OBJECTIVE: To explore the genetic etiology of 46 Chinese pedigrees affected with Hereditary multiple exostoses (HME) and provide genetic counseling and reproductive intervention. METHODS: Whole-exome sequencing and Sanger sequencing were carried out on 87 patients from the 46 pedigrees to analyze the variants of EXT1 and EXT2 genes. Pathogenicity of the variants was assessed based on the guidelines from the American College of Medical Genetics and Genomics and Association for Molecular Pathology (ACMG/AMP). Prenatal diagnosis and preimplantation genetic testing (PGT) were provided for couples with identified pathogenic mutations. This study was approved by the Medical Ethics Committee of the hospital (Ethics No.: LL-SC-SG-2014-010). RESULTS: In total 17 and 22 pathogenic variants were respectively identified in the EXT1 and EXT2 genes, among which 5 EXT1 and 12 EXT2 variants were unreported previously. Three patients with no family history were found to harbor de novo variants of the EXT1 gene. Twenty nine couples had opted for PGT or underwent prenatal diagnosis following natural conception, and 17 healthy babies were born. CONCLUSION This study has clarified the genetic etiology of 45 HME pedigrees and identified 17 novel variants, which has enriched the mutational spectrum of the EXT1 and EXT2 genes. Reproductive intervention through PGT and prenatal diagnosis have prevented the recurrence of HME in these families.
Humans ; Female ; Male ; Pedigree ; Exostoses, Multiple Hereditary/diagnosis* ; N-Acetylglucosaminyltransferases/genetics* ; Adult ; Exostosin 1 ; Asian People/genetics* ; Genetic Testing ; Exostosin 2 ; Mutation ; China ; Prenatal Diagnosis ; Pregnancy ; Genetic Counseling ; Preimplantation Diagnosis ; Exome Sequencing ; East Asian People

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

Cervical Vertebrae ; Exostoses, Multiple Hereditary ; Humans ; Spinal Cord Compression ; Spinal Osteophytosis

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

OBJECTIVE: To identify pathogenic variations of EXT1 and EXT2 genes in two Chinese pedigrees affected with hereditary multiple exostosis (HME). METHODS: Genomic DNA was extracted from peripheral blood samples using a phenol-chloroform method. PCR and Sanger sequencing was conducted to amplify the exons and the flanking intronic regions of the EXT1 and EXT2 genes. RESULTS: DNA sequencing has revealed a heterozygous missense variation c.812A>G (p.Tyr271Cys) in the exon 1 of EXT1 in pedigree 1, and a heterozygous frameshift variation c.1431dup (p.Ser478Leufs*43) in the exon 6 of EXT1 in the proband from pedigree 2. Both variations have co-segregated with the disease phenotype, which was also consistent with previous report. CONCLUSION Two heterozygous pathogenic variations underlying HME have been identified. The result has facilitated genetic counseling and prenatal diagnosis for the affected pedigrees.
Asian Continental Ancestry Group ; Base Sequence ; DNA Mutational Analysis ; Exostoses, Multiple Hereditary ; genetics ; pathology ; Frameshift Mutation ; Humans ; Mutation, Missense ; N-Acetylglucosaminyltransferases ; genetics ; Pedigree

Synovial chondromatosis is an uncommon disorder characterized by cartilaginous proliferation within the synovial membrane of the articular joint. Smaller joints are rarely affected and it may be progressed to osteochondromatosis after ossification or calcification of metaplastic cartilage. It is commonly presented in the third to fourth decade of life, but rarely presented in adolescence. We report a unique case of synovial osteochondromatosis of the subtalar joint in 14-year-old baseball player. Arthroscopic removal of loose body and complete excision of the osteochondral mass with concomitant synovectomy resulted in satisfactory outcome without recurrence at final follow-up.
Adolescent* ; Arthroscopy ; Baseball* ; Cartilage ; Chondromatosis, Synovial* ; Follow-Up Studies ; Humans ; Joints ; Osteochondromatosis ; Recurrence ; Subtalar Joint* ; Synovial Membrane

Heterotopic ossification of the xiphoid process is extremely rare, with only three cases previously reported. However, the surgical pathology for postoperative elongation of the xiphoid process after abdominal surgery has not yet been reported. We report a case of the postoperative elongation of the xiphoid process, 8 years after abdominal surgery for traumatic hemoperitoneum in a 53-year-old man. The patient underwent surgical excision of the elongated mass of the xiphoid process. Histopathology revealed multiple exostoses. Heterotopic ossification can occur after surgical trauma to soft or bone tissue. Surgical excision with primary closure is the treatment of choice for symptomatic heterotopic ossification.
Bone and Bones ; Exostoses ; Exostoses, Multiple Hereditary ; Hemoperitoneum ; Humans ; Middle Aged ; Ossification, Heterotopic ; Pathology, Surgical ; Xiphoid Bone

Hereditary multiple exostosis (HME) is an autosomal dominant disorder manifested by the presence of multiple osteochondromas. Although the lesions are benign in nature, exostoses are often associated with characteristic progressive skeletal deformity and displaying clinical symptoms such as mechanical irritation or impingement. We present the successful arthroscopic resection in a 24-year-old HME male with impingement syndrome and long head tendon tear of the biceps caused by osteochondroma arising from the distal clavicle.
Clavicle ; Congenital Abnormalities ; Exostoses ; Exostoses, Multiple Hereditary ; Head ; Humans ; Male ; Osteochondroma ; Shoulder Impingement Syndrome ; Shoulder ; Tears ; Tendons ; Young Adult

Multiple osteochondromas (MO) is characterized by the formation of osteochondromas throughout the entire body. Although the evidence regarding its pathogenesis is well understood, no curative treatment for the disorder is available. Patients can be treated symptomatically by surgical removal of painful osteochondromas. Unfortunately, some patients still suffer from severe pain, even after surgery. We report on a case concerning a 48-year-old woman with a history of MO who presented with persistent pain after surgical removal of a symptomatic osteochondroma of the left scapula and multiple symptomatic osteochondromas of the left foot and trochanteric region. Several interventions to reduce the pain did not have any lasting effect. Subsequently, she was treated with autologous fat grafting (AFG). After each session she was pain-free for at least one year and reported only partial recurrence of the pain. This is the first case report describing AFG for the treatment of pain after both surgical removal of an osteochondroma and symptomatic osteochondromas in a patient suffering MO with promising results. The treatment is more effective and clearly continues to remain active longer than injection therapy or pain medication. Future studies are necessary to confirm our results.
Adipose Tissue ; Exostoses, Multiple Hereditary* ; Female ; Femur ; Foot ; Health Resorts* ; Humans ; Middle Aged ; Osteochondroma ; Pain Management ; Recurrence ; Scapula ; Transplants*

OBJECTIVETo detect potential mutation of EXT1 gene in a pedigree affected with multiple osteochondroma and explore its pathogenic mechanism.

METHODSThe coding regions and their flanking sequences of the EXT1/EXT2 genes were subjected to PCR amplification and Sanger sequencing. Suspected mutations were verified by excluding possible single nucleotide polymorphisms and bioinformatics analysis. Transcripts of the EXT1 gene in the proband were analyzed by TA clone-sequencing, with its abundance compared with that of healthy controls.

RESULTSDNA sequencing has identified in the proband a novel heterozygous point mutation (c.1164+1G to A) at the 5'splice sites of intron 3 of the EXT1 gene. The same mutation was not found in the healthy controls. Bioinformatics analysis indicated that the mutation is highly conserved and can lead to skipping of exon 3 or aberrant splicing. TA clone-sequencing indicated that the numbers of transcripts with skipping of exon 3 has significantly increased in the proband (< 0.05) compared with the controls.

CONCLUSIONThe c.1164+1G to A mutation has resulted in skipping of exon 3 in a proportion of EXT1 gene transcripts. As the result, the number of transcripts with tumor suppressing function is relatively reduced and has ultimately led to the tumors.

Adult ; Base Sequence ; Child ; Exostoses, Multiple Hereditary ; genetics ; Female ; Humans ; Male ; Molecular Sequence Data ; N-Acetylglucosaminyltransferases ; genetics ; Point Mutation ; RNA Splice Sites ; RNA Splicing