Mapping to distal Xq28 of nonspecific X-linked mental retardation MRX72: linkage analysis and clinical findings in a three-generation Sardinian family.

Families with mentally retarded males found to be negative for FRAXA and FRAXE mutations are useful in understanding the genetic basis of X-linked mental retardation. According to the most recent data (updated to 1999), 69 MRX loci have been mapped and 6 genes cloned. Here we report on a linkage study performed on 20 subjects from a 4-generation Sardinian family segregating a non-specific X-linked recessive mental retardation (XLMR)(MRX72) associated with global delay of all psychomotor development. Five of 8 affected males have been tested for mental age, verbal and performance skills and behavioral anomalies; mental impairment ranged from mild to severe. Only minor anomalies were present in the affected subjects. Two-point linkage analysis based on 28 informative microsatellites spanning the whole X chromosome demonstrated linkage between the disorder and markers DXS1073 and F8c in Xq28 (maximum Lod score of 2. 71 at straight theta = 0.00). Multipoint linkage analysis confirmed the linkage with a Z(max) of 3.0 at straight theta = 0.00 at DXS1073 and F8c. Recombination in an affected male at DXS1073 and F8c allowed us to delimit centromerically and telomerically the region containing the putative candidate gene. The region, where MRX72 maps, overlaps that of another MRX families previously mapped to Xq28, two of which harbored mutations in GDI. Involvement of this gene was excluded in our family, suggesting another MRX might reside in Xq28.

Baccilary Angiomatosis: Negative Results Using Normal Balb/c and Balb/c Nude Mice.

Baccilary angiomatosis has recently been described as a disease that can spread systematically and that is potentially fatal. It is caused by Bartonella henselae and B. quintana, and presents as especially pronounced signs and symptoms in patients suffering from acquired immunodeficiency syndrome (AIDS). To clarify the pathogenesis of the disease and to try to define the relationships among baccilary angiomatosis, cat scratch disease and Carrión's bartonellosis, the authors of this study have attempted to develop an experimental model using mice that were immunocompetent as well as those that had their cellular immunity genetically compromised. A known concentration of B. henselae was inoculated intradermally in Balb/c an isogenic mice or an athymic group of the same lineage. Blood samples were taken on days 0, 3, 7, 10, 14, 28, and 60 after inoculation for indirect immunofluorescence antibody testing. On the 21st and 60th day, one animal from each group was sacrificed and a post mortem carried out including histological evaluation of the liver, spleen, lymph nodes, skin and other organs. Hemocultures of the sacrificed animals were collected. All results of serologic response, cultures and histologic examination were negative. The authors discuss the methodology, especially the use of isogenic animals of the same lineage in B. henselae infection, with and without immunodeficiency, and the resources for the negative results of histopathology, serology and cultures.