Document Detail


An essential SMN interacting protein (SIP1) is not involved in the phenotypic variability of spinal muscular atrophy (SMA).
MedLine Citation:
PMID:  10909848     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The survival motor neuron (SMN) protein and the SMN interacting protein 1 (SIP1) are part of a 300 kD protein complex with a crucial role in snRNP biogenesis and pre-mRNA splicing. Both proteins are colocalised in nuclear structures called gems and in the cytoplasm. Approximately 96% of patients with autosomal recessive spinal muscular atrophy (SMA) show mutations in the SMN1 gene, while about 4% fail to show any mutation, despite a typical SMA phenotype. Additionally, sibs with identical 5q13 homologs and homozygous absence of SMN1 can show variable phenotypes which suggest that SMA is modified by other, yet unknown factors. Since both genes, SMN1 and SIP1, belong to the same pathway and are part of the same protein complex, it is obvious to ask whether mutations within SIP1 are responsible for both the phenotypic variability and the appearance of non-SMN mutated SMA patients. First, we identified the chromosomal location of SIP1 and assigned it to chromosomal region 14q13-q21 by fluorescence in situ hybridisation. No SMA related disorder has yet been assigned to this chromosomal region. Next, we determined the exon-intron structure of the SIP1 gene which encompasses 10 exons and identified five transcription isoforms. We sequenced either RT-PCR products or genomic DNA covering the complete coding region from 23 typical SMA patients who had failed to show any SMN1 mutation. No mutation and no polymorphism was found within SIP1. Additionally, we sequenced RT-PCR products or genomic fragments of the entire SIP1 coding region from 26 sibs of 11 SMA families with identical genotypes (delta7SMN/delta7SMN or delta7SMN/other mutation) but different phenotypes and again no mutation was found. Finally, we performed quantitative analysis of RT-PCR products from the same 26 sibs. No difference in expression level of the five isoforms among phenotypically variable sibs was observed. Based on these data, we suggest that neither the phenotypic variability nor the 5q-unlinked SMA are caused by mutations within SIP1.
Authors:
C Helmken; A Wetter; S Rudnik-Schöneborn; T Liehr; K Zerres; B Wirth
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  European journal of human genetics : EJHG     Volume:  8     ISSN:  1018-4813     ISO Abbreviation:  Eur. J. Hum. Genet.     Publication Date:  2000 Jul 
Date Detail:
Created Date:  2000-10-04     Completed Date:  2000-10-26     Revised Date:  2011-09-28    
Medline Journal Info:
Nlm Unique ID:  9302235     Medline TA:  Eur J Hum Genet     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  493-9     Citation Subset:  IM    
Affiliation:
Institute of Human Genetics, Bonn, Germany.
Data Bank Information
Bank Name/Acc. No.:
GENBANK/AJ250932;  AJ250933;  AJ250934;  AJ250935;  AJ250936;  AJ250937;  AJ250938;  AJ250939
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MeSH Terms
Descriptor/Qualifier:
Alternative Splicing
Child, Preschool
Chromosomes, Human, Pair 14 / genetics
DNA / analysis,  blood
DNA Mutational Analysis
DNA Primers / chemistry
Exons
Genetic Testing
Genotype
Humans
In Situ Hybridization, Fluorescence
Infant
Introns
Molecular Sequence Data
Motor Neurons / metabolism,  pathology
Mutation
Nerve Tissue Proteins / genetics*
Phenotype*
RNA, Messenger / analysis
RNA-Binding Proteins
Reverse Transcriptase Polymerase Chain Reaction
Spinal Muscular Atrophies of Childhood / genetics*,  pathology
Chemical
Reg. No./Substance:
0/DNA Primers; 0/GEMIN2 protein, human; 0/Nerve Tissue Proteins; 0/RNA, Messenger; 0/RNA-Binding Proteins; 9007-49-2/DNA

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