Jörg T. Epplen

Mutations in ENPP1 are associated with 'idiopathic' infantile arterial calcification

Idiopathic infantile arterial calcification (IIAC; OMIM 208000) is characterized by calcification of the internal elastic lamina of muscular arteries and stenosis due to myointimal proliferation. We analyzed affected individuals from 11 unrelated kindreds and found that IIAC was associated with mutations that inactivated ecto-nucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1). This cell surface enzyme generates inorganic pyrophosphate (PPi), a solute that regulates cell differentiation and serves as an essential physiologic inhibitor of calcification.

Increased susceptibility to sporadic Parkinson's disease by a certain combined α‐synuclein/apolipoprotein E genotype

Parkinsons disease (PD) is one of the most common neurodegenerative disorders affecting about 1% of Western populations older than age 50. The pathological hallmark of PD are Lewy bodies, that is, intracytoplasmic inclusion bodies in affected neurons of the substantia nigra. Recently, α‐synuclein (α‐SYN) has been identified as the main component of Lewy bodies in sporadic PD, suggesting involvement in neurodegeneration via protein accumulation. The partially overlapping pathology of PD and Alzheimers disease, as well as striking structural similarities of α‐SYN and apolipoprotein E, which is a major risk factor for late‐onset Alzheimers disease, prompted us to investigate the influence of different α‐SYN and apolipoprotein E alleles for developing sporadic PD. We performed association studies in 193 German PD patients and 200 healthy control subjects matched for age, sex, and origin. A polymorphism in the promoter region of the α‐SYN gene (NACP‐Rep1) as well as of the closely linked DNA markers D4S1647 and D4S1628 revealed significant differences in the allelic distributions between PD patients and the control group. Furthermore, the Apoε4 allele but not the Th1/E47 promoter polymorphism of the apolipoprotein E gene was significantly more frequent among early‐onset PD patients (age at onset, <50 years) than in late‐onset PD. Regarding the combination of the Apoε4 allele and allele 1 of the α‐SYN promoter polymorphism, a highly significant difference between the group of PD patients and control individuals has been found, suggesting interactions or combined actions of these proteins in the pathogenesis of sporadic PD. PD patients harboring this genotype have a 12.8‐fold increased relative risk for developing PD during their lives. Ann Neurol 1999;45:611–617

Simple repeat sequences on the human Y chromosome are equally polymorphic as their autosomal counterparts

SummaryThe human genome contains a large number of interspersed simple repeat sequences that are variable in length and can therefore serve as highly informative, polymorphic markers. Typing procedures include conventional multilocus and single locus probing, and polymerase chain reaction aided analysis. We have identified simple sequences in a cosmid clone stemming from the human Y chromosome and consisting of (gata)n repeats. We have compared these with two equivalent simple repeat loci from chromosome 12. After amplifying the tandemly repeated motifs, we detected between four and eight different alleles at each of the three loci. Codominant inheritance of the alleles was established in family studies and the informativity of the simple repeat loci was determined by typing unrelated individuals. The polymorphisms are suitable for application in linkage studies, practical forensic case work, deficiency cases in paternity determination, and for studying ethnological questions. The mutational mechanisms that bring about changes in simple repeats located both on the autosomes and on the sex chromosomes, are discussed.

DNA finger printing by oligonucleotide probes specific for simple repeats

SummaryInterspersed simple repetitive DNA is a convenient genetic marker for analysis of restriction fragment length polymorphisms (RFLPs) because of the numbers and the frequencies of its alleles. Oligonucleotide probes specific for variations of the GACTA simple repeats have been designed and hybridized to a panel of human DNAs digested with various restriction enzymes. Numerous RFLPs were demonstrated in AluI and MboI digested DNA with “pure” GATA oligonucleotides as probes. The optimal length of the probe for RFLP analysis was 20 bases taking into account fragment lengths (1.5-7 kilobases = kb), signal to background ratio, and number of clearly evaluable RFLPs. By using different restriction enzymes individual-specific hybridization patterns (“DNA fingerprints”) can be established. Hypervariable simple repeat fragments are stably inherited in a Mendelian fashion. Advantages of this method are discussed.

Submicroscopic duplication in Xq28 causes increased expression of the MECP2 gene in a boy with severe mental retardation and features of Rett syndrome

Rett syndrome is an X linked mental retardation syndrome almost exclusively affecting girls, and has long been regarded as an X linked dominant condition lethal in hemizygous males.1 Mutations in the gene encoding the methyl-CpG binding protein 2 (MECP2) were demonstrated as the cause of Rett syndrome,2 and confirmed by a number of studies. The vast majority (95%) of MECP2 mutations occurs de novo. Girls affected by “classic” Rett syndrome show mental retardation and regression, with a typical pattern of symptoms including initially normal development, stagnation, loss of acquired abilities, stereotypic hand movements, regression of speech, profound psychomotor retardation, epilepsy, and autism, although molecular diagnostics has proven that variant clinical forms exist.3,4 It has recently been shown that missense mutations in MECP2 can cause severe neonatal encephalopathy in boys.5 Classic Rett phenotypes in boys have so far only been reported in rare cases of somatic mosaicism or XXY karyotypes.6–11 In girls, larger intragenic deletions are responsible for about 11–16% of typical Rett syndrome without point mutations in the coding exons.12,13 Larger deletions have not yet been found in boys, and duplications of MECP2 have not yet been reported as a cause for typical Rett syndrome at all. We have established quantitative PCR for diagnosis of deletions affecting MECP2 , and in this paper, we report a boy manifesting clinical features of Rett syndrome and a submicroscopic duplication within the cytogenetic band Xq28 encompassing the entire MECP2 gene. The boy is the second child of healthy, unrelated parents, whose older brother had developed normally. There is no family history of mental retardation or developmental disorders. The patient was born in the 41st week after an uneventful pregnancy. Birth was spontaneous but with protracted labour (birth weight 3940 g, length 54 cm, head …

Spinocerebellar ataxia type 6: genotype and phenotype in German kindreds

OBJECTIVE Spinocerebellar ataxia type 6 (SCA6) is an autosomal dominant cerebellar ataxia (ADCA) of which the mutation causing the disease has recently been characterised as an expanded CAG trinucleotide repeat in the gene coding for the α1A-subunit of the voltage dependent calcium channel. The aim was to further characterise the SCA6 phenotype METHODS The SCA6 mutation was investigated in 69 German families with ADCA and 61 patients with idiopathic sporadic cerebellar ataxia and the CAG repeat length of the expanded allele was correlated with the disease phenotype. RESULTS Expanded alleles were found in nine of 69 families as well as in four patients with sporadic disease. Disease onset ranged from 30 to 71 years of age and was significantly later than in other forms of ADCA. Age at onset correlated inversely with repeat length. The SCA6 phenotype comprises predominantly cerebellar signs in concordance with isolated cerebellar atrophy on MRI. Non-cerebellar systems were only mildly affected with external ophthalmoplegia, spasticity, peripheral neuropathy, and parkinsonism. Neither these clinical signs nor progression rate correlated with CAG repeat length. CONCLUSIONS This study provides the first detailed characterisation of the SCA6 phenotype. Clinical features apart from cerebellar signs were highly variable in patients with SCA6. By comparison with SCA1, SCA2, and SCA3 no clinical or electrophysiological finding was specific for SCA6. Therefore, the molecular defect cannot be predicted from clinical investigations. In Germany, SCA6 accounts for about 13% of families with ADCA. However, up to 30% of SCA6 kindreds may be misdiagnosed clinically as sporadic disease due to late manifestation in apparently healthy parents. Genetic testing is therefore recommended for the SCA6 mutation also in patients with putative sporadic ataxia.

An Isoform of Ataxin-3 Accumulates in the Nucleus of Neuronal Cells in Affected Brain Regions of SCA3 Patients

Autosomal dominant spinocerebellar ataxias (SCA) form a group of clinically and genetically heterogeneous neurodegenerative disorders. The defect responsible for SCA3/Machado‐Joseph disease (MJD) has been identified as an unstable and expanded (CAG)n trinucleotide repeat in the coding region of a novel gene of unknown function. The MJD1 gene product, ataxin‐3, exists in several isoforms. We generated polyclonal antisera against an alternate carboxy terminus of ataxin‐3. This isoform, ataxin‐3c, is expressed as a protein of approximately 42 kDa in normal individuals but is significantly enlarged in affected patients confirming that the CAG repeat is part of the ataxin‐3c isoform and is translated into a polyglutamine stretch, a feature common to all known CAG repeat disorders. Ataxin‐3 like immunoreactivity was observed in all human brain regions and peripheral organs studied. In neuronal cells of control individuals, ataxin‐3c was expressed cytoplasmatically and had a somatodendritic and axonal distribution. In SCA3 patients, however, C‐terminal ataxin‐3c antibodies as well as antiataxin‐3 monoclonal antibodies (1H9) and anti‐ubiquitin antibodies detected intranuclear inclusions (NIs) in neuronal cells of affected brain regions. A monoclonal antibody, 2B6, directed against an internal part of the protein, barely detected these NIs implying proteolytic cleavage of ataxin‐3 prior to its transport into the nucleus. These findings provide evidence that the alternate isoform of ataxin‐3 is involved in the pathogenesis of SCA3/MJD. Intranuclear protein aggregates appear as a common feature of neurodegenerative polyglutamine disorders.

Polymorphisms in the DLG5 and OCTN cation transporter genes in Crohn’s disease

Background and aims: Recent data suggest identification of causal genetic variants for inflammatory bowel disease in the DLG5 gene and in the organic cation transporter (OCTN) cluster, both situated in previously described linkage regions. Patients and methods: The polymorphisms in DLG5 (113 G→A, 4136 C→A, and DLG5_e26), SLC22A4 (1672 C→T), and SLC22A5 (−207 G→C) were assessed in 625 patients with Crohn’s disease (CD), 363 patients with ulcerative colitis (UC), and 1012 healthy controls. Association with disease susceptibility, clinical phenotypes, and possible genetic interactions of these polymorphisms with disease associated CARD15/NOD2 mutations was analysed. Results: No significant association of DLG5 polymorphisms with CD or UC was observed. Homozygosity for the OCTN-TC haplotype was associated with an increased CD risk (OR = 1.65), which was even greater in the presence of CARD15 mutations. Genotype-phenotype analysis revealed that this association was particularly strong in patients with colonic disease. The TC haplotype was associated with non-fistulising non-fibrostenotic disease, an earlier age of disease onset, and reduced need for surgery. Conclusion: Our observations argue against a role of DLG5 polymorphisms in the susceptibility for inflammatory bowel disease, whereas the OCTN polymorphisms are associated with CD. However, due to the comparable weak association observed herein, extended linkage disequilibrium analyses of these variants with the IBD5 haplotype tagged single nucleotide polymorphims might be advisable before definitive conclusions about their causative role in CD can be drawn.

Mutation analysis and association studies of the UCHL1 gene in German Parkinson's disease patients.

Recently, an Ile93Met substitution has been identified in the ubiquitin carboxy-terminal hydrolase L1 (UCHL1) gene in a single German PD family with autosomal dominant inheritance. To determine whether mutations in the UCHL1 gene are causative for Parkinsons disease (PD) a detailed mutation analysis was performed in a large sample of German sporadic and familial PD patients. We found no disease-causing mutation in the coding region of the UCHL1 gene. Direct sequencing revealed six intronic polymorphisms in the UCHL1 gene. Analysis of an S18Y polymorphism in exon 3 of the UCHL1 gene in sporadic PD patients and controls showed carriers of allele 2 (tyrosine) significantly less frequent in patients with a reduced risk of 0.57 (CI = 0.36–0.88; p = 0.012, pc = 0.047, χ2 = 6.31). Our study shows that sequence variations in the coding region of UCHL1 are a rare event. A protective effect of a certain UCHL1 variant in the pathogenesis of sporadic PD is suggested, underlining the relevance of UCHL1 in neurodegeneration.

ALTERNATIVE REPRODUCTIVE TACTICS AND REPRODUCTIVE SUCCESS IN MALE RHESUS MACAQUES

Male rhesus macaques on Cayo Santiago use rank-dependent alternative reproductive tactics. High-ranking males can form long-term consorts and guard female mates while low-ranking males frequently resort to quick copulations under the cover of vegetation. No single reproductive tactic provided the Group S males with a definitive reproductive advantage during the one-year study. Males using the long-term tactic and the quick, stealth tactic sired five offspring each, but fewer males used the long-term consort tactic. Males using the long-term reproductive tactic have significantly greater mating success than males using the quick, sneaky tactic, and may have greater reproductive success. The highest-ranking males who form long-term consorts had the greatest degree of reproductive success. This indicates that for the highest-ranking males, forming long-term consorts is the most effective reproductive tactic. The effectiveness of alternative tactics for high-ranking males (i.e. consort disruption and possessive following) was equivocal. Consort disruption had no immediate effect on reproductive success. Possessive following may have resulted in the siring of two offspring by the alpha male, but was ineffective in other cases, where the females were inseminated by subordinate males. The effectiveness of the quick, furtive tactic was demonstrated by the siring of 45% of the infants by males who used this tactic.