[A new gene locus for an autosomal-dominant non-syndromic hearing impairment (DFNA 33) is situated on chromosome 13q34-qter]. / Ein neuer Genort für eine autosomal-dominante, nichtsyndromale Schwerhörigkeit (DFNA33) liegt auf Chromosom 13q34-qter.

By investigation of a German family pedigree with non-syndromic hearing impairment of early onset and autosomal-dominant mode of inheritance, linkage to known DFNA loci was excluded, and the existence of a new locus (DFNA33) was revealed. In a subsequent genomic scan the phenotype was mapped to a 6 cM interval on chromosome 13q34-qter. A maximum two-point lod score of 2.96 was obtained for the marker D13S285 with a maximum lod score in the multipoint analysis of 3.28 at 124.56 cM.

[A new locus for an autosomal dominant, non-syndromic hearing impairment (DFNA57) located on chromosome 19p13.2 and overlapping with DFNB15]. / Ein neuer Genort für eine autosomal dominante, nichtsyndromale Hörstörung (DFNA57) kartiert auf Chromosom 19p13.2 und überlappt mit DFNB15.

BACKGROUND: Non-syndromic hearing loss is the most genetically heterogeneous trait known in humans. To date, 54 loci for autosomal dominant non-syndromic sensorineural hearing loss (NSSHL) have been identified by linkage analysis. METHODS: In this study a German pedigree has been identified segregating a progressive bilateral loss of lower and middle frequencies. RESULTS: A genome-wide screening and linkage analysis revealed the existence of a new NSSHL locus (DFNA57). The phenotype was mapped to a 10 degrees Mbp interval on chromosome 19p13.2 from 7.8 to 18.2 degrees Mbp, a maximum 2-point LOD score of 3.08 was obtained for the marker D19S586. The region overlaps with the recessive locus DFNB15. CONCLUSION: The results underline the heterogeneity of hereditary hearing disorders. Identification of genes can help to reach a better understanding of the molecular mechanism of hearing.

Dopamine and N-methyl-D-aspartate receptor expression in peripheral blood of patients undergoing alcohol withdrawal.

The aim of the present pilot study was to explore whether a change in cerebral receptors can be demonstrated in human peripheral blood lymphocytes during alcohol withdrawal. Dopamine (D1 and D2) and NMDA (1 and 2B) receptor expressions of 14 male patients suffering from alcohol-dependency were assessed through quantitative RT-PCR. A significant difference in D1 receptor expression (T = 2.361; p = 0.035) in terms of up-regulation could be shown, though there were no significant changes concerning D2, NMDA1 or NMDA2B receptor expression.

Lowered DNA methyltransferase (DNMT-3b) mRNA expression is associated with genomic DNA hypermethylation in patients with chronic alcoholism.

DNA methyltransferases (DNMTs) are involved within the epigenetic control of DNA methylation processes. Recently, it has been shown that the genomic DNA methylation in patients with alcoholism is increased. In the present controlled study we observed a significant decrease of mRNA expression of DNMT-3a and DNMT-3b when comparing alcoholic patients (n = 59) with healthy controls (n = 66): DNMT-3a (t = -2.38, p = 0.019), DNMT-3b (t = -2.65, p = 0.008). No significant differences were seen for DNMT-1 and Mbd-2 (Methyl-CpG-Binding-Domain protein 2) expression. Additionally, we observed a significant negative correlation between DNMT-3b expression and the blood alcohol concentration (r = -0.45, p = 0.003) which might explain the decrease of DNMT-3b mRNA expression in alcoholic patients. Using a multivariate model we observed that the increase (10%) of genomic DNA methylation in patients with alcoholism was significantly associated with their lowered DNMT-3b mRNA expression (multiple linear regression, p = 0.014). Since methylation of DNA is an important epigenetic factor in regulation of gene expression these findings may have important implications for a possible subsequent derangement of epigenetic control in these patients.

Cognitive impairment and its association with homocysteine plasma levels in females with eating disorders - findings from the HEaD-study.

Higher plasma homocysteine levels have been found in females with anorexia nervosa. Furthermore, elevated homocysteine levels are associated with cognitive decline in dementia and healthy elderly people. Aim of this prospective study was to investigate a possible association between homocysteine serum levels and Clinically well known cognitive deficits in females with eating disorders. We found that moderately elevated plasma homocysteine levels were associated with normal short- and long-term verbal memory while normal plasma homocysteine levels were associated with poorer memory performance in 14 females with anorexia nervosa and 12 females with bulimia nervosa (logistic forward regression Wald chi(2)=8.566, OR=24.75, CI 2.89 - 212.23, P=0.003). These results indicate that under the special circumstances of eating disorders elevated homocysteine levels improve memory signaling possibly by facilitating long-term potentiation.

Homocysteine plasma levels are elevated in females with anorexia nervosa.

In the present pilot study significantly (T = 2.46, P = 0.018) higher levels of homocysteine were found in female anorectic patients (14.07, SD 7.3 micromol/l; n = 18) when compared with bulimic patients (10.25, SD 2.82; n = 27) or healthy controls (8.10, SD 1.79; n = 25). Since homocysteine can induce neuronal cell death leading to brain atrophy in different diseases and since it has been linked to depressive disorders these findings may have important implications for understanding common symptoms in patients suffering from anorexia.

Joint analysis of the NACP-REP1 marker within the alpha synuclein gene concludes association with alcohol dependence.

Various studies have linked alcohol dependence phenotypes to chromosome 4. One candidate gene is NACP (non-amyloid component of plaques), coding for alpha synuclein. Recently, it has been shown that alpha synuclein mRNA is increased in alcohol-dependent patients within withdrawal state. This increase is significantly associated with craving, especially obsessive craving. On the basis of these observations, the present study analysed two polymorphic repeats within the NACP gene. We found highly significant longer alleles of NACP-REP1 in alcohol-dependent patients compared with healthy controls (Kruskal-Wallis test, chi(2)=99.5; df=3, P<0.001). In addition, these lengths significantly correlate with levels of expressed alpha synuclein mRNA (chi(2)=8.83; df=2, P=0.012). The present results point to a novel approach for a genetic determination of craving, a key factor in the genesis and maintenance not only of alcoholism but also of addiction in general.

Homocysteine associated genomic DNA hypermethylation in patients with chronic alcoholism.

Higher plasma homocysteine concentrations can influence genomic DNA methylation in peripheral blood cells. In the present controlled study we observed a significant increase (10%) of genomic DNA methylation in patients with alcoholism (t = -3.16, df = 158, p = 0.002) which was significantly associated with their elevated homocysteine levels (multiple linear regression, p < 0.001). Since methylation of DNA is an important epigenetic factor in regulation of gene expression these findings may have important implications for a possible subsequent derangement of epigenetic control these patients.

Motor system abnormalities in hereditary spastic paraparesis type 4 (SPG4) depend on the type of mutation in the spastin gene.

BACKGROUND: Hereditary spastic paraparesis (HSP) denotes a group of inherited neurological disorders with progressive lower limb spasticity as their clinical hallmark; a large proportion of autosomal dominant HSP belongs to HSP type 4, which has been linked to the SPG4 locus on chromosome 2. A variety of mutations have been identified within the SPG4 gene product, spastin. OBJECTIVE: Correlation of genotype and electrophysiological phenotype. MATERIAL: Two large families with HSP linked to the SPG4 locus with a very similar disease with respect to age of onset, progression, and severity of symptoms. METHODS: Mutation analysis was performed by PCR from genomic DNA and cDNA, and direct sequencing. The motor system was evaluated using transcranial magnetic stimulation. RESULTS: Patients differ in several categories depending on the type of mutation present. CONCLUSIONS: For the first time in hereditary spastic paraparesis, a phenotypic correlate of a given genetic change in the spastin gene has been shown.

Mutation analysis of the spastin gene (SPG4) in patients in Germany with autosomal dominant hereditary spastic paraplegia.

Hereditary spastic paraplegias (HSP) comprise a genetically and clinically heterogeneous group of neurodegenerative disorders characterized by progressive spasticity and hyperreflexia of the lower limbs. Autosomal dominant hereditary spastic paraplegia 4 linked to chromosome 2p (SPG4) is the most common form of autosomal dominant hereditary spastic paraplegia. It is caused by mutations in the SPG4 gene encoding spastin, a member of the AAA protein family of ATPases. In this study the spastin gene of HSP patients from 161 apparently unrelated families in Germany was analyzed. The authors identified mutations in 27 out of the 161 HSP families; 23 of these mutations have not been described before and only one mutation was found in two families. Among the detected mutations are 14 frameshift, four nonsense, and four missense mutations, one large deletion spanning several exons, as well as four mutations that affect splicing. Most of the novel mutations are located in the conserved AAA cassette-encoding region of the spastin gene. The relative frequency of spastin gene mutations in an unselected group of German HSP patients is approximately 17%. Frameshift mutations account for the majority of SPG4 mutations in this population. The proportion of splice mutations is considerably lower than reported elsewhere.

Drug-induced nonconvulsive status epilepticus with low dose of tiagabine.

In placebo-controlled trials, the overall incidence of nonconvulsive status epilepticus was no higher in the tiagabine-treated group than in the placebo-group. Case reports of nonconvulsive status epilepticus under tiagabine suggested a specific role of dose levels, since in these patients symptoms occurred mostly at 40 mg/day or higher. We report a case of complex partial status epilepticus in a patient receiving a low dose of tiagabine and review all 11 case reports of nonconvulsive status epilepticus in patients on tiagabine, with regard to daily doses. Our analysis suggests an individual risk threshold of unknown aetiology.

A novel locus for autosomal dominant, non-syndromic hearing impairment (DFNA18) maps to chromosome 3q22 immediately adjacent to the DM2 locus.

Investigating a large German pedigree with non-syndromic hearing impairment of early onset and autosomal dominant mode of inheritance, linkage to known DFNA loci was excluded and in a subsequent genomic scan the phenotype was mapped to a 10-cM interval on chromosome 3q22; a maximum two-point lod score of 3.77 was obtained for the marker D3S1292. The new locus, DFNA18, is excluded from neighbouring deafness loci, DFNB15 and USH3, and it overlaps with the recently described DM2/PROMM locus. As hearing loss has been described as one feature of the PROMM phenotype, the DFNA18 gene might also be responsible for hearing loss in DM2/PROMM.

Spectrum of SPG4 mutations in autosomal dominant spastic paraplegia.

Autosomal dominant hereditary spastic paraplegia (AD-HSP) is a group of genetically heterogeneous neurodegenerative disorders characterized by pro- gressive spasticity of the lower limbs. Five AD-HSP loci have been mapped to chromosomes 14q, 2p, 15q, 8q and 12q. The SPG4 locus at 2p21-p22 has been shown to account for approximately 40% of all AD-HSP families. SPG4 encoding spastin, a putative nuclear AAA protein, has recently been identified. Here, sequence analysis of the 17 exons of SPG4 in 87 unrelated AD-HSP patients has resulted in the detection of 34 novel mutations. These SPG4 mutations are scattered along the coding region of the gene and include all types of DNA modification including missense (28%), nonsense (15%) and splice site point (26.5%) mutations as well as deletions (23%) and insertions (7.5%). The clinical analysis of the 238 mutation carriers revealed a high proportion of both asymptomatic carriers (14/238) and patients unaware of symptoms (45/238), and permitted the redefinition of this frequent form of AD-HSP.

A family with PROMM not linked to the recently mapped PROMM locus DM2.

Proximal myotonic myopathy is an autosomal dominantly inherited multisystem disorder, clinically similar to but genetically distinct from myotonic dystrophy (DM). A recently mapped second locus for myotonic dystrophy was thought to be an attractive candidate locus for PROMM, and this hypothesis was supported by reports of linkage to this locus in some PROMM families. We present a large German pedigree with PROMM in which linkage to this locus could be excluded, showing that PROMM is genetically heterogeneous.

Species-specific agonist/antagonist activities of human interleukin-4 variants suggest distinct ligand binding properties of human and murine common receptor gamma chain.

Interleukin-4 (IL-4) is a pleiotropic cytokine eliciting various responses in target cells upon binding to its receptor. Activation of the IL-4 receptor probably involves interaction of the ligand with both the IL-4 receptor alpha subunit (IL-4R alpha) and the common gamma chain (c gamma). Although human and murine IL-4 receptor alpha chains are specific for IL-4 from the same species, murine c gamma can form a signal-competent complex with human IL-4R alpha (hIL-4R alpha) and human IL-4 (hIL-4). We have generated a hIL-4 responsive murine myeloid cell line (FDC-4G) expressing a chimera comprising the extracellular domain of human IL-4R alpha and the intracellular domain of human granulocyte colony-stimulating factor receptor (hG-CSFR). This hybrid receptor was shown to form a complex with hIL-4 and the murine c gamma-chain. Biological activities of human IL-4 variants on murine FDC-4G cells and on the human erythroleukemic cell line TF-1 displayed a strikingly different pattern. Single amino acid replacements at two different positions in the C-terminal helix of hIL-4, the region of the previously defined "signaling site," lead to an inverse agonist/antagonist behavior of the resulting cytokines in the two cellular systems. From these findings we conclude that upon formation of the activated IL-4 receptor complex murine and human c gamma interact with hIL-4 in a geometrically different fashion.