Adolescent ; Exostoses, Multiple Hereditary ; genetics ; Humans ; Male ; Pedigree

OBJECTIVETo study the gene mutation in a patient with multiple exostoses, identify the disease-causing gene mutation.

METHODSPolymerase chain reaction and DNA sequencing were used to screen the EXT1 or EXT2 gene mutation, while mismatch primer amplification and restriction endonuclease digestion were performed to confirm the mutation.

RESULTSBy DNA sequencing, a mutation in the seventh intron was detected and located at 26 bp of 3' splice site upstream in EXT1 gene, which was unreported before. Mismatch primer amplification and restriction fragment length polymorphism analysis suggested that this mutation was not detected in the normal control.

CONCLUSIONThe mutation 1633-26(C-->A) may be the disease-causing mutation in this patient with multiple exostoses.

DNA Mutational Analysis ; Exostoses, Multiple Hereditary ; genetics ; Female ; Humans ; Mutation ; N-Acetylglucosaminyltransferases ; genetics ; Young Adult

Child ; Exostoses, Multiple Hereditary ; genetics ; Female ; Humans ; Mutation ; N-Acetylglucosaminyltransferases ; genetics ; Pedigree

OBJECTIVE: To explore the genetic basis for a pedigree affected with hereditary multiple osteochondroma (HMO). METHODS: Peripheral blood samples were collected from the proband and members of his pedigree with informed consent. Following extraction of genomic DNA, all coding exons and flanking intronic sequences (-10 bp) of the EXT1 and EXT2 genes were subjected to targeted capture and next generation sequencing (NGS). Suspected variant was verified by Sanger sequencing. RESULTS: A heterozygous nonsense variant (c.1911C>A) was found in exon 10 of the EXT1 gene in the proband and his affected father but not in a healthy sister and normal controls. The variant was classified as a pathogenic based on the guidelines of the American College of Medical Genetics and Genomics (PVS1+PM2+PP1). Bioinformatic analysis predicted that the c.1911C>A variant may be disease-causing via nonsense-mediated mRNA decay and anomalous splicing. CONCLUSION The c.1911C>A variant probably underlay the disease in this pedigree. Discovery of this variant enriched the variant spectrum of HMO.
Codon, Nonsense ; Exons/genetics* ; Exostoses, Multiple Hereditary/genetics* ; Heterozygote ; Humans ; Pedigree

OBJECTIVE: To detect EXT1 and EXT2 gene mutations in two pedigrees affected with hereditary multiple exostosis (HME). METHODS: The coding regions and exon/intron boundaries of the EXT1 and EXT2 genes were analyzed by targeted next-generation sequencing (NGS). Suspected mutations were confirmed by Sanger sequencing of the probands, their family members and 200 unrelated healthy controls. Gross deletion was confirmed by quantitative PCR (qPCR) analysis and multiple ligation-dependent probe amplification (MLPA) analysis. RESULTS: Two mutations were detected in the pedigrees, which included EXT2 gene c.337_338insG mutation in pedigree 1 and deletion of entire EXT1 in pedigree 2. Analysis of sequencing data revealed that a novel heterozygous mutation (c.337_338insG) in EXT2 gene in proband 1 and his father. The same mutation was not found among healthy family members and 200 unrelated healthy controls. As shown by NGS and MLPA analysis, proband 2 carried a heterozygous deletion of entire EXT1 gene. The same deletion was also found in her mother by qPCR. CONCLUSION Mutations of the EXT1 and EXT2 genes probably underlie the HME in both pedigrees. NGS combined with Sanger sequencing, qPCR and MLPA is effective for attaining the diagnosis.
DNA Mutational Analysis ; Exostoses, Multiple Hereditary ; genetics ; Female ; Humans ; Mutation ; N-Acetylglucosaminyltransferases ; genetics ; Pedigree

OBJECTIVETo identify the genetic cause for a Chinese Han family affected with hereditary multiple osteochondromas.

METHODSTwo patients, five unaffected relatives of the family and 100 unrelated healthy controls were collected. The coding sequences and intron/exon boundaries of EXT1 gene were amplified with polymerase chain reaction (PCR) and sequenced.

RESULTSA heterozygous c.600G>A (p.Trp200X) mutation in exon 1 of the EXT1 gene was detected in the patients. The same mutation was not found in unaffected family members and 100 healthy controls.

CONCLUSIONThe hereditary multiple osteochondromas in the family is caused by a nonsense mutation (p.Trp200X) in the EXT1 gene.

Asian Continental Ancestry Group ; genetics ; Child ; Exostoses, Multiple Hereditary ; diagnosis ; genetics ; Female ; Heterozygote ; Humans ; Male ; Mutation ; N-Acetylglucosaminyltransferases ; genetics ; Pedigree

BACKGROUNDMultiple osteochondromas (MO), an inherited autosomal dominant disorder, is characterized by the presence of multiple exostoses on the long bones. MO is caused by mutations in the EXT1 or EXT2 genes which encode glycosyltransferases implicated in heparin sulfate biosynthesis.

METHODSIn this study, efforts were made to identify the underlying disease-causing mutations in patients from two MO families in China.

RESULTSTwo novel EXT1 gene mutations were identified and no mutation was found in EXT2 gene. The mutation c.497T > A in exon 1 of the EXT1 gene was cosegregated with the disease phenotype in family 1 and formed a stop codon at amino acid site 166. The fetus of the proband was diagnosed negative. In family 2, the mutation c.1430-1431delCC in exon 6 of the EXT1 gene would cause frameshift and introduce a premature stop codon after the reading frame being open for 42 amino acids. The fetus of this family inherited this mutation from the father.

CONCLUSIONSMutation analysis of two MO families in this study demonstrates its further application in MO genetic counseling and prenatal diagnosis.

Adult ; Asian Continental Ancestry Group ; genetics ; Child, Preschool ; Exostoses, Multiple Hereditary ; genetics ; Female ; Humans ; Male ; Mutation ; N-Acetylglucosaminyltransferases ; genetics

OBJECTIVEHereditary multiple exostoses (HME) is an autosomal dominant monogenic disorder of paraplasia ossium. Mutations in EXT1 and EXT2 have been suggested to be responsible for over 70% of HME cases. This study aimed to analyze the clinical features and pathogenic mutations in a Chinese family with HME (6 patients in 24 members of 3 generations) and to review the relative literature regarding mutations in EXT1 and EXT2 in the Chinese population.

METHODSClinical pedigree dada from a Chinese family of HME were collected and analysed. EXT gene mutations in this pedigree assessed by PCR and sequencing. Pubmed and Wanfang (a Chinese database) were searched for the literature related to gene mutations in Chinese HME patients.

RESULTSIn the pedigree analyzed, the age of onset of HME was becoming younger, the disease was becoming more severe, and the number of osteochondromas was increasing, in successive generations. A splicing mutation IVS5+1G>A, first identified in Chinese population, was found in all diseased members of this pedigree. According the currently available literature, EXT1 and EXT2 mutations have been detected in 29% (26/90) and 43% (39/90) Chinese families with HME.

CONCLUSIONSHME starts earlier and becomes more severe and extensive with each successive generation in members of the pedigree analyzed. A splicing mutation, IVS5+1G>A, of EXT1, first identified in Chinese population, may be responsible for HME in the studied pedigree. EXT1 and EXT2 mutation rates may be different between the Chinese and Western populations.

Adolescent ; Adult ; Aged ; Alternative Splicing ; Exostoses, Multiple Hereditary ; genetics ; Female ; Humans ; Male ; Middle Aged ; Mutation ; N-Acetylglucosaminyltransferases ; genetics ; Pedigree

OBJECTIVEHereditary multiple exostoses (HME) is an autosomal dominant disorder characterized by formation of benign cartilage-capped tumors (exostoses), typically located at the juxtaepiphyseal regions of long bones. It is genetically heterogeneous with at least three chromosomal loci: EXT1 on 8q24.1, EXT2 on 11p11, and EXT3 on 19p. EXT1 and EXT2 have been cloned and are responsible for over 80% of cases. A Chinese family with HME has been analyzed in the present study.

METHODSLinkage analysis was firstly performed to determine which of the three EXT genes could be the candidate gene, then mutation screening by PCR and direct sequencing was carried out.

RESULTSA novel nonsense mutation (c.1006C>T) in exon 6 of EXT2, which converts the codon CAA (Gln) to the stop codon (TAA) (Gln336X), was identified. Next, prenatal diagnosis was performed and the pregnancy was determined to be normal.

CONCLUSIONA new EXT2 nonsense mutation was found in a Chinese family with hereditary multipe exostoses. The information was used for a case of prenatal diagnosis.

Asian Continental Ancestry Group ; genetics ; Codon, Nonsense ; DNA Mutational Analysis ; Exons ; genetics ; Exostoses, Multiple Hereditary ; genetics ; Family ; Female ; Humans ; Male ; Mutation ; N-Acetylglucosaminyltransferases ; genetics ; Pedigree

OBJECTIVE: To explore the disease associated gene mutation of multiple exostoses by family analysis. METHODS: Polymerase chain reaction and DNA sequencing were used to detect the mutation hot spot regions of EXT1 and EXT2 gene, while restriction fragment length polymorphism was performed to screen the mutation. RESULTS: We found a novel heterozygous mutation c.811T ->C in EXT1 gene of patients, which resulted in the substitution of histidine for tyrosine at codon 271 in this hereditary multiple exostoses family. The mutation was not found in the unaffected family members, nor in the 100 unrelated normal individual, which was unreported before. CONCLUSION The novel mutation Y271H is the disease-causing mutation in the hereditary multiple exostoses family.
Amino Acid Substitution ; Exons ; Exostoses, Multiple Hereditary ; genetics ; Female ; Frameshift Mutation ; Histidine ; genetics ; Humans ; Male ; Mutation ; N-Acetylglucosaminyltransferases ; genetics ; Polymorphism, Restriction Fragment Length ; Tyrosine ; genetics