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.

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.

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.

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 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.

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.

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.