[Clinical details and genetics of recessive ataxias]. / Klinik und Genetik der rezessiven Ataxien.

Autosomal recessive cerebellar ataxias (ARCA) are a heterogeneous group of rare neurological diseases affecting both the central and the peripheral nervous systems. They are characterized by autosomal recessive inheritance, progressive ataxia and degeneration of the cerebellum and spinal cord. Onset is generally before the third decade of life. The most frequent of these rare disorders in the Caucasian population is Friedreich's ataxia followed by ataxias with oculomotor apraxia. ARCAs are caused by mutations at specific loci but not every affected gene is known to date. Clinical diagnosis can be confirmed by ancillary tests (biochemical, neuroimaging and electrophysiological investigations) and mutation analyses if the causative gene has been identified. Correct clinical and genetic diagnosis is necessary for prognosis, genetic counseling and pharmacological treatment. For the majority of ARCAs a curative treatment is not available.

Ataxia with oculomotor apraxia type 2: novel mutations in six patients with juvenile age of onset and elevated serum alpha-fetoprotein.

Ataxia with oculomotor apraxia type 2 (AOA2), a neurodegenerative disorder with juvenile to adolescent onset is caused by mutations within the SENATAXIN gene ( SETX). We performed molecular analyses in six patients showing clinically an AOA2 phenotype and moderate to significant elevated serum alpha-fetoprotein levels. Sequencing the 24 coding exons and flanking intronic sequences revealed 11 novel DNA variations, including seven unknown missense mutations, a dinucleotide deletion, a four-nucleotide deletion affecting the 5' splice site of exon 22 and two sequence variations, which are considered to be polymorphisms. By molecular testing the clinical diagnosis has been confirmed in all patients.

High frequency of partial SPAST deletions in autosomal dominant hereditary spastic paraplegia.

BACKGROUND: Hereditary spastic paraplegia (HSP) is a genetically heterogeneous neurodegenerative disease. The most frequent cause of autosomal dominant HSP is mutation of SPAST (SPG4 locus), but additional pedigrees remain mutation negative by conventional screening despite linkage to SPG4. OBJECTIVE: To determine the frequency of genomic copy number aberrations of SPAST in autosomal dominant HSP. METHODS: We developed and validated a multiplex ligation-dependent probe amplification assay targeting SPAST and SPG3A, another gene frequently involved in autosomal dominant HSP. In a multicenter study we subsequently investigated 65 index patients with autosomal dominant HSP, all of whom had previously been screened negative for SPAST mutations. Independent secondary samples, additional family members, and cDNA were analyzed to confirm positive findings. RESULTS: Aberrant MLPA profiles were identified in 12 cases (18%). They exclusively affect SPAST, represent deletions, segregate with the disease, and are largely pedigree specific. Internal SPAST deletions entail expression of correspondingly shortened transcripts, which vary in stability. Age at onset in SPAST deletion carriers does not differ from that associated with other SPAST mutations. CONCLUSIONS: Partial SPAST deletions, but not SPAST amplifications and SPG3A copy number aberrations, represent an underestimated cause of autosomal dominant hereditary spastic paraplegia. Partial SPAST deletions are likely to act via haploinsufficiency.

[Best's disease with normal EOG. Case report of familial macular dystrophy]. / Morbus Best mit normalem EOG. Fallvorstellung einer familiären Makuladystrophie.

Best's disease is an autosomal dominant disorder with incomplete penetrance and variable expression. A typical characteristic of Best's disease is a pathological EOG. We describe four members of a family with bilateral, subfoveal vitelliform lesions. The EOG was normal in all cases. Genetic analysis of the oldest son indicated a heterozygotic mutation Ala234Val in the VMD2 gene, so-called bestrophin gene, which is associated with Best's disease. Molecular genetic analysis also found Best's disease with a normal EOG. A normal EOG cannot exclude Best's disease. The family members should receive genetic consultation and if wished analysis of the VMD2 gene.

Early age of onset in fatal familial insomnia. Two novel cases and review of the literature.

Fatal familial insomnia (FFI) is a prion disease exhibiting the PRNP D178N/129M genotype. Features of this autosomal dominant illness are progressive insomnia, dysautonomia, myoclonus, cognitive decline and motor signs associated with thalamic nerve cell loss and gliosis. In contrast to the new variant of Creutzfeldt-Jakob disease (vCJD) the onset of FFI is in middle to late adulthood. We report two male patients who belong to a large German FFI kindred. They were examined clinically, and postmortem neuropathological examination was carried out in collaboration with the German reference centre for prion disease. Additionally, the prion protein gene (PRNP) was analysed. To identify further patients with disease onset under 30 years of age a comprehensive literature review was carried out. Two male patients presented with typical symptoms of FFI at the age of 23 and 24 years. In their kindred, the age of onset has never before been under 44 years of age. Our literature review identified five additional early onset cases who died at age 21 to 25 years. In all 22 reviewed FFI families the median manifestation age was 49.5 years. Although phenotypic variability of FFI is common, age of onset under 30 years has been considered to be a hallmark of vCJD with a mean manifestation at 27 years of age. Our findings underline that in addition to vCJD, FFI must be considered in cases of young-onset prion disease. This has considerable impact on clinical management and genetic counselling.

Neonatal seizures in two sisters with incontinentia pigmenti.

Familial incontinentia pigmenti (IP) (OMIM #308300) is a rare genetic disorder which segregates in an X-linked dominant way. The female-to-male ratio ranges from 20 to 37 : 1. In affected females IP causes highly variable abnormalities of the skin, hair, nails, teeth, eyes, and central nervous system (CNS). Cardiovascular anomalies, cerebral infarction, and immune dysfunction are rare complications of IP. The pathogenesis of cerebral changes in IP remains elusive. We report the case of two IP-affected sisters who presented in each case with neonatal seizures on the fifth day of life. Via cranial magnetic resonance tomographic imaging (MRI) different types of lesions in both hemispheres were demonstrable in both patients. To date the pathogenetic mechanisms for the cerebral lesions are not fully understood. However, multiple microscopic infarcts could serve as a possible explanation. The clinical course and the neurological development of the older child are favorable and so far the younger sibling appears to be developing normally, which is uncommon for patients with early onset of neurological symptoms. Symptomatic seizures in IP are an important differential diagnosis in benign non-familial and familial neonatal seizures.

One novel and two recurrent missense DKC1 mutations in patients with dyskeratosis congenita (DKC).

X-linked dyskeratosis congenita (DKC) is a progressive multisystem disorder most severely affecting tissues with a high cellular turnover such as skin, mucous membranes, and blood. Most patients die of bone marrow failure, although the chances of succumbing to various types of cancer and pulmonary disease are also high. DKC is caused predominantly by missense mutations in the DKC1 gene linked to Xq28. Some of the clinical features are reminiscent of premature ageing and this agrees with recent indications that DKC could be a telomere maintenance disorder. There is considerable variability in the type, severity, and age at onset of the various anomalies. Recognition of this has increased with the finding that patients with Hoyeraal-Hreidarsson syndrome (HHS) who exhibit severe neurological problems in addition to early-onset pancytopenia, also bear mutations in the DKC1 gene. For these reasons, and compounded by the range of mutations, phenotype-genotype correlations and accurate assessments of prognosis have not been possible. To complement the present data, we here report on three new cases of DKC and their mutations. One is a novel mutation in the exon 3 (K43E). The other two represent a frequently recurring mutation in exon 11 (A353V) and a less frequently recurring mutation in the exon 3 (T49M).

The GAA repeat expansion in intron 1 of the frataxin gene is related to the severity of cardiac manifestation in patients with Friedreich's ataxia.

Friedreich's ataxia is an autosomal recessive disorder characterized by spinocerebellar degeneration. It is caused by an unstable GAA trinucleotide repeat expansion (>120 repeats) in the first intron of the frataxin gene on chromosome 9 (9q13) in both alleles. Concentric left ventricular hypertrophy has been recognized as the major cardiac manifestation of Friedreich's ataxia. Our aim was to investigate the influence of the frataxin repeat length on cardiac hypertrophy in patients with Friedreich's ataxia and in patients with hypertrophic and dilated cardiomyopathy. Thirty-one patients with Friedreich's ataxia, 86 patients with hypertrophic cardiomyopathy, 134 patients with dilated cardiomyopathy, and 32 healthy individuals without cardiac disease were analysed by electrocardiography and 2D-M-mode echocardiography. Then, the size of the frataxin repeat was determined by polymerase chain reaction (PCR) and agarose gel electrophoresis. The number of GAA repeats in patients with hypertrophic and dilated cardiomyopathy was not different from the length in patients without cardiac disease (hypertrophic cardiomyopathy, 8+/-2 repeats on GAA 1 allele and 11+/-5 repeats on GAA 2 allele; dilated cardiomyopathy, 7+/-2 repeats on GAA 1 allele and 11+/-5 repeats on GAA 2 allele; Control, 9+/-1 repeats on GAA 1 allele and 12+/-6 repeats on GAA 2 allele). The septal and posterior wall thickness of these patients was not related to the GAA repeat length. All patients with Friedreich's ataxia had two enlarged alleles with a mean GAA repeat length of 757+/-316 and 1012+/-231, respectively. The lengths of both alleles were significantly greater than the lengths in the controls (P<0.0001), patients with hypertrophic cardiomyopathy (P<0.0001) and dilated cardiomyopathy (P<0.0001). A significant correlation was revealed between interventricular septal hypertrophy and frataxin repeat length in the smaller allele. Furthermore, the ratio of septal to posterior wall thickness was significantly correlated to GAA repeat size on the smaller allele. In conclusion, the size of the GAA repeat on the smaller allele in the frataxin gene is associated with the degree of left ventricular hypertrophy in patients with Friedreich's ataxia but is not related to the severity of hypertrophic cardiomyopathy.

Novel twelve-generation kindred of fatal familial insomnia from germany representing the entire spectrum of disease expression.

We present a novel large German kindred of fatal familial insomnia (FFI) consisting of three branches and comprising more than 800 individuals of 12 generations, the largest pedigree of any familial prion disease known today. There is a wide spectrum of clinical presentations leading to misdiagnoses of Olivo-Ponto-Cerebellar Atrophy (OPCA), Parkinson's or Alzheimer's disease in addition to Creutzfeldt-Jakob disease (CJD) and Gerstmann-Sträussler-Scheinker (GSS) syndrome. Molecular genetic analysis of the prion protein gene (PRNP) confirmed the mutation D178N segregating with methionine at the polymorphic codon 129 of PRNP in all 7 patients examined. This polymorphism at codon 129 is supposed to discriminate between familial CJD (fCJD) and FFI; the 129M allele determines FFI and 129V fCJD. Furthermore, heterozygosity at this site appears to induce prolonged disease duration as compared to the homozygous condition. The variability of the clinical and pathological findings documented for our patients indicates the difficulty in establishing the diagnosis of FFI on clinical and on pathological grounds alone. In three cases (IX-97, XI-21, V-2) followed up by us prospectively insomnia was an early and severe symptom; however, in case notes analyzed retrospectively this symptom was frequently missed. In contrast to previous reports and in agreement with recent studies we cannot confirm a clear relationship between the status of the M/V polymorphism at codon 129 and the age-of-onset of this disease.

Another case of achalasia-microcephaly syndrome.

The first German patient with achalasia-microcephaly syndrome is described. The mother was exposed to the anti-malarial drug Mefloquine during the first 8 weeks of pregnancy.

Linkage disequilibrium and haplotype analysis in German Friedreich ataxia families.

The main mutation causing Friedreich ataxia (FRDA) is the expansion of a GAA repeat localized within the intron between exon 1 and exon 2 of the gene X25. This expansion has been observed in 98% of FRDA chromosomes. To analyze frequencies of markers tightly linked to the Friedreich ataxia gene and to investigate wheter a limited number of ancestral chromosomes are shared by German FRDA families, a detailed analysis employing nine polymorphic markers was performed. We found strong linkage disequilibria and association of FRDA expansions with a few haplotypes. FRDA haplotypes differ significantly from control haplotypes. Our results confirm that GAA repeat expansions in intron 1 of the frataxin gene are limited to a few chromosomes and indicate an obvious founder effect in German patients. Based on these analyses, we estimate a minimum age of the mutation of 107 generations.

SCA6 is caused by moderate CAG expansion in the alpha1A-voltage-dependent calcium channel gene.

Recently, moderate (CAG)>20 repeat expansions in the alpha1A-voltage-dependent calcium channel gene (CACNL1A4) have been identified in a previously unmapped type of SCA which has been named SCA6. We investigated the (CAG)n repeat length of the CACNL1A4 gene in 733 patients with sporadic ataxia and in 46 German families with dominantly inherited SCA which do not harbor the SCA1, SCA2, or MJD1/SCA3 mutation, respectively. The SCA6 (CAG)n expansion was identified in 32 patients most frequently with late manifestation of the disease. The (CAG)n stretch of the affected allele varied between 22 and 28 trinucleotide units and is therefore the shortest trinucleotide repeat expansion causing spinocerebellar ataxia. The (CAG)n repeat length is inversely correlated with the age at onset. In 11 parental transmissions of the expanded allele no repeat instability has been observed. Repeat instability was also not found for the normal allele investigating 431 meioses in the CEPH families. Analyzing 248 apparently healthy octogenerians revealed one allele of 18 repeats which is the longest normal CAG repeat in the CACNL1A4 gene reported. The SCA6 mutation causes the disease in approximately 10% of autosomal dominant SCA in Germany. Most importantly, the trinucleotide expansion was observed in four ataxia patients without obvious family history of the disease which necessitates a search for the SCA6 (CAG)n expansion even in sporadic patients.

SCA2 trinucleotide expansion in German SCA patients.

Autosomal dominant spinocerebellar ataxias (SCA) are a group of clinically and genetically heterogeneous neurodegenerative disorders which lead to progressive cerebellar ataxia. A gene responsible for SCA type 2 has been mapped to human chromosome 12 and the disease causing mutation has been identified as an unstable and expanded (CAG)n trinucleotide repeat. We investigated the (CAG)n repeat length of the SCA2 gene in 842 patients with sporadic ataxia and in 96 German families with dominantly inherited SCA which do not harbor the SCA1 or MJD1/SCA3 mutation, respectively. The SCA2 (CAG)n expansion was identified in 71 patients from 54 families. The (CAG)n stretch of the affected allele varied between 36 and 64 trinucleotide units. Significant repeat expansions occurred most commonly during paternal transmission. Analysis of the (CAG)n repeat lengths with the age of onset in 41 patients revealed an inverse correlation. Two hundred and forty-one apparently healthy octogenerians carried alleles between 16 and 31 repeats. One 50-year old, healthy individual had 34 repeats; she had transmitted an expanded allele to her child. The small difference between 'normal' and disease alleles makes it necessary to define the extreme values of their ranges. With one exception, the trinucleotide expansion was not observed in 842 ataxia patients without a family history of the disease. The SCA2 mutation causes the disease in nearly 14% of autosomal dominant SCA in Germany.

[Noninvasive ventilation of a 4-year-old boy with severe central late onset hypoventilation syndrome]. / Nichtinvasive Beatmung bei einem vierjährigen Jungen mit schwerem zentralen "late onset"-Hypoventilationssyndrom.

BACKGROUND: In the literature we found only five reports about noninvasive ventilation in cases with central hypoventilation syndrome. PATIENT AND METHOD: We report about a 4-year-old boy with severe late onset hypoventilation syndrome. During an interval of 3 months with nasal mask ventilation during sleep he showed an excellent cognitive and statomotoric development. After this time, he needed a noninvasive ventilation with a negative pressure system. RESULTS AND DISCUSSION: In our opinion, noninvasive nasal mask ventilation is a modern method in the treatment of patients with central hypoventilation syndrome. Tracheotomy is only necessary during the first year of life.

Attitudes of German persons at risk for Huntington's disease toward predictive and prenatal testing.

Huntington's disease is an autosomal dominant neurodegenerative disorder characterized by involuntary movements, psychological deterioration and dementia. Indirect predictive testing by linkage analysis has been possible since 1983; direct predictive testing by detecting the instable CAG-repeat has been possible since 1993. Persons at risk were asked, by questionnaire, about their motivation and regarding attitude taking part in indirect and direct predictive and prenatal diagnostics. About half of the interrogated German persons at risk wish to undertake DNA analysis, whereas 32.7% do not want to take part in a direct predictive test. Motives for taking the test are the same as those mentioned in the literature (certainty of carrier status, decisions concerning marriage and further children, planning a career). Motives for not taking the test mostly involve psychological problems in coping with the test result. 45.7% wish to undergo a direct prenatal test (main cause: certainty of the gene status of the child), whereas 27% would not take this test (because of non-toleration of abortion). Only statistical trends could be seen between the intention to take the predictive or prenatal test and some social and demographic variables. The at-risk persons would not change their attitudes regarding indirect or direct predictive and prenatal DNA analysis; they seem to have a confirmed opinion about molecular genetics, mostly depending on familial and social background.

Autosomal dominant familial spastic paraplegia: reduction of the FSP1 candidate region on chromosome 14q to 7 cM and locus heterogeneity.

Three large pedigrees of German descent with autosomal dominant "pure" familial spastic paraplegia (FSP) were characterized clinically and genetically. Haplotype and linkage analyses, with microsatellites covering the FSP region on chromosome 14q (locus FSP1), were performed. In pedigree W, we found a haplotype that cosegregates with the disease and observed three crossing-over events, reducing the FSP1 candidate region to 7 cM; in addition, the observation of apparent anticipation in this family suggests a trinucleotide repeat expansion as the mutation. In pedigrees D and S, the gene locus could be excluded from the whole FSP1 region, confirming the locus heterogeneity of autosomal dominant FSP.

Del(2q)--cause of the wrinkly skin syndrome?

We report the cases of a mother and her two sons with del(2) (q32). Their phenotypes are compared with those of 20 individuals reported previously in the literature. All described cases apparently have identical deletions. Common manifestations include small size at birth, retarded growth and development, cranio-facial dysmorphism and skeletal and ocular anomalies. Our patients also have symptoms of the wrinkly skin syndrome (WSS), which is characterized by the wrinkling of the abdominal skin and of the skin of the dorsum of the hands and feet, decreased elastic recoil of the skin, an increased number of palmar and plantar creases, musculoskeletal anomalies, microcephaly, mental retardation and an old appearance. Our three patients show a striking pattern in skin biopsies when viewed by light microscopy, and a peculiar grimacing was noted in the boys. Their serum copper and caeruloplasmin levels are slightly raised.