The Prader-Willi syndrome (PWS) is a human imprinting disorder resulting from genomic alterations that inactivate imprinted, paternally expressed genes in human chromosome region 15q11-q13. This genetic condition appears to be a contiguous gene syndrome caused by the loss of at least 2 of a number of genes expressed exclusively from the paternal allele, including SNRPN, MKRN3, MAGEL2, NDN and several snoRNAs, but it is not yet well known which specific genes in this region are associated with this syndrome. Prader-Will-Like syndrome (PWLS) share features of the PWS phenotype and the gene functions disrupted in PWLS are likely to lie in genetic pathways that are important for the development of PWS phenotype. However, the genetic basis of these rare disorders differs and the absence of a correct diagnosis may worsen the prognosis of these individuals due to the endocrine-metabolic malfunctioning associated with the PWS. Therefore, clinicians face a challenge in determining when to request the specific molecular test used to identify patients with classical PWS because the signs and symptoms of PWS are common to other syndromes such as PWLS. This review aims to provide an overview of current knowledge relating to the genetics of PWS and PWLS, with an emphasis on identification of patients that may benefit from further investigation and genetic screening.
Alleles ; Chromosomes, Human ; Diagnosis ; Genetic Testing ; Genetics* ; Humans ; Phenotype ; Prader-Willi Syndrome* ; Prognosis ; RNA, Small Nucleolar ; snRNP Core Proteins

The Prader-Willi syndrome (PWS) is a human imprinting disorder resulting from genomic alterations that inactivate imprinted, paternally expressed genes in human chromosome region 15q11-q13. This genetic condition appears to be a contiguous gene syndrome caused by the loss of at least 2 of a number of genes expressed exclusively from the paternal allele, including SNRPN, MKRN3, MAGEL2, NDN and several snoRNAs, but it is not yet well known which specific genes in this region are associated with this syndrome. Prader-Will-Like syndrome (PWLS) share features of the PWS phenotype and the gene functions disrupted in PWLS are likely to lie in genetic pathways that are important for the development of PWS phenotype. However, the genetic basis of these rare disorders differs and the absence of a correct diagnosis may worsen the prognosis of these individuals due to the endocrine-metabolic malfunctioning associated with the PWS. Therefore, clinicians face a challenge in determining when to request the specific molecular test used to identify patients with classical PWS because the signs and symptoms of PWS are common to other syndromes such as PWLS. This review aims to provide an overview of current knowledge relating to the genetics of PWS and PWLS, with an emphasis on identification of patients that may benefit from further investigation and genetic screening.
Alleles ; Chromosomes, Human ; Diagnosis ; Genetic Testing ; Genetics* ; Humans ; Phenotype ; Prader-Willi Syndrome* ; Prognosis ; RNA, Small Nucleolar ; snRNP Core Proteins

OBJECTIVE: To establish two methods by denaturing gradient gel electrophoresis (DGGE) and pyrosequencing for genotyping rs220030 (a SNP in the promoter region of small nuclear ribonucleoprotein polypeptide N, SNRPN). To establish an analytical technique for detecting CpG methylation status by pyrosequencing and to further investigate the feasibility of applying rs220030 to the determination of parental origin allele. METHODS: The rs220030 of 97 blood samples from individuals of Shanghai Han population were genotyped by DGGE, meanwhile the rs220030 of 25 blood samples of them were genotyped by pyrosequencing to compare the two methods in genotyping SNP. Pyrosequencing united bisulfite conversion method was applied to detect CpG methylation status of region upstream rs220030 of two random blood genealogical samples and investigate whether the methylation status was parental related. RESULTS: The rs220030 genotyping results of 97 blood samples detected by DGGE were 20 C homozygote, 29 T homozygote, and 48 C/T heterozygote. Twenty-five blood samples genotyped by pyrosequencing showed the same result with DGGE. The CpG methylation status of region upstream rs220030 of the child was similar to the mother. CONCLUSION Compared with DGGE, pyrosequencing is more accurate, convenient, and suitable for large samples and high throughput SNP genotyping. Pyrosequencing united bisulfite conversion can be used to detect CpG methylation status precisely. It is feasible to apply rs220030 to parental origin allele determination.
Asian People/genetics* ; CpG Islands ; DNA/genetics* ; DNA Methylation ; DNA Primers ; Genomic Imprinting ; Genotype ; Heterozygote ; Humans ; Polymorphism, Single Nucleotide ; Sequence Analysis, DNA ; Sulfites/metabolism* ; snRNP Core Proteins/genetics*

Objective: To study the expression and effect of small nuclear ribonucleoprotein-associated protein B (SNRPB) on proliferation and metastasis of liver cancer tissues and cells. Methods: The bioinformatics database starBase v3.0 and GEPIA were used to analyze the expression of SNRPB in liver cancer tissue and normal liver tissue, as well as the survival and prognosis of liver cancer patients. The expression of SNRPB mRNA and protein in liver cancer cell lines were analyzed by qRT-PCR and Western blot. RNA interference technique (siRNA) was used to determine SNRPB protein expression down-regulation. The proliferation effect on hepatocellular carcinoma cells was observed by MTT assay. Transwell invasion and migration assay was used to detect the changes in the metastatic ability of liver cancer cells after SNRPB down-regulation. Western blot was used to detect the changes of epithelial mesenchymal transition (EMT) markers in liver cancer cells after down-regulation of SNRPB expression. Data were compared between two groups and multiple groups using t-test and analysis of variance. Results: The expression of SNRPB was significantly higher in liver cancer tissue than normal liver tissue, and its expression level was correlated with the prognosis of liver cancer patients. Compared with the immortalized hepatocyte LO(2), the expression of SNRPB was significantly increased in the liver cancer cells (P < 0.01). siRNA-SNRPB had significantly inhibited the expression of SNRPB mRNA and protein in liver cancer cells. MTT results showed that the absorbance value was lower in SNRPB knockdown group than negative control group, and the difference at 96 h after transfection was most significant (P < 0.01). Transwell assay results showed that compared with the negative control group, the SNRPB knockdown group (MHCC-97H: 121.27 ± 8.12 vs. 46.38 ± 7.54; Huh7: 126.50 ± 6.98 vs. 41.10 ± 8.01) invasion and migration (MHCC-97H: 125.20 ± 4.77 vs. 43.18 ± 7.32; Huh7: 132.22 ± 8.21 vs. 38.00 ± 6.78) ability was significantly reduced (P < 0.01) in liver cancer cells. Western blot showed that the expression level of epithelial phenotype marker E-cadherin was decreased after down-regulation of SNRPB, while the expression levels of mesenchymal phenotype markers N-cadherin and vimentin was increased, suggesting that down-regulation of SNRPB inhibited EMT in liver cancer cells. Conclusion: SNRPB expression is significantly increased in liver cancer tissues and cells, and it is involved in regulating the proliferation, metastasis and EMT of liver cancer cells.
Carcinoma, Hepatocellular/genetics* ; Cell Line, Tumor ; Cell Movement ; Cell Proliferation ; Epithelial-Mesenchymal Transition ; Gene Expression Regulation, Neoplastic ; Humans ; Liver Neoplasms/genetics* ; snRNP Core Proteins

OBJECTIVEPrader-Willi syndrome (PWS) is an example of a human genetic disorder that involves imprinting genes on the proximal long arm of chromosome 15 and SNRPN gene as a candidate gene for this syndrome. The purpose of this study was to show the molecular genetic defects and genomic imprinting basis in Chinese PWS patients and to evaluate the clinical applications of a differential diagnostic test for PWS.

METHODSFluorescence in situ hybridization (FISH) and methylation-specific PCR (MSPCR) techniques were applied for 4 clinically suspected PWS patients. Using three probes, including SNRPN probe for identification of the critical locus in PWS region, D15Z1 and PML control probes for identification of the 15p arm and 15q arm, the authors detected the deletions 15q in PWS. MSPCR was based on sodium bisulfite treatment of DNA and PCR primers specific for the maternal and paternal allele.

RESULTSWhen hybridized with mixed probes, it was found in 2 patients that the central specific signal was absent, but both the flanking control signals were retained, indicating SNRPN gene deletion of chromosome 15q11-13. Bisulfite-modified DNA from all PWS children amplified with methylated allele-specific primer pair showed only maternal 131bp PCR product, indicating the maternal uniparental disomy (UPD15).

CONCLUSIONGenomic imprinting plays an important role in the molecular pathogenesis of PWS that caused by paternal microdeletions of 15q11-q13 or maternal UPD of chromosome 15. The basic defect seemed to be an absence of function of PWS genes that are normally expressed only from the paternal chromosome 15. MSPCR is a rapid and simple PCR-based assay compared with other cyto-molecular tests and its results were consistent with the clinical diagnosis of PWS, so it seems to be a reliable diagnostic method for PWS patients who show abnormal methylation at SNRPN. The genetic differential tests for PWS are important in determining familial recurrence risk.

Adolescent ; Autoantigens ; Chromosome Deletion ; Chromosomes, Human, Pair 15 ; genetics ; Gene Deletion ; Genomic Imprinting ; genetics ; Humans ; In Situ Hybridization, Fluorescence ; Male ; Polymerase Chain Reaction ; methods ; Prader-Willi Syndrome ; genetics ; Ribonucleoproteins, Small Nuclear ; genetics ; snRNP Core Proteins

OBJECTIVE: To analyze the polymorphism of rs220030, a SNP which is located in the promoter region of small nuclear ribonucleoprotein polypeptide N (SNRPN) gene in the Chinese Han population and to obtain the data of population genetics. METHODS: The denaturing gradient gel electrophoresis (DGGE) method was applied to detect the polymorphism of rs220030 in 100 unrelated and healthy individuals from the Shanghai Han population. The genotyping result of this SNP was confirmed by TaqMan assay in some typical samples. RESULTS: DGGE results showed 4 bands for CT heterozygote, and 1 band for CC or TT homozygote, and those results were confirmed by The TaqMan SNP genotyping assays. Genotyping results showed 34 individuals with CC, 41 with CT and 25 with TT of rs220030. The allele frequencies for C and T were 0.545 and 0.455, respectively. H was 0.500, PIC was 0.373, DP was 0.654, and PE was 0.186. The distribution of genotype frequencies were in Hardy-Weinberg equilibrium. CONCLUSION DGGE is a quick and effective method in the analysis of SNP polymorphism in small population. Statistical parameters of rs220030 for forensic evaluation meet the requirements for forensic identification and paternity testing.
Alleles ; Asian People/genetics* ; China/ethnology* ; DNA Primers ; Denaturing Gradient Gel Electrophoresis/methods* ; Gene Frequency ; Genetic Markers ; Genetics, Population ; Genotype ; Heterozygote ; Humans ; Polymerase Chain Reaction ; Polymorphism, Single Nucleotide/genetics* ; Promoter Regions, Genetic ; snRNP Core Proteins/genetics*

OBJECTIVETo perform mutation analysis and describe the genotype of the SMN gene in a patient with spinal muscular atrophy (SMA) and his family.

METHODSDeletion analysis of the SMN1 exon 7 by conventional PCR-restriction fragment length polymorphism (RFLP) and allele-specific PCR, and gene dosage of SMN1 and SMN2 by multiplex ligation-dependent probe amplification (MLPA) were performed for the patient and his parents; reverse transcriptase (RT)-PCR and sequencing were performed for the patient. To determine whether the SMN variant was exclusive to transcripts derived from SMN1, the RT-PCR product of the patient was subcloned and multiple clones were sequenced directly; PCR of SMN exon 5 from the genomic DNA of the parents and direct sequencing were performed to confirm the mutation.

RESULTSIn SMN1 exon 7 deletion analysis, no homozygous deletion of the SMN1 was observed in the family; the gene dosage analysis by MLPA showed that the patient had 1 copy of SMN1 and 1 copy of SMN2 his father had 2 copies of SMN1 and 2 copies of SMN2, and his mother had 1 copy of SMN1 and no SMN2. A previously unreported missense mutation of S230L was identified from the patient and this mutation was also found in his father.

CONCLUSIONA novel missense mutation of S230L was identified in the SMA family and the genotype of the family members were investigated.

Base Sequence ; Child, Preschool ; DNA Mutational Analysis ; Exons ; genetics ; Humans ; Male ; Molecular Sequence Data ; Muscular Atrophy, Spinal ; genetics ; Reverse Transcriptase Polymerase Chain Reaction ; SMN Complex Proteins ; genetics ; Spinal Muscular Atrophies of Childhood ; genetics ; Survival of Motor Neuron 1 Protein ; genetics ; snRNP Core Proteins ; genetics