67%) attacked especially the upper respiratory tract. Studies were also worked out on the effects of season, sex, antibiotherapy, as well as on the viruses most incriminated in hospitalization.

Rapid diagnosis of respiratory syncytial virus infection by antigen immunofluorescence detection with monoclonal antibodies and immunoglobulin M immunofluorescence test.

During a respiratory syncytial virus (RSV) infection outbreak in a pediatric hospital, diagnosis was made by immunofluorescence on smears by using an anti-RSV monoclonal antibody (IFm). Immunoglobulins M and G were titrated by indirect immunofluorescence on HEp-2 cells infected with an RSV strain. The IFm was sensitive (89%) and specific (75%) when compared with the cell culture method. We showed that the specimens which were found positive by IFm and negative by cell culture were truly positive. Under these conditions, the IFm test appears more sensitive and more specific than cell culture, particularly when no care is taken to maintain the specimens in the cold during transport. In this study the immunoglobulin M immunofluorescence test had a low sensitivity (34%), especially on serum samples taken on days 0 to 4 after the onset of illness.

[Prenatal diagnosis of generalized cytochrome b5 reductase deficiency (congenital methemoglobinemia with mental retardation, type II) (author's transl)]. / Diagnostic prénatal du déficit généralisé en cytochrome b5 réductase (méthémoglobinémie congénitale récesive de type II avec encéphalopathie).

Two first cases of prenatal diagnosis of generalized cytochrome b5 reductase deficiency are presented. In each family, there was an index case with a clinical pattern of congenital methemoglobinemia associated with severe mental retardation (type II). The foetal cells were obtained by amniocentesis at 16 weeks of pregnancy at risk. The cells were cultured, and their cytochrome b5 reductase activity was compared to control amniotic cells, and to cultured fibroblasts originating from the index case. In the first family this led to the conclusion that the foetus was normal or heterozygous. The pregnancy was continued, and the mother delivered a normal newborn with normal red-cell cytochrome b5 reductase. In the second family, the foetal cells displayed a profound decrease of cytochrome b5 reductase activity. The pregnancy was terminated and all the tissues of the aborted foetus exhibited the enzyme deficiency. It is concluded that prenatal diagnosis of the severe form of congenital methemoglobinemia can be performed without ambiguity.