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Follow-up and re-evaluation of four patients originally described as examples of severe infantile "micromelic chondrodysplasia" resembling Kniest disease, "kyphomelic dysplasia," and "Burton skeletal dysplasia" revealed the diagnosis of Schwartz-Jampel syndrome (SJS, myotonic chondrodysplasia) in all of them. SJS may be suspected in neonates with Kniest-like chondrodysplasia, congenital bowing of shortened femora and tibiae, and facial manifestations consisting of a small mouth, micrognathia, and possibly pursed lips. The disorder must be differentiated from the Stüve-Wiedemann syndrome, a genetically distinct myotonic chondrodysplasia with similar clinical but different skeletal changes and an unfavorable early prognosis. The demise of "kyphomelic dysplasia" as a nosological entity reemphasizes the symptomatic nature of congenital bowing of the long bones.

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PURPOSE: To report a case of tumor like amyloïd formation (amyloidoma) of the brain with etiologic discussion. MATERIAL: and Methods. A 46-year-old female had a 7 year history of epilepsy. CT scan and MRI revealed two enhancing lesions in the white matter of the right temporal and frontal lobes. RESULTS: Stereotactic biopsy examination showed large amyloid deposits surrounded by sparsely scattered lymphocytes, few matures plasma cells, macrophages and rare foreign body type giant cells. The congophilic amyloid was found in the interstitium as well as within the walls of blood vessels with close connection to the choroid plexus. No significant abnormalities were noted on routine laboratory studies. DISCUSSION: Unlike all other types of amyloid, AL amyloid can produce both systemic amyloidosis and solitary amyloidoma. Amyloidomas are rare and usually found in the lung, skin, lower urinary tract. The location in the brain is extremely rare, with only 16 cases reported in the literature. All this cases as well as our example in the current study to some extent involved deep white matter. The association with choroid plexus is possible. The relatively indolent course of this amyloidomas is noted. Our study showed a presence of monotypic lambda producing plasma cells. Thus this lesion could be the result of monoclonal B cell neoplasm capable of terminal differentiation and the existence of AL amyloid producing low grade B lymphomas of the brain could be discussed.

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A novel human gene, TRPC5, was cloned from the region of Xq23 that contains loci for nonsyndromic mental retardation (MRX47 and MRX35) and two genes, DCX and HPAK3, implicated in two X-linked disorders (LISX and MRX30). Within a single YAC, we have determined the order cen-HPAK3(5'-3')-DCX(3'-5')-DXS7012E-TRPC5(3'-5' )-ter. TRPC5 encodes a 974-residue novel human protein (111.5 kDa predicted mass) and displays 99% homology with mouse TRP5, (MGD-approved symbol Trrp5) a novel member of a family of receptor-activated Ca2+ channels. It contains eight transmembrane domains, including a putative pore region. A transcript larger than 9.5 kb is observed only in fetal and adult human brain, with a relatively higher level in the adult human cerebellum. We devised an efficient method, Incorporation PCR SSCP (IPS), for detection of gene alterations. Five single-nucleotide variations in the TRPC5 gene were identified in males with mental retardation. However, these were found to be polymorphic variants. Exclusive expression of the TRPC5 gene in developing and adult brain suggests a possible role during development and provides a candidate gene for instances of mental retardation and other developmental defects.

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X-linked myotubular myopathy (XLMTM; OMIM310400) is a congenital muscle disorder characterized by severe hypotonia and respiratory insufficiency. The disorder was mapped to Xq28 by linkage studies and the MTM1 gene was isolated by positional cloning. The gene product is a 603 amino acid protein named myotubularin. A small domain in its sequence shows high homology to a consensus active site of tyrosine phosphatases, a diverse class of proteins involved in signal transduction, control of cell growth, and differentiation. In this report, two brothers affected with XLMTM are shown to have a point mutation (G1187A) in exon 11 of the MTM1 gene. Surprisingly, their mother does not have this mutation in her lymphocytes. Therefore, she likely has a germline mosaicism. As this is the third report of germline mosaicism in XLMTM, the finding has important implications for genetic counseling.

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Of the gene-rich regions of the human genome, Xq28 is the most densely mapped. Mutations of genes in this band are responsible for 10 syndromal forms of mental retardation and 5 nonsyndromal forms. Clinical and molecular studies reported here add an additional syndromic form of X-linked mental retardation (XLMR) to this region. The condition comprises short stature, small hands and feet, seizures, cleft palate, and glaucoma. One affected male died at age 19 years in status epilepticus, but others have survived to old age. Carrier females do not have somatic anomalies or mental impairment. The gene is localized to the terminal 8 Mb of Xq28 with markers distal to DXS8011 showing linkage to the disorder with a lod score of 2.11 at zero recombination.

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We studied a family with 11 males having X-linked mental retardation (XLMR) using microsatellite markers. Aside from the mental retardation, the affected males do not appear to differ from their unaffected brothers or uncles. The gene for this XLMR condition has been linked to DXS451 in Xp22.13 with a lod score of 5.18 at straight theta = 0. Recombination was detected at DXS992 (Xp21.3) and DXS1053 (Xp22.2), thereby defining the limits of the localization. This family is considered to have nonsyndromic XLMR and has been assigned the designation MRX32.

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Efforts to understand the genetic basis of mental retardation are greatly assisted by the identification of families with multiple relatives with mental retardation that clinical geneticists encounter in the routine practice of their profession. Here we describe a linkage study of a four generation family in which X linked recessive mental retardation (XLMR) is associated with minor dysmorphism and premature death of the affected males. Microsatellite based polymorphic loci evenly spaced over the entire X chromosome were used initially to detect linkage to Xq28. Further analysis identified a haplotype of Xq28 markers bounded proximally by locus DXS1113 and distally by DXS1108 that cosegregated with XLMR in this family. Two point lod scores > 3.0 provided strong evidence that the gene locus responsible for XLMR in this family is within this 7 Mb region of Xq28. The minor anomalies noted in some affected males were not distinctive enough to suggest a unique syndrome. None of our patients had features of the Waisman-Laxova syndrome or the PPM-X syndrome. The possibility of allelism with any of the five other non-specific XLMR syndromes (MRX3, MRX16, MRX25, MRX28, and MRX41) mapped to Xq28 could not be excluded. While the recognition of a gene responsible for this disorder needs much additional work, multiple female relatives at risk in this family benefit immediately from knowing their genotype and heterozygotes will have the opportunity to undergo prenatal diagnosis.

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A syndrome with distinctive facies, poor muscle tone, absent deep tendon reflexes, tapered fingers, excessive fingerprint arches, genu valgum and mild-moderate mental retardation has occurred in four males in two generations of a white family of European ancestry. The facies are characterised by square configuration, tented upper lip, and thickening of the helices, upper eyelids, and alae nasi. At birth and at maturity, growth (head circumference, height, weight) of affected males is comparable to or greater than unaffected male sibs. Moderate impairment of cognitive function was documented (IQ scores between 40-51). Carriers show no heterozygote manifestations. This X linked condition appears to be different from other syndromes with mental retardation, although there are certain similarities with the alpha thalassaemia-mental retardation syndrome (ATR-X). Linkage analysis found tight linkage to DXS1166 and DXS995 in Xq13 and Xq21 respectively.

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The gene responsible for nonsyndromic mental retardation in a family with 7 affected males has been localized to Xp21. The maximal two-point lod score was 3.31 for tight linkage to marker DXS1202 in Xp21.3-p22.3 with crossovers between the 3' portion of the DMD gene (DXS1234) proximally and locus DXS989 distally. The XLMR gene in this family has been assigned the designation MRX29. The localization overlaps with at least six other MRX entities linked to the distal short arm of the X chromosome.

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Permanently established human cell lines can produce several retroviruses. It is important to routinely test such cell lines for human T cell lymphotropic virus (HTLV) type I and II, and for human immunodeficiency virus (HIV) type 1 and 2 in order to exclude any potential biohazard from cell lines producing human retroviruses. Reverse transcriptase assay, polymerase chain reaction, and dot-blot hybridization of in-vitro amplified DNA with virus-specific probes are used.

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A database of DNA fingerprint profiles from permanently established human and animal cell lines was prepared with a computer program originally designed for numerical taxonomy of bacteria. Identifications of cell line DNA profiles were performed, both by the Pearson product-moment correlation coefficient and by band matching. Under the conditions used the Pearson product-moment correlation coefficient was consistently more reliable.

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The genetic stability of human cell lines in long-term culture has been tested by DNA fingerprinting a panel of 31 different continuous cell lines from patients with leukemias or lymphomas. Duplicates of the same cell line obtained from different sources, subclones of cell lines, and samples of cell lines at different passage levels were studied. In most cases the fingerprints of duplicates of the same cell line remained perfectly preserved even after long-time passaging. However, in five cases there were notable differences between individual fragments of corresponding fingerprints. We have found four cases of mislabeled and/or cross-contaminated cell lines so far. Taken together, our results indicate that DNA fingerprinting qualifies as a very reliable means of cell line identification which allows the detection of mislabelling or contamination and of genetic variation among subclones.

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The infection of cell lines with mycoplasma can cause severe problems as the contaminants affect virtually every cell parameter. We attempted to eliminate mycoplasma from contaminated cell lines using the fluoroquinolone antibiotic ciprofloxacin. Mycoplasma-infected cell lines were cultured with 10 micrograms/ml ciprofloxacin for 14 days. The elimination or persistence of mycoplasmal infection was monitored by diamidino-2-phenylindole (DAP) DNA staining, RNA hybridization test and broth-agar microbiological culturing. Seventeen out of 21 positive cell lines (81%) have been successfully treated using ciprofloxacin. Mycoplasma infections are unacceptable in experimental in vitro systems and require an elimination procedure of certain efficiency. The use of adequate detection methods in the routine control of cell lines and the avoidance of emerging resistant strains are of the utmost importance.

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A human c-sis cDNA in an expression vector was introduced into human diploid fibroblasts by transfection or electroporation. Fibroblast clones showing an aberrant, densely packed colony morphology were isolated and found to overexpress a 3.6-kilobase sis mRNA species and associated immunoprecipitable platelet-derived growth factor (PDGF) 2 proteins. Parallel analyses in cell clones of sis mRNA expression and colony formation in agar indicated that, above a threshold, a linear, positive correlation existed between sis overexpression and acquired anchorage independence. The sis-overexpressing cells formed transient, regressing tumor nodules when injected into nude mice, consistent with the finite life span which they retained. Protein products generated from the transfected c-sis construct in two overexpressing clones were immunoprecipitated with anti-human PDGF antibodies. One clone contained an apparent PDGF dimer of 21 kilodaltons; the second clone contained only an apparent PDGF monomer of 12 kilodaltons, which was shown to account for all of the mitogenic activity present in the cells, essentially all of which was concentrated in the membrane fraction. The results demonstrate a clear link between sis overexpression and acquisition of a partially transformed, anchorage-independent phenotype, and when combined with previous observations of sis overexpression in human tumors, clearly implicate sis overexpression as a genetic mechanism which contributes to human cell transformation.

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