| Objective :(1)Clinical studies in two families with chromosome dominant Han Basan syndrome to explore the clinical characteristics of Basan syndrome.(2)Pathogenic gene mutations in Basan syndrome families were detected by whole-genome exon sequencing combined with Sanger sequencing.(3)To further understand the genetic characteristics,pathogenic genes and pathogenesis of Basan syndrome,enrich the gene mutation database,and lay the theoretical foundation for the future gene diagnosis and gene therapy.Methods:(1)Two families with suspected Basan syndrome,proband(Ⅲ2)and 5 normal controls and proband(Ⅲ4)were selected to extract genomicDNA from peripheral blood.(2)After exon hybridization capture,the whole genome exons were sequenced by the high-throughput sequencing platform.After data interpretation and screening of pathogenic variation,the possible pathogenic genes and pathogenic variation were initially selected.(3)Verification of sequencing of exon and intron-exon splice region of the candidate gene by Sanger sequencing,including members of family 1(Ⅰ1,Ⅰ2,Ⅱ1,Ⅱ2,Ⅱ3,Ⅱ4,Ⅲ1,Ⅲ2,Ⅲ3 and Ⅲ5)and family 2(Ⅲ4 and Ⅱ7)(including probands),verify genotype co-separation from phenotype.Results:(1)Quality control of WES sequencing data for two probands in family 1 and 2 and4 in family 2 first.The detected variants were later annotated by Annovar software,including variant and gene relationship,population frequency database such as gnom AD,deleterious prediction of variants such as Revel,OMIM database,HGMD database,etc.Alignment with SNP,Indel,and CNV variants on known pathogenic genes included in the OMIM database.Both probands carried the SMARCAD1 gene,001254949 gene transcript,exon 1,cDNA 378+ 1,base G changed to base A(SMARCAD1: NM＿001254949: exon1:c.378+1G> A)at the nucleotide exon cut site,which is a candidate pathogenic variant in both families.Go to the next Sanger sequencing validation phase.(2)All patients(Ⅰ1,Ⅱ2,Ⅱ4,Ⅲ1,Ⅲ2,Ⅲ4,Ⅱ7,including two probands)in both families by Sanger sequencing contained heterozygous mutations in the c.378 + 1G> A of the SMARCAD1 gene,while normal individuals(Ⅰ2,Ⅱ1,Ⅱ3,Ⅲ3,Ⅲ5)were homozygous for c.378 + 1G.No c.378 + 1G> A mutation in SMARCAD1 gene was found in the pedigree and 100 normal controls,identifying the pathogenic gene of Basan syndrome.Conclusion:(1)Two families of Basan syndrome were reported.The clinical manifestations included congenital lack of finger and toe fingerprints with palmoplantar hypohidrosis,facial millet rash,palmoplantar keratosis,fingers,toe,nail deformity,lateral crease of palms,facial depression scar,nail carrion,and fungal infection.(2)According to the genetic pedigree analysis,the two families in this study followed the Mendelian law of inheritance,consistent with the autosomal dominant inheritance.(3)As verified by whole genome exon sequencing and Sanger sequencing,it was confirmed that the skin-specific isotype of SMARCAD1 gene was the pathogenic gene of two families with Basan syndrome,and the pathogenic mutations were SMARCAD1: NM＿001254949: exon1:c.378+1G> A. |
