Study On Molecular Genetics Of Hypospadias

Objects:Hypospadias is one of the most common congenital malformation.It is a kind of abnormal position of urethral orifice caused by ventral median urethral fusion disorder,often accompanied by penile deformity.The etiology and pathogenesis of hypospadias are complex,including genetic,endocrine and environmental disruptors.External genital malformations bring great psychological pressure and economic burden to patients and their parents,so early surgical treatment is needed.However,the different causes of hypospadias have different surgical effects,it is very important to find the precise cause of hypospadias.The etiology of hypospadias is highly heterogeneous,so the clinical diagnosis of hypospadias is a great challenge.With the rapid development of genetic sequencing technology,it is possible to detect the genetic variation of hypospadias and to clarify the molecular etiology.In this study,we were to screen for pathogenic genes in hypospadias of unknown etiology by using the targeted next generation sequencing technique,and analyzed the correlation between gene mutations and clinical phenotypes.From molecular genetics,to explore the etiology of hypospadias and provide a scientific basis for clinical diagnosis and treatment.Subjects and Methods:A total of 130 patients diagnosed with hypospadias from Ruijin Hospital and Renji Hospital Affiliated to Shanghai Jiaotong University School of Medicine.We collected all patients detailed clinical data and analyzed for clinical phenotypic characteristics and laboratory examination.According to the GeneCards and Pubmed databases,we selected 105 candidate genes related to urethral development and then constructed a targeted next generation sequencing panel.130 patients were sequenced by targeted next generation sequencing panel to detect genetic variants.The pathogenic gene mutation was screened according to ACMG guidelines.The correlation between genotype and clinical phenotype was analyzed by combining clinical data with gene results.Results:In this study,targeted next-generation sequencing panel was performed on 130 patients with hypospadias.We found 25 patients carried genetic variations,of which 22 patients carried pathogenic genetic variants.There were 9 different variants involved in SRD5A2 gene mutation in 13 patients,three of which were novel sites(p.P251 S,p.R94 M and p.H90Y).Four pathogenic variants of the AR gene were found in 6 patients.There was a likely pathogenic mutation(p.W178S)of PROKR2 gene in 3 patients,two of them carrying SRD5A2 and AR gene mutations,respectively.One patient who presented with tetralogy of Fallot carried a pathogenic heterozygous mutation(p.M703L)in ZFPM2 gene.One patient carried likely pathogenic heterozygous mutation(p.H251Y)in BMP4 gene.One patient had a likely pathogenic variation of HOXD13 gene(p.G11A).One patient who presented with finger deformity carried a pathogenic heterozygous mutation(p.Q704X)in GLI3 gene.One case of hypospadias carried heterozygous variation(p.T730I)of CHD7 gene and it was assessed as VUS.Hypospadias with small penis was the most common clinical phenotype among the patients with genetic variation,accounting for 68%(17/25),followed by hypospadias with unilateral or bilateral cryptorchidism 28%(7/25)and hypospadias with small penis and cryptorchidism 4%(1/25).Conclusions:1.Among 130 children with hypospadias,25 patients(25/130,19.2%)were found to carried genetic variation.Twenty-two of them(16.9%)had pathogenic variants.Three novel variants of SRD5A2 gene were found.2.SRD5A2 gene(13/25,52%)and AR gene(6/25,24%)were the most common mutations.PROKR2 gene,ZFPM2 gene,BMP4 gene,CHD7 gene,HOXD13 gene and GLI3 gene as candidate genes,although the positive detection rate is not high,but provide a basis for the clinical diagnosis of hypospadias.3.Hypospadias with small penis,especially severe hypospadias,is the most common clinical manifestation in gene carriers in this study.Clinicians need to rule out genetic variations in these patients.4.Hypospadias children use gene panel to screen the cause of hypospadias.Part of them could find genetic variation,provide the basis for making reasonable treatment plan and genetic counseling for children.