Identification and analysis of anovel variant of TRAPPC2 in a X-linked spondyloepiphyseal dysplasia tarda pedigree / 中华骨科杂志

Objective:To provide experimental evidence for genetic counseling and prenatal diagnosis by analyzing the clinical characteristics, screening and identification of the function of suspicious variants in a X-1inked spondyloepiphyseal dysplasia tarda (SEDT) family.Methods:The family members' medical history, general physical examination, femur, spine X-ray examination were collected. Peripheral blood samples of the family members were collected and DNA was extracted from these samples. Sequencing clinical whole exons of proband DNA by targeted gene high-throughput sequencing method, then analysis sequencing data. The suspicious mutation was confirmed in pedigree members by PCR and Sanger sequencing. Reverse transcription polymerase chain reaction (RT-PCR) experiments of total RNA from blood lymphocytes were performed. The amplification of exons 3 and 4 of the pathogenic gene were amplified and identified by agarose gel. The expression of the pathogenic gene was also detected.Results:Three affected males of the family were diagnosed with SEDT according to their clinical and radiological features. A nonsense mutation in the transport protein particle complex subunit 2 ( TRAPPC2) gene NM_001011658: c.91A>T (p.K31*) was found in the proband using whole exome sequencing. This variation was also detected in his cousin, but not in non-phenotypic members of the family. The RT-PCR result for amplification of exon 3 and 4 of peripheral blood lymphocytes was the same as those of normal controls, indicating that the mutation did not affect the splicing of transcripts. qPCR results showed that the transcriptional expression of TRAPPC2 in patients was significantly lower than that in family normal controls and normal people controls. Conclusion:Identification of the novel nonsense mutation (c.91A>T) in the SEDT family enables early patients screening, carrier detection, genetic counseling, prenatal diagnosis, and clinical prevention and treatment. The detailed genotype/phenotype descriptions contribute to the SEDT mutation spectrum. The study of the function of TRAPPC2 mutation will help to further elucidate the role of sedlin in cartilage.

Dihydroorotate dehydrogenase mutations lead to changes of protein and function in Miller syndrome / 重庆医学

Objective To observe the changes of corresponding proteins and function based on known clinical dihydroorotate dehydrogenase(DHODH) mutation types,i.e.,G202A,R346W and R135C in the patients with Miller syndrome.Methods HeLacell lines stably expressing Miller syndrome pathogenic mutation types G202A,R346W and R135C were established.Then the mitochondrial localization function,protein stability and enzyme activity of corresponding proteins were studied by the immunohistochemistry and mitochondrial layered positioning.Results The mitochondrial localization function of 3 kinds of DHODH mutation were not affected,which existed in the mitochondrial inner membrane after expression.The mutant G202A and R346W protein stability was reduced;the mutant R135C protein was stable,but base induced enzyme activity injury caused the deficiency of corresponding enzymatic activity.Conclusion The DHODH function injury may be related with the symptoms in Miller syndrome.

Mutation analysis of the ADAR1 gene in a pedigree with dyschromatosis symmetrica hereditaria / 中华皮肤科杂志

Objective To detect mutations in the ARAD1 gene in a pedigree with dyschromatosis symmetrica hereditaria (DSH).Methods Genomic DNA was extracted from the peripheral blood of 8 family members (including 5 patients with DSH and 3 unaffected members) in the pedigree with DSH,as well as 100 unrelated healthy controls.All the 15 exon sequences of the ADAR1 gene were amplified by polymerase chain reaction (PCR)followed by direct sequencing.Then,mutations were detected in comparison with the standard sequence of the ADAR1 gene in Genebank.Results A nonsense mutation C.1420C ＞ T (p.Arg474X) was identified at position 1 420 in exon 2 of the ADAR1 gene in the 5 patients with DSH,but not in the 3 unaffected members or 100 unrelated healthy controls.Conclusion The nonsense mutation C.1420C ＞ T in the ADAR1 gene is the causative mutation in the pedigree with DSH.

Síndrome de Marfan, mutaciones nuevas y modificadoras del gen FBN1 / Síndrome de Marfan, mutaciones nuevas y modificadoras del gen FBN1

El síndrome de Marfan (SM) es un trastorno sistémico causado por mutaciones en la proteína de la matriz extracelular fibrilina 1 (FBN1). Con un patrón de herencia autosómico dominante, los pacientes se caracterizan por presentar compromiso ocular, cardiovascular y esquelético dentro de un espectro clínico variable. Se ha sugerido que la variabilidad fenotípica intrafamiliar e interfamiliar característica del síndrome ocurre por la asociación de otras mutaciones denominadas modificadoras (driver mutations). Si bien hay claridad acerca de la causalidad genética clásica de la enfermedad, las mutaciones modificadoras descritas recientemente aún no están bien dilucidadas. Se presenta un caso de SM con una mutación no descrita previamente en el gen de la fibrilina 1; se aplica la nosología de Ghent revisada y se analiza el papel de esta mutación nueva y de las mutaciones modificadoras en la génesis de la enfermedad.

Marfan syndrome (MS) is a systemic disorder caused by mutations in the extracellular matrix protein fibrillin 1 (FBN1). With a dominant autosomal pattern, MS patients are characterized by ocular, cardiovascular and skeletal involvement, all within a variable clinical spectrum. It has been suggested that the intrafamilial and interfamilial phenotypic variability, characteristic of the syndrome, occurs by the association of other mutations called driver mutations. Even though there is a clear genetic causation, the recently described driver mutations are not yet fully elucidated. We present a MS case with a mutation not previously described in the fibrilin 1 gene, applying the revised Ghent nosology and analyzing the role of this new mutation and of the driver mutations in the genesis of the disease.

Mutation analysis of the PTCH1 gene in a pedigree with nevoid basal cell carcinoma syndrome / 中华皮肤科杂志

Objective To analyze mutations in the PTCH1 gene in a pedigree with nevoid basal cell carcinoma syndrome (NBCCS).Methods Blood samples were collected from a 58-year-old male proband with NBCCS (Ⅱ 5),his brothers (Ⅱ 1 and Ⅱ 3) and son (Ⅲ4),and 50 unrelated healthy human controls.DNA was extracted from these blood samples.PCR and direct DNA sequencing were performed to determine mutation sites in the PTCH1 gene.According to the mutation sites,allele-specific oligonucleotide primers were designed and used to confirm the pathogenic mutations in this pedigree through PCR.Results A nonsense mutation (c.2137C),which leads to the substitution of CAG by TAG with the generation of a premature termination codon (Q714X),was identified in exon 14 in one allele of the PTCH1 gene in the proband and his son,but in none of the healthy human controls.Conclusion The nonsense mutation (c.2137C ＞ T) in the PTCH1 gene may be a specific mutation causing the clinical symptoms in the patient with NBCCS.

Genetic Analysis of 10 Unrelated Korean Families with p22-phox-deficient Chronic Granulomatous Disease: An Unusually Identical Mutation of the CYBA Gene on Jeju Island, Korea

Chronic granulomatous disease (CGD) is a rare hereditary disorder characterized by recurrent life-threatening bacterial and fungal infections. The underlying defect in CGD is an inability of phagocytes to produce reactive oxygen species as a result of defects in NADPH oxidase. Considering that CGD generally affects about 3-4 in 1,000,000 individuals, it is surprising that the prevalence of CGD on Jeju Island is 20.7 in 1,000,000 individuals. We performed genetic analysis on 12 patients from 10 unrelated families and found that all patients had an identical homozygous single-base substitution of C to T in exon 1 (c.7C>T) of the CYBA gene, which was expected to result in a nonsense mutation (p.Q3X). Because Jeju Island has long been a geologically isolated region, the high prevalence of CGD on Jeju Island is presumably associated with an identical mutation inherited from a common ancestor or proband.

Analysis of Mutations in COL7A1 Gene in a Hallopeau-Siemens Variant of Recessive Dystrophic Epidermolysis Bullosa / 中华皮肤科杂志

Objective To identify C0L7Al gene mutations in a family of recessive dystrophic epidermolysis bullosa (RDEB). Methods PCR and direct DNA sequencing were used to determine the mutation sites and types. PCR using allele-specific oligonucleotide primers was performed to further identify the pathogenic cause of this disease. Results The patient examined in this study was a compound heterozygote for a S48P missense mutation in exon 2 and a 3625del 11 PTC mutation in exon 27, which was a novel combination of COL7Al mutations in RDEB. Conclusion The missense mutation and the nonsense mutation in COL7Al gene are underlying causes of the Hallopeau-Siemens variant of RDEB.

A Nonsense Mutation in Transglutaminase1Gene and Loss of Enzyme Activity in a Family with Lamellar Ichthyosis / 中华皮肤科杂志

Objective To detect the activity of transglutaminase1(TGM1)and gene mutation in a family with lamellar ichthyosis.Methods Immunohistochemistry technique was used to detect the activity of transglutaminase1.Complete encoding sequences of TGM1gene were analyzed in this family by using PCR-DNA sequencing.Results No activity of transglutaminase1was detected in the proband's skin.A nonsense mutation of C604T located in exon4of TGM1gene was identified by PCR-DNA sequencing,which caused a premature termination of Q202X and a defective polypeptide truncated by615amino acids in C-terminus.A heterozygous C604T mutation was carried by both of the proband' s parents.Conclusions The proband of lamellar ichthyosis in this family shows loss of transglutaminase1activity,which is resulted from a truncated transglutaminase1coded by the homozygous mutant TGM1gene.