A study on rare compound heterozygous mutations in SERPINC1 gene and their mechanisms / 中华检验医学杂志

Objective:Molecular mechanisms underlying compound heterozygous mutations in a patient with inherited antithrombin (AT) deficiency.Methods:The proband was admitted to the First Affiliated Hospital of Wenzhou Medical University in November 2018 with a one-day history of sudden syncope and limb twitching. Peripheral venous blood was collected from the proband and members of his lineages, totaling nine persons across three generations, and a family lineage survey was conducted. AT activity (AT:A) was measured using a chromogenic substrate assay, while AT antigen (AT:Ag) was detected through an immunoturbidimetric assay. Mutation sites were identified by means of Sanger sequencing of the SERPINC1 gene, and silico tools were applied to predict the mutational conservation and hydrophobicity changes. Recombinant plasmid expression vectors were constructed and transfected into HEK293T cells for in vitro overexpression studies. The recombinant AT protein was characterized using Western Blotting, ELISA, and cellular immunofluorescence assays.Results:The proband was a 21-year-old man with type Ⅰ AT deficiency. His AT:A was 33%, along with a corresponding reduction in AT:Ag. The genetic analysis revealed there was a heterozygous insertion mutation at c.318_319insT (p.Asn107*) and a heterozygous missense mutation at c.922G>T (p.Gly308Cys) in exons 2 and 5, respectively. These mutation sites were entirely conserved among the homologous species. Additionally, hydrophobicity studies showed that the p.Gly308Cys mutation will decrease the hydrophilicity of amino acid residues 307-313. The in vitro expression studies indicated a reduction of approximately 46.98%±2.94% and 41.35%±1.48% in the amount of recombinant protein AT-G308C in transfected cell lysates and culture supernatants, respectively. Treatment with the proteasome inhibitor (MG132) restored the cytoplasmic levels of AT-G308C protein to a level similar to that of wild-type protein. However, neither cell lysate nor culture supernatant demonstrated the presence of the recombinant protein AT-N107*. Conclusions:The heterozygous insertion mutation of p.Asn107* and the heterozygous missense mutation of p.Gly308Cys have been associated with reduced AT levels in proband. The p.Asn107* heterozygous insertion mutation may initiate the degradation of mRNA via nonsense mutation-mediated mechanisms, which would remove the defective transcripts, as well as the p.The Gly308Cys heterozygous missense mutation may cause the AT protein to undergo proteasome-dependent degradation by modifying the hydrophobicity of nearby residues in the cytoplasm.

A patient with early-onset globoid cell leukodystrophy / 中国神经精神疾病杂志

We retrospectively analyzed a child with early-onset globoid cell leukodystrophy(Krabbe's disease)caused by complex heterozygous variations in the GALC gene.The girl was admitted to the hospital at the age of 4 month with main complaints of"No obvious cause of milk refusal,poor mental state,drowsiness,convulsions,fever."Brain MRI showed abnormal symmetric signals changes in bilateral cerebellar hemispheres,bilateral internal capsule hind limbs and bilateral ventricles,thin corpus callosum,myelination process lags behind the level of children of the same age.High-throughput sequencing analysis identified compound heterozygous mutations in GALC gene(NM 000153.4):c.[908+1G>A];[194G>A and the two heterozygous mutations were correspondingly inherited from his father and mother,respectively.The application of high-throughput sequencing technology can diagnose Krabbe disease efficiently and accurately,which assists in clinical identification and diagnosis.

La doble heterocigosis por la mutación común en el codón 39 (C>T) (ß0) y la deleción siciliana (δß0) 13.4 kb causa una beta-talasemia transfusión dependiente en dos pacientes costarricenses / (Double heterozygosity for the common mutation at codon 39 (C>T) (ß0) and the Sicilian (δß0) 13.4 kb deletion, causes transfusiondependent beta-thalassemia in two Costa Rican patients)

Las talasemias son desórdenes autosómicos recesivos de las cadenas de hemoglobina que poseen expresión clínica variable según el tipo de mutación o deleción. Presentamos el caso de dos jóvenes mujeres costarricenses no relacionadas entre sí y ambas diagnosticadas con la mutación común en el codón 39 (C>T) (β0) en combinación con la deleción siciliana (δβ0) 13.4 kb. La caracterización de doble heterocigota no había sido descrita antes en la literatura médica, y discutimos el significado de este genotipo que causa un defecto tipo β0 talasemia transfusión dependiente.

Thalassemia are autosomal recessive disorders of hemoglobin chains with variable clinical expression depending on the type of mutation or deletion present. We present the common codon 39(C>T) (β0) in combination with the δβ0 13.4 kb Sicilian deletion in two non-related young women from Costa Rica. We report the characterization of the compound heterozygous not previously described phenotype, and discuss the significance of this genotype combination with a transfusion dependent β0 defect Thalassemia.

A novel mutation in the ALOX12B gene in hereditary ichthyosis: pedigree analysis for a female collodion baby / 中华皮肤科杂志

Objective:To investigate pathogenic genes and inheritance patterns in 3 consecutive collodion babies in a family.Methods:The proband was diagnosed as a collodion baby due to extensive dry and chapped skin all over the body at birth. Phenotypes of the proband's parents were normal, but their first and second children presented with dry and chapped skin at birth and died a few days after birth. DNA was extracted from peripheral blood samples of the patient and her parents for whole-exome capture sequencing, and candidate mutations were verified by Sanger sequencing.Results:Compound heterozygous mutations in the ALOX12B gene were identified in the infant, including a missense mutation c.1405 C>T (p.R469w) inherited from her father and a frameshift mutation c.68_69insC (p.L24fs) inherited from her mother.Conclusions:The infant was diagnosed with hereditary ichthyosis, which was inherited in an autosomal recessive manner. The missense mutation c.1405 C>T and frameshift mutation c.68_69insC in the ALOX12B gene may contribute to the clinical phenotype of this infant, and the frameshift mutation had not been reported in China or other countries.

Mutation analysis of the COL7A1 gene in 4 cases of recessive dystrophic epidermolysis bullosa / 中华皮肤科杂志

Objective:To analyze gene mutations in and clinical phenotypes of 4 children with recessive dystrophic epidermolysis bullosa (RDEB) .Methods:Clinical data were collected from 4 children with RDEB, and DNA was extracted from peripheral blood samples of the children and their parents. A multi-gene panel targeting congenital epidermolysis bullosa was used for high-throughput sequencing. After identification of causative gene mutations, Sanger sequencing was performed to bidirectionally verify the mutations in the patients and their parents.Results:Genetic testing showed 8 compound heterozygous mutations in the COL7A1 gene in the 4 cases. Case 1 was diagnosed with moderate generalized RDEB, and inherited a paternal mutation c.7828C>T and a maternal mutation c.448G> A; case 2 was also diagnosed with moderate generalized RDEB, and inherited a paternal mutation c.3625_3635del and a maternal mutation c.2726_2728del; case 3 was diagnosed with localized RDEB, carrying a paternal mutation c.682+1G>A and an allelic mutation c.5532+1G>A, but the mutation c.5532+1G>A was not identified in the DNA extracted from the parental peripheral blood samples; case 4 was diagnosed with severe generalized RDEB, and inherited a paternal mutation c.5196delC and a maternal mutation c.500_501insAGGG. Among these mutations, c.2726_2728del and c.5196delC had not been reported previously.Conclusions:All the 4 children with RDEB carried compound heterozygous mutations in the COL7A1 gene, which may be the cause of RDEB. The phenotypes of biallelic frameshift mutation carriers appearred more severe than those of carriers of compound heterozygous mutations composed of biallelic splice site, missense and nonsense, frameshift and amino acid deletion or insertion mutations.

Mutation analysis of the PNPLA1 gene in three families with congenital ichthyosiform erythroderma / 中华皮肤科杂志

Objective:To detect gene mutations in 3 Chinese families with congenital ichthyosiform erythroderma.Methods:Exome sequencing of peripheral blood DNA was performed for 3 probands clinically diagnosed with congenital ichthyosiform erythroderma by using a gene panel targeting hereditary skin diseases to identify mutation sites. Primers were designed according to the mutation sites for PCR amplification, and Sanger sequencing was performed to verify the mutations in probands and other family members in order to identify the cause of the disease.Results:The probands 1 and 2 presented with generalized skin dryness and scaling, and polygonal dark brown scales on the extensor aspect of the lower limbs; the proband 3 mainly presented with well-circumscribed erythema, papules and scales scattered on the trunk and extremities. All probands denied family history of similar diseases. Genetic testing showed that the proband 1 carried compound heterozygous mutations c.100G>A and c.377G>A in the PNPLA1 gene, which were inherited from her mother and father respectively; the proband 2 carried compound heterozygous mutations c.320T>A and c.434T>C in the PNPLA1 gene, which were inherited from her mother and father respectively; a homozygous mutation c.1300delG was identified in the PNPLA1 gene in the proband 3. The mutations co-segregated with the disease phenotypes in the two families with compound heterozygous mutations. Among the 5 identified mutations, the two missense mutations (c.377G>A and c.320T>A) were firstly reported.Conclusion:Biallelic mutations in the PNPLA1 gene are the causative mutations responsible for autosomal recessive congenital ichthyosis in the three probands, and the newly reported mutations expand the mutation spectrum in the disease.

Analysis of two propositas with inherited hypodysfibrinogenemia / 中华检验医学杂志

Objective:To analyze the phenotype and genotype of two propositi with inherited hypodysfibrinogenaemia caused by compound heterozygous mutations, and investigate the molecular mechanism.Metheds:Two propositi and their family members(7 person in 3 generations and 10 person in 3 generations,respectively) were investigated. The activity of plasma fibrinogen (Fg:C) and thrombin time (TT) were analyzed by coagulation method, the antigen of plasma fibrinogen (Fg:Ag) was detected by immunoturbidimetry. All of the exons and flanking sequences of FGA,FGB,FGG of two propositi were amplified by PCR, followed by direct sequencing. The ClustalX-2, 1-win software was used to analyze the conservatism of mutated gene locus. PROVEAN and Mutation Taster were applied to analyze the pathogenicity of mutated amino acid. The changes of the protein spatial structure and intermolecular interaction were analyzed by Pymol.Results:Fg:C and Fg:Ag of proposita A and B were both significantly decreased (0.74 and 0.78 g/L, 0.96 and 0.94 g/L, respectively). Gene analysis revealed that proposita A and B both carried a heterozygous mutation c.2185G>A(p.AαGlu710Lys) in exon 6 of FGA. Furthermore, proposita A also carried a heterozygous mutation c.701G>T(p.γTrp208Leu) in exon 7 of FGG, and proposita B carried a heterozygous mutation c.1015A>C(p.γSer313Arg) in exon 8 of FGG. Phylogenetic analysis suggested that p.AαGlu710,p.γTrp208 and p.γSer313 were highly conserved among homologous species. All variants were predicted to be deleterious by two online bioinformatic softwares. The protein model analysis indicated that protein spatial structure and intermolecular hydrogen bonds were changed by these variants, which destroyed the stability of Fg.Conclusion:The compound heterozygous mutations of p.AαGlu710Lys and p.γTrp208Leu,p.AαGlu710Lys and p.γSer313Arg might account for the hypodysfibrinogenemia in two propositi.

Novel Pathogenic Mutation of PNPLA1 Identified in Autosomal Recessive Congenital Ichthyosis: A Case Report / 中国医学科学杂志(英文版)

Autosomal recessive congenital ichthyosis (ARCI) is characterized by being born as collodion babies, hyperkeratosis, and skin scaling. We described a collodion baby at birth with mild ectropion, eclabium, and syndactyly. Whole exome sequencing showed a compound heterozygous variant c.[56C>A], p.(Ser19X) and c.[100G>A], p.(Ala34Thr) in the PNPLA1 gene [NM_001145717; exon 1]. The protein encoded by PNPLA1 acts as a unique transacylase that specifically transfers linoleic acid from triglyceride to ω-hydroxy fatty acid in ceramide, thus giving rise to ω-O-acylceramide, a particular class of sphingolipids that is essential for skin barrier function. The variant was located in the patatin core domain of PNPLA1 and resulted in a truncated protein which could disrupt the function of the protein. This case report highlights a novel compound heterozygous mutation in PNPLA1 identified in a Chinese child.

Portador Heterozigoto Composto de Hipercolesterolemia Familiar Causada por Variantes no LDLR / Compound Heterozygous Familial Hypercholesterolemia Caused by LDLR Variants

Resumo A hipercolesterolemia familiar (HF) é uma doença genética causada por um defeito primário no gene que codifica o receptor da LDL. Mutações diferentes no mesmo gene caracterizam um heterozigoto composto, mas pouco se sabe sobre o fenótipo dos portadores. Portanto, neste estudo, descrevemos o rastreamento em cascata de uma família brasileira com essa característica. O caso-índice é um homem de 36 anos, com colesterol total (CT) de 360 mg/dL (9,3 mmol/L) e concentração de LDL-c de 259 mg/dL (6,7 mmol/L), além de xantomas de tendão de Aquiles, obesidade e pré-hipertensão. A genotipagem identificou as mutações 661G>A, 670G>A e 682G>A, no exon 4, e 919G>A, no exon 6. A mesma mutação no exon 4 foi observada no filho do caso-índice (7 anos), que também tem hipercolesterolemia e xantomas tendinosos, ao passo que a filha do caso-índice (9 anos) apresenta mutação no exon 6 e hiperlipidemia, sem xantomas. Em suma, este relato permite uma melhor compreensão acerca da base molecular da HF no Brasil, um país multirracial, onde é esperada uma população heterogênea.

Abstract Familial hypercholesterolemia (FH) is a genetic disease caused by a primary defect in the LDL-receptor gene. Distinct variants in the same gene characterize a compound heterozygote, but little is known about the phenotypes of the carriers. Therefore, herein, we describe the cascade screening of a Brazilian family with this characteristic. The index case, a 36-year-old male, had a total cholesterol level of 360 mg/dL (9.3 mmol/L) and LDL-c value of 259 mg/dL (6.7 mmol/L), in addition to Achilles tendon xanthomas, obesity and prehypertension. Genotyping identified the variants 661G>A, 670G>A, 682G>A in exon 4 and 919G>A in exon 6. The same variant in exon 4 was found in the index case's son (7-y), who also had hypercholesterolemia and xanthomas, while the index case's daughter (9-y) had the variant in exon 6 and hyperlipidemia, without xanthomas. In summary, this report allows for a better insight into the molecular basis of FH in Brazil, a multi-racial country where a heterogeneous population is expected.

Analysis of ARSA gene variant in an infant with late infantile metachromatic leukodystrophy / 中华医学遗传学杂志

Objective@#To detect pathogenic variant of ARSA gene in an infant with late infantile metachromatic leukodystrophy (MLD).@*Methods@#The male proband had an onset of walking dysfunction and seizure at 28 months. Arylsulfatase A activity of his peripheral blood leucocytes was 26.9 nmol/mg.17h, and cranial MRI showed wild symmetrical demyelination. With genomic DNA extracted from his peripheral blood sample, all coding exons and splicing sites of the ARSA gene were subjected to Sanger sequencing. PubMed Protein BLAST system was employed to analyze cross-species conservation of the mutant amino acid. Ucsf chimera software was used to analyze the impact of candidate variants on the secondary structure of the protein product. Impact of potential variants was also analyzed with software including PolyPhen-2, Mutation Taster, SIFT and PROVEAN. Whole-exome sequencing was carried out to identify additional variants which may explain the patient’s condition.@*Results@#The proband was found to harbor compound heterozygous variants of the ARSA gene [c.467G>A (p.Gly156Asp) and c. 960G>A (p.Trp320*)], neither of which was reported previously. As predicted by Ucsf chimera software, the c. 960G>A (p.Trp320*) variant may demolish important secondary structures including α-helix, β-strand and coil of the ARSA protein, causing serious damage to its structure and loss of function. The c. 467G>A (p.Gly156Asp) variant was predicted to be "probably damaging" by PolyPhen-2, Mutation Taster and SIFT software.@*Conclusion@#The patient’s condition may be attributed to the compound heterozygous c. 467G>A (p.Gly156Asp) and c. 960G>A (p.Trp320*) variants of the ARSA gene. Above results have facilitated genetic counseling and prenatal diagnosis for this family.

Analysis of CAPN3 gene mutation in a pedigree affected by limb-girdle muscular dystrophy type 2A / 中风与神经疾病杂志

@#Objective　To analyze the pathogenic CAPN3 gene mutations in a pedigree affected with limb-girdle muscular dystrophy type 2A.Methods　Genomic DNA was extracted from the peripheral blood samples collected from the proband and family members.The whole exome sequencing was used to detect the pathogenic gene in the proband.Suspected mutations were validated by Sanger sequencing.Results　The whole exome sequencing showed that the proband carried compound heterozygous mutations of c.1194-9A>G and c.1437C>T (p.ser479=).The c.1194-9A>G was inherited from his mother.The same compound heterozygous mutation was also found in other patients in the family.The proband’s sister and daughter without disease were carriers of c.1437C >T (p.ser479=),and there was no variation detected in his son-in-law.Conclusion　The compound heterozygous mutations of the CAPN3 gene were probably responsible for the limb-girdle muscular dystrophy type 2A in the family.

Analysis of extreme obesity in two pedigrees due to leptin receptor mutation / 中华内分泌代谢杂志

This study reported two women with extreme obesity who underwent metabolic surgery due to their mutations in leptin receptor (LEPR).Genomic DNA was extracted from the anticoagulant blood samples of the two patients and their parents.A panel of genes related to metabolic diseases or whole exon sequencing was screened and the results were confirmed by Sanger sequencing.This is the first time that these three mutations in LEPR were reported.Two patients complained insatiety and early-onset obesity since childhood at clinics.Patient 1 was a 39-year-old woman with height 150 cm,weight 130 kg,and BMI 57.8 kg/m2.Serum leptin level was 156.4 μg/L.A homozygous mutation of c.2317G＞T was found in exon 15 of LEPR gene in patient 1,which was descended from her father and mother respectively.Patient 2 was a 37-year-old woman with height 158 cm,weight 167 kg,and BMI 67 kg/m2.Serum leptin level was 193.4 μg/L.Genetic analysis showed compound heterozygous mutations of c.1482delT and c.1892C ＞ A.Her father showed heterozygous c.1482delT mutation,and her mother carried heterozygous c.1892C ＞ A mutation.Two patients all underwent metabolic surgery with body weight reduction of about 22 kg and 40 kg respectively after first six months.However,the follow-up studies showed that the body weight of patient 1 rebounded to pre-surgery level in two years and patient 2 did not further lose weight in the following six months.

Diagnosis of a case with mental retardation due to novel compound heterozygous variants of TRAPPC9 gene / 中华医学遗传学杂志

Objective@#To explore the genetic basis for a boy with mental retardation.@*Methods@#Clinical data and peripheral blood samples of the family were collected. Potential variants were screened by using a panel for genes associated with intellectual impairment. Suspected variants were verified by PCR and Sanger sequencing.@*Results@#The child presented with mental retardation, language delay and poor self-care. Imaging analysis showed widening of brain fissures and subarachnoid space, and dysplasia of corpus callosum. Three novel heterozygous variants, namely c. 1705T>C(p.S569P), c. 1708dupC (p.R570Pfs*80) and c. 2273delA (p.N758Tfs*22), were identified in the TRAPPC9 gene. The mother of the proband has carried the c. 1708dupC (p.R570Pfs*80) and c. 1705T>C(p.S569P) variants, while his father has carried the c. 2273delA (p.N758Tfs*22) variant.@*Conclusion@#The compound heterozygous variants of the TRAPPC9 gene probably underlie the disease in this family. Considering the clinical and genetic heterogeneity of mental retardation, genetic testing is essential for attaining diagnosis for patients with the relevant phenotype.

Pycnodysostosis caused by CTSK mutation:one pedigree study / 中华内分泌代谢杂志

The purpose of this study was to analyze the clinical characteristics of a patient with pycnodysostosis caused by cathepsin K ( CTSK ) gene mutation and his family members in order to improve the understanding of this rare diseases. A pediatric patient with pycnodysostosis was referred to us when he was eight years old. He presented with elevated bone mineral density, short stature, dentition abnormality and multiple fractures of right tibia. Next generation sequencing ( NGS) and Sanger sequencing confirmed that the proband carried carrying compound heterozygous mutations of cathepsin K(CTSK) gene, including a missense mutation c.440C>T in exon 5 (p.Ala147Val) and a deletion mutation c. 778delA in exon 6 ( p. Ser260AlafsX15) which was inherited from his father. His mother and sister did not carry the above variations. Clinically, it is necessary to differentiate pycnodysostosis from osteopetrosis and other osteosclerotic diseases.

Genetic analysis and clinical features of a pedigree affected with hereditary coagulation factor Ⅶ deficiency caused by compound heterozygotic mutations / 中华医学遗传学杂志

Objective@#To detect potential mutations of the coagulation factor Ⅶ (F7) gene in a pedigree affected with hereditary FⅦ deficiency and explore its molecular pathogenesis.@*Methods@#The FⅦ antigen (FⅦ∶Ag) was analyzed by an enzyme-linked immunosorbent assay (ELISA) method. Prothrombin time (PT), FⅦ activity (FⅦ∶C) and other coagulant parameters were quantified with an one-stage clotting assay. The F7 gene was amplified by PCR and sequenced. Mutational sites were confirmed by reverse sequencing. Impact of amino acid substitution was assessed using SIFT and PolyPhen-2 software. Structure of the mutant protein was analyzed using Swiss-pdb Viewer software based on the three-dimensional structure in the Protein Data Bank.@*Results@#The propositus had prolonged PT (36.3 s), with FⅦ∶C and FⅦ∶Ag significantly reduced to 2% and 44%, respectively. Her father, mother, younger sister and daughter had slightly prolonged PT and reduced FⅦ∶C (86%-120%). The FⅦ∶Ag of her father and younger sister were also reduced. DNA sequencing revealed that the propositus has carried compound heterozygous mutations (Lys341Glu and IVS6-1G>A) of the F7 gene. Her father and younger sister were heterozygous for the IVS6-1G>A mutation, while her mother and daughter were heterozygous for the Lys341Glu mutation. Bioinformatics analysis indicated that Lys341Glu mutation may affect the stability and function of the FⅦ protein.@*Conclusion@#The Lys341Glu and IVS6-1G>A mutations probably underlie the reduced activity of FⅦ in this pedigree.

Analysis of HEXB gene mutations in an infant with Sandhoff disease / 中华医学遗传学杂志

Objective@#To detect potential mutations of HEXB gene in an infant with Sandhoff disease (SD).@*Methods@#Genomic DNA was extracted from peripheral blood sample of the infant. All coding exons (exons 1 to 14) and splicing sites of the HEXB gene were subjected to PCR amplification and direct sequencing.PubMed Protein BLAST system was employed to analyze cross-species conservation of the mutant amino acid. PubMed BLAST CD-search was performed to identify functional domains destroyed by thecandidate mutations. Impact of the mutations was analyzed with software including PolyPhen-2, Mutation Taster and SIFT. Whole-exome sequencing was carried out to identify additional mutations.@*Results@#The infant was found to carry compound heterozygous mutations c. 1652G>A(p.Cys551Tyr) and c. 1389C>G (p.Tyr463*) of the HEXB gene. The c. 1389C>G (p.Tyr463*) mutation may lead to destruction of two functional domains in β subunit of the Hex protein. The c. 1652G>A(p.Cys551Tyr)mutation, unreported previously, was predicted to be probably damaging by Bioinformatic analysis.@*Conclusion@#Compound heterozygous mutations c. 1652G>A(p.Cys551Tyr) and c. 1389C>G (p.Tyr463*) in the HEXB gene probably underlie the disease in this patient.

Mutation analysis of AAAS gene in a child with Allgrove syndrome / 中华内分泌代谢杂志

Objective To study the AAAS gene mutations in a child with autosomal recessive Allgrove syndrome. Methods Clinical data were collected and blood samples were obtained from the proband of Allgrove syndrome and her parents. Genomic DNA was extracted and sequenced by PCR amplification. Subclone sequencing was performed to validate the gene mutations. The disease-causing potentials of mutation genes were evaluated by the Mutation Taster, and the target protein tertiary structure was modelled by the Swiss Model. Results A new heterozygous insertion mutation(c. 1347_1348insG) of exon 15 in the proband was identified and firstly reported. Other two reported mutations were detected, which were the heterozygous mutation c. 688C>T in the patient and her mother, and the homozygous mutation c. 855C>T in the proband and her parents. In addition, it was confirmed that the novel compound heterozygous mutations(c. 688C>T, c. 1347_1348insG) in the AAAS gene of the proband were pathogenic mutation locus. Conclusion The heterozygous mutation(c. 1347_1348insG) of AAAS gene was firstly reported. In case of the patients being clinically misdiagnosed, related-gene detection should be performed for the patients who were diagnosed with primary adrenal insufficiency during the period of infants and young childhood.

Mutation analysis of the ABCA12 gene in two families with autosomal recessive congenital ichthyosis / 中华皮肤科杂志

Objective To detect mutations of the ABCA12 gene in 2 Chinese families with autosomal recessive congenital ichthyosis (ARCI).Methods According to the typical clinical manifestations,two probands were diagnosed with ARCI.DNA was extracted from the peripheral blood samples collected from the patients and their parents.High-throughput sequencing was conducted by using multi-gene array for genetic skin disorders to determine mutation sites in the probands,and then DNA isolated from the probands and their parents were bidirectionally verified by Sanger sequencing.Results Two compound heterozygous mutations (c.2759A＞G and c.7004A＞G) in the ABCA12 gene were found in the proband 1,and another two compound heterozygous mutations (c.6163_6164insT and c.7406G＞A) were identified in the proband 2.The parents of the two probands were heterozygous carriers of one of the two mutations in the ABCA12 gene.Function prediction for the 4 mutations showed that all of the 3 missense mutations (c.2759A＞G,c.7004A＞G and c.7406G＞A) may exert pathogenic effect,and fragnin encoded by the frameshift mutation c.6163_6164insT may also affect protein function,c.2759A＞G and c.6163_6164insT were newly identified mutation sites.Conclusion The compound heterozygous mutations in the ABCA 12 gene are the causative mutations responsible for ARCI in the two probands of the two pedigrees.

Compound heterozygous mutations of CRB1 gene in a Chinese family with Leber congenital amaurosis by whole exome sequencing / 中华实验眼科杂志

Objective To investigate the disease-causing mutation in a family with Leber congenital amaurosis (LCA).Methods A Chinese Han pedigree with LCA from Chaoshan area was recruited in Shantou International Eye Center in August 2011.The clinical features of the families were evaluated,including medical history,best corrected visual acuity,intraocular pressure and fundus photography.The peripheral blood sample of 5 ml was collected from each of the family members for the extraction of genomic DNA.DNA of the proband was investigated by whole exome sequencing (WES) and was filtered for function of variants and inheritance pattern.Then,Sanger sequencing was performed to confirm the WES result on all the participating subjects in the pedigree.Results There were 11 families of 3 generations in this pedigree,and 2 female LCA patients were found (Ⅱ 2 and Ⅱ4) who were sisters.The parents (Ⅰ-1 and Ⅰ-2) and children (Ⅲ-1,Ⅲ-2,Ⅲ-3 and Ⅲ-4) of the patients showed normal phenotype,suggesting an autosomal recessive pattern.The patients appeared severe visual impairment during early childhood.Ophthalmic examination showed diffuse pigmentation on the retina and attenuation of retinal artery in both patients.WES of proband revealed two compound heterozygous mutations (c.2234C ＞T,p.T745M;c.3488G＞T,p.C1163F) of the CRB1 gene.Sanger sequencing confirmed the mutations in both patients (Ⅱ-2 and Ⅲ-4),and the parents of the patients were found to carry one mutations respectively and the other subjects with normal phenotype had neither none or only one mutation.Conclusions The compound heterozygous mutation of c.2234C＞ T,p.T745M and c.3488G＞T,p.C1163F in CRB1 is responsible for LCA pathogenesis this Chinese Han pedigree.

Novel compound heterozygous mutations of ALDH1A3 contribute to anophthalmia in a non-consanguineous Chinese family

Abstract Anophthalmia is a rare eye development anomaly resulting in absent ocular globes or tissue in the orbit since birth. Here, we investigated a newborn with bilateral anophthalmia in a Chinese family. Exome sequencing revealed that compound heterozygous mutations c.287G > A (p.(Arg96His)) and c.709G > A (p.(Gly237Arg)) of the ALDH1A3 gene were present in the affected newborn. Both mutations were absent in all of the searched databases, including 10,000 in-house Chinese exome sequences, and these mutations were confirmed as having been transmitted from the parents. Comparative amino acid sequence analysis across distantly related species revealed that the residues at positions 96 and 234 were evolutionarily highly conserved. In silico analysis predicted these changes to be damaging, and in vitro expression analysis revealed that the mutated alleles were associated with decreased protein production and impaired tetrameric protein formation. This study firstly reported that compound heterozygous mutations of the ALDH1A3 gene can result in anophthalmia in humans, thus highlighting those heterozygous mutations in ALDH1A3 should be considered for molecular screening in anophthalmia, particularly in cases from families without consanguineous relationships.