Familial distal monosomy 3p26.3-pter with trisomy 4q32.2-qter, presenting with progressive ataxia, intellectual disability, and dysmorphic features.

We present a boy diagnosed with partial 3p monosomy and partial 4q trisomy. The patient was 9 years of age with intellectual disability, dysmorphic features, and ataxia. A family history and medical evaluation showed that the father manifested similar facial dysmorphic features, intellectual disability, quadriparesis, and progressive cerebrospinal ataxia. The chromosomal aberration found in the proband was inherited from his father who was found to have a balanced reciprocal translocation of chromosomes 3p and 4q, which was in turn inherited from the paternal grandfather. The final cytogenetic diagnosis according to microarray was 46,XY,der(3)t(3;4)(p26.1;q32.2)arr 3p26.1(39,066-5,363,502)x1,4q32.2q35.2(162,555,236-191,173,881)x3. We describe the cytogenetic investigations that led to the identification of the breakpoints. In addition, we present an overview of the clinical features found in patients with partial 3p monosomies and partial 4q trisomies as reported in the literature.

[Familial occurrence of FXTAS caused by premutation in the FMR1 gene]. / Rodzinne wystepowanie zespolu FXTAS powodowanego premutacja w genie FMRI.

The FMR1 gene premutation has recently been reported to be associated with a neurodegenerative syndrome, characterized by intention tremor, gait ataxia and cognition deficits in persons older than 50 years. We present a 74-year-old man with very severe intention tremor, slight postural tremor and gait ataxia. The molecular analysis revealed that he was a carrier of 91 CGG repeats in the FMR1 gene. His sister (68 years old), with head tremor, was found to be a carrier of 81 CGG repeats, while his younger brother, also with slight head and postural tremor, was a carrier of 98 CGG repeats. Molecular analysis of the proband's asymptomatic daughter revealed an expansion over 120 CGG. Her daughter, with mild intellectual disability, was a carrier of a full mutation. Thus, in the presented family with heterogeneous clinical presentation we found 4 premutations and one full mutation in the FMR1 gene.

[Myotonic dystrophy - a new insight into a well-known disease]. / Dystrofia miotoniczna - nowe spojrzenie na znana chorobe.

Myotonic dystrophy (DM), the most common dystrophy in adults, is an autosomal dominant disease characterized by a variety of multisystemic features. Two genetically distinct forms of DM are identified - type 1 (DM1), the classic form first described by Steinert, and type 2 (DM2), identified by Ricker. DM1 is caused by trinucleotide expansion of CTG in the myotonic dystrophy protein kinase gene, whereas in DM2 the expansion of tetranucleotide repeats (CCTG) in the zinc finger protein 9 gene was identified. Both mutations are dynamic and are located in non-coding parts of the genes. Phenotype variability of DM1 and DM2 is caused by a molecular mechanism due to mutated RNA toxicity. This paper reviews the clinical features of both types of myotonic dystrophies and summarizes current views on pathogenesis of myotonic dystrophy.

The occurrence of spinocerebellar ataxias caused by dynamic mutations in Polish patients.

BACKGROUND AND PURPOSE: Autosomal dominant spinocerebellar ataxias (SCAs) belong to a group of neurodegenerative disorders usually of adult age at onset. Predominant clinical features are progressive ataxia, dysarthria, as well as pyramidal signs and polyneuropathy. Molecular analysis allows particular types of SCA to be distinguished. Genetic tests are applied in 10 types of SCA resulting from dynamic mutations: SCA1, SCA2, SCA3, SCA6, SCA7, SCA8, SCA10, SCA12, SCA17 and DRPLA. MATERIAL AND METHODS: DNA samples from 1598 patients with ataxia symptoms were analysed to establish the number of CAG/CTG repeats in respective genes excluding SCA10. RESULTS: We diagnosed 224 cases of SCA1 (120 families) and 49 cases of SCA2 (23 families). Moreover, presymptomatic testing was done in 85 individuals from SCA1 families and for 21 cases from SCA2 families. An increased number of CTG repeats in the SCA8 gene was observed in 14 families and in 3 families a rare type of SCA, SCA17, was detected. CONCLUSIONS: Our data suggest that frequencies of some types of SCA in Poland are different from those in other European countries, with irregular distribution within the country. The most frequent types are SCA1 and SCA2. A striking feature of the Polish population is the lack of SCA3 - the most frequent type in Western Europe.

Screening for premutation in the FMR1 gene in male patients suspected of spinocerebellar ataxia.

BACKGROUND AND PURPOSE: The aim of this study was to determine the molecular basis of the disorder in patients suspected of spinocerebellar ataxias (SCAs) and search for premutation in the FMR1 gene causing FXTAS among patients in whom 9 SCA types were previously excluded. MATERIAL AND METHODS: DNA obtained from 1385 patients suspected of SCA and 516 controls were used for molecular tests. DNA analysis was carried out by PCR reaction with specific primers. PCR products were separated in denaturing polyacrylamide gels in an ABIPrism 377 sequencer. Amplification of polymorphic regions embracing trinucleotide repeats was performed in the following genes: ATXN1 (SCA1), ATXN2 (SCA2), ATXN3 (SCA3), CACNA1A (SCA6), ATXN7 (SCA7), ATXN80S (SCA8), PPP2R2B (SCA12), TBP (SCA17), ATN1 (DRPLA). Afterwards, a search for FXTAS caused by premutation in the FMR1 gene was performed. Two hundred and sixty-nine subjects selected from the study group with 9 excluded types of SCAs were tested; a subgroup of 178 males aged 50 years was sorted out. RESULTS: Molecular analysis in 1385 individuals revealed SCA1 in 225, SCA2 in 56, SCA8 in 33, SCA17 in 4 subjects. SCA3, SCA6, SCA7, SCA12, and DRPLA were not detected. Within the subgroup aged>or=50 years with ataxia in whom 9 types of SCAs were excluded only one case of FXTAS was detected, which is 1/178 (0.56%), and within the group of males>or=70 years (n=19) one case was also found (5.26%). CONCLUSIONS: The low frequency of FXTAS in the studied material probably results from the fact that the syndrome is much more common in elderly persons (penetrance of the pathogenic premutation gene is higher among elderly individuals).

Searching for mutation in the JPH3, ATN1 and TBP genes in Polish patients suspected of Huntington's disease and without mutation in the IT15 gene.

BACKGROUND AND PURPOSE: The aim of this study was to perform DNA analysis in patients with clinical diagnosis of Huntington's disease (HD) after molecular exclusion of HD and further molecular examinations for other neurodegenerative diseases such as Huntington's disease-like 2 (HDL-2; gene JPH3), dentatorubral pallidoluysian atrophy (DRPLA; gene ATN1) and spinocerebellar ataxia type 17 (SCA17; gene TBP). MATERIAL AND METHODS: The material comprised 224 DNA samples isolated from peripheral blood from patients suspected of HD and 100 DNA samples from unaffected controls. The control group was used to determine the normal range of the number of CAG/CTG repeats in genes JPH3, ATN1 and TBP in the Polish population. Molecular analysis was carried out by PCR reaction, embracing microsatellite repeats in genes JPH3, ATN1 and TBP with specific, fluorescently labelled primers. PCR products were separated in polyacrylamide gels. The normal ranges of the number of repeats established for the control group in genes JPH3, ATN1 and TBP were 7-19, 9-27 and 29-45, respectively. RESULTS: Molecular analysis of DNA from 224 individuals suspected of HD (117 women and 107 men) revealed one case of dynamic mutation - 55 CAG repeats - in the TBP locus (SCA17). No cases of DRPLA or HDL-2 were detected. The range of CAG/CTG repeats for the JPH3 gene in the patient group was 11-19, with the most common alleles containing 14 and 16 repeats. For the ATN1 gene in patients the range of 8-27 repeats was established and the most frequent allele with 16 triplets was present. CONCLUSIONS: The study on 244 patients referred with the clinical diagnosis of HD and without mutation of the IT15 gene revealed one case of SCA17 but did not disclose the presence of two other diseases with a similar clinical manifestation: DRPLA and HDL2.

New analysis method of myotonic dystrophy 1 based on quantitative fluorescent polymerase chain reaction.

Molecular genetic testing of myotonic dystrophy type 1 (DM1) is based on the identification and determination of a cytosine-thymine-guanine (CTG) repeat expansion in the DMPK gene. This is usually done by Southern blot analysis-a time-consuming and very laborious technique requiring high molecular weight DNA. The aim of our study was to develop a highly sensitive, rapid, and cost-effective molecular analysis characterizing the CTG repeat region of the DMPK gene based on a two-step polymerase chain reaction (PCR) protocol. (1) For the detection of alleles of up to 100 repeats, a quantitative fluorescent (QF) amplification with primers flanking the repeat region of the DM1 locus and two reference genes (PAX2 and DHCR7) for standardization was used. By this method it was possible to identify both homozygous and heterozygous DM1 alleles. (2) Long PCR was only performed if a single wild-type allele was detected that gave a QF-PCR signal of only half intensity compared to a homozygous sample. The results obtained using combined QF and Long PCR are highly accurate compared with Southern blot analysis. We conclude that our new rapid analysis is reliable for genetic testing of DM1 patients.