We report a patient with Guillain–Barré syndrome (GBS), characterized by severe tetraparesis, bulbar syndrome, and ophthalmoparesis. The nadir was reached within 1 day, followed by respiratory insufficiency requiring mechanical ventilation. Molecular analysis revealed a duplication at chromosome 17p11.2‐12, which is a known genetic cause of Charcot–Marie–Tooth disease type 1A (CMT1A). We suggest that this genotype may comprise a previously unrecognized genetic risk factor for GBS. Muscle Nerve, 2007

Roberts syndrome/SC phocomelia (RBS) is an autosomal recessive disorder with growth retardation, craniofacial abnormalities and limb reduction. Cellular alterations in RBS include lack of cohesion at the heterochromatic regions around centromeres and the long arm of the Y chromosome, reduced growth capacity, and hypersensitivity to DNA damaging agents. RBS is caused by mutations in ESCO2, which encodes a protein belonging to the highly conserved Eco1/Ctf7 family of acetyltransferases that is involved in regulating sister chromatid cohesion. We identified 10 new mutations expanding the number to 26 known ESCO2 mutations. We observed that these mutations result in complete or partial loss of the acetyltransferase domain except for the only missense mutation that occurs in this domain (c.1615T>G, W539G). To investigate the mechanism underlying RBS, we analyzed ESCO2 mutations for their effect on enzymatic activity and cellular phenotype. We found that ESCO2 W539G results in loss of autoacetyltransferase activity. The cellular phenotype produced by this mutation causes cohesion defects, proliferation capacity reduction and mitomycin C sensitivity equivalent to those produced by frameshift and nonsense mutations associated with decreased levels of mRNA and absence of protein. We found decreased proliferation capacity in RBS cell lines associated with cell death, but not with increased cell cycle duration, which could be a factor in the development of phocomelia and cleft palate in RBS. In summary, we provide the first evidence that loss of acetyltransferase activity contributes to the pathogenesis of RBS, underscoring the essential role of the enzymatic activity of the Eco1p family of proteins.

RNA-binding proteins are involved in post-transcriptional processes like mRNA stabilization, alternative splicing, and transport. Brunol1 is a novel mouse gene related to elav/Bruno family of genes encoding for RNA-binding proteins. We report here the expression and functional analysis of murine Brunol1. Expression analysis of Brunol1 during embryogenesis by RT-PCR showed that Brunol1 expression starts at 9.5 dpc and continues to the later stages of embryonic development. In adult mice, the Brunol1 expression is restricted to brain and testis. We also analyzed the Brunol1 expression in testes of different mutants with spermatogenesis defects: W/W(V), Tfm/y, Leyl(-/-), olt/olt, and qk/qk. Brunol1 transcript was detectable in Leyl(-/-), olt/olt, and qk/qk mutant but not in W/W(V) and Tfm/y mutants. We also showed by transfection of a fusion protein of green fluorescent protein and Brunol1 protein into NIH3T3 cells, that Brunol1 is localized in cytoplasm and nucleus. In order to elucidate the function of the Brunol1 protein in spermatogenesis, we disrupted the Brunol1 locus in mouse by homologous recombination, which resulted in a complete loss of the Brunol1 transcript. Male and female Brunol1(+/-) and Brunol1(-/-) mice from genetic backgrounds C57BL/6J x 129/Sv hybrid and 129X1/SvJ when inbred exhibited normal phenotype and are fertile, although the number and motility of sperms are significantly reduced. An intensive phenotypic analysis showed no gross abnormalities in testis morphology. Collectively our results demonstrate that Brunol1 might be nonessential protein for mouse embryonic development and spermatogenesis.

BACKGROUND:Charcot-Marie-Tooth neuropathies are a group of genetically heterogeneous diseases of the peripheral nervous system. Mutations in the MFN2 gene have been reported as the primary cause of Charcot-Marie-Tooth disease type 2A.METHODS:Patients with the clinical diagnosis of Charcot-Marie-Tooth type 2 were screened using single strand conformation polymorphism (SSCP). All DNA samples showing band shifts in the SSCP analysis were amplified from genomic DNA and cycle sequenced.RESULTS:We analyzed a total of 73 unrelated patients with a clinical diagnosis of CMT 2. Overall, novel mutations were detected in 6 patients. c.380G>T (G127V), c.1128G>A (M376I), c.1040A>T (E347V), c.1403G>A (R468H), c.2113G>A (V705I), and c.2258_2259insT (L753fs).CONCLUSION:We confirmed a significant role of mutations in MFN2 in the pathogenesis of Charcot-Marie-Tooth disease type 2.

Electrophoretic separation of nucleic acids according to their molecular weights has dominated the methods' spectrum in molecular genetics for nearly half a century. We review the current methodological basis and evaluate its impact with special reference to new developments in the microarray technology. Although electrophoresis may be made redundant for many applications in DNA diagnostics within a few years, a number of electrophoretic vestiges will remain irreplaceable in the foreseeable future.

Alexander disease (AD) is a rare genetic disorder of the central nervous system due to a dysfunction of astrocytes. The most common infantile form presents as a progressive leukodystrophy with macrocephalus. Recently, heterozygous de novo mutations in the gene encoding glial fibrillary acidic protein (GFAP) have been demonstrated to be associated with AD. We used localized proton magnetic resonance spectroscopy (MRS) to assess metabolic abnormalities in grey and white matter, basal ganglia, and cerebellum of 4 patients with infantile AD and GFAP mutations. Strongly elevated concentrations of myo-inositol in conjunction with normal or increased choline-containing compounds in all regions investigated point to astrocytosis and demyelination. Neuroaxonal degeneration, as reflected by a reduction of N-acetylaspartate, was most pronounced in cerebral and cerebellar white matter. The accumulation of lactate in affected white matter is in line with infiltrating macrophages. Metabolic alterations demonstrated by in vivo proton MRS are in excellent agreement with known neuropathological features of AD.

Mutations in the connexin 26 gene (GJB2) are responsible for the major part of nonsyndromic autosomal recessive or apparently sporadic prelingual deafness in Caucasians (DFNB1). We screened 228 German hearing-impaired persons for mutations in the GJB2 gene by sequence analysis. Homozygous or compound heterozygous GJB2 mutations were detected in 38/228 (16.7%) of hearing impaired persons. The most frequently occurring mutation was the c.35delG mutation, which was found in 71.1% of the mutated alleles. The next frequent mutation detected in the group of hearing impaired persons was the c.101T>C mutation (9/76 alleles; 11.8%). One new mutation, c.567delA, was observed. We further studied the presence of a 10bp deletion in the 5' UTR of the GJB2 gene (c.-493del10) which was assumed to occur together with the c.101T>C mutation. Ten out of thirteen patients (76.9%) were found to be carriers of both the c.101T>C mutation and the 10bp variant and in 7/14 alleles a linkage disequilibrium between c.101T>C and the 10bp deletion was proven. In 4/14 alleles the linkage was ruled out and for the remaining 3 cases the phase determination was not possible. Seventy one controls were screened for the prevalence of Cx26 mutations and for the c.-493del10 variant. Heterozygosity frequency in the control group was for c.35delG 4.2%, for c.101T>C 1.4% and for c.-493del10 it was 5.6%.

T-box transcription factors contain a novel type of DNA-binding domain, the T-box domain, and are encoded by an ancient gene family. Four T-box genes, omb, Trg, org-1, and H15, have been identified in Drosophila, whereas in mammals the T-box gene family has expanded, and 12 human T-box genes have been isolated. We have identified a new human T-box gene, TBX20, and its mouse homologue Tbx20, which are more closely related to the Drosophila H15 gene than to any known vertebrate gene. H15 expression in leg imaginal discs correlates with commitment to a ventral fate, implicating this gene in early patterning events. We find that TBX20 is expressed in the fetal heart, eye, and limb, and during embryogenesis in the mouse, Tbx20 is expressed in the developing heart, eye, ventral neural tube, and limbs, indicating a possible role in regulating development of these tissues. The TBX20 gene maps to chromosome 7p14–p15. An association between TBX20 and loci for retinitis pigmentosa, RP9, and blepharophimosis syndrome, BPES, have been excluded.

BACKGROUND:Lattice corneal dystrophy type I is one of the frequent forms of stromal dystrophies following autosomal dominant inheritance. The beta-IG-h3 gene encoding keratoepithelin on the long arm of chromosome 5 has recently been described as disease gene for lattice corneal dystrophy type I as well as for three other corneal dystrophies with autosomal dominant pattern of inheritance. PATIENTS AND METHODS:Ten family members in three generations of a large family with autosomal dominant lattice corneal dystrophy were analyzed clinically by slit-lamp biomicroscopy. Mutation analysis in the beta-IG-h3 gene was carried out at the mRNA level by RT-PCR and cDNA sequencing. RESULTS:A heterozygous single-base substitution (417C-->T) in exon 4 of the beta-IG-h3 gene was detected predicting the replacement of arginine-124 by cysteine. Analysis of 10 family members showed perfect cosegregation of the mutation and lattice corneal dystrophy type I. The investigation excluded this mutation in one family member previously classified as potentially affected. CONCLUSIONS:The investigation confirmed autosomal dominant inheritance with complete penetrance in the family described. The mutation 417C-->T has already been found earlier in another family of different geographic origin. These results suggest a mutation hot spot at position 417. In addition, no evidence of genetic heterogeneity of lattice corneal dystrophy type I was detected. Molecular genetic analysis (in conjunction with genetic counselling) therefore may be useful in routine diagnostics as the confirmation of the diagnosis by histological examination is possible only after keratoplasty. The common pathomechanism in lattice corneal dystrophy type I may facilitate development of new therapeutic concepts; the easy accessibility of the target organ may provide new possibilities e.g. for gene therapy.