Clinical and genetic features of 5 alpha-reductase type2 deficiency caused by SRD5A2 gene variants / 中华内分泌代谢杂志

Objective:To explore the clinical and genetic characteristics of 5α-reductase 2 deficiency syndrome(5α-RD2).Methods:Retrospective analysis of three cases of 5α-RD2 to summarize clinical data. Genetic testing was conducted using chromosome karyotyping analysis, whole-exome sequencing(WES), Sanger sequencing, and bioinformatics analysis. The effect of the novel variant on the structure of the 5α-reductase was evaluated by studying the homology modeling structure using SWISSMODEL and PyMoL.Results:The patients of all three cases have social gender as female. In Case 1, a 6-year-old patient sought medical attention due to abnormal external genitalia development. In Cases 2 and 3, 15-year-old patients presented with primary amenorrhea, and they showed masculinization of secondary sexual characteristics during puberty. In all three cases, the external genitalia exhibited varying degrees of masculinization, with clitoromegaly resembling a small penis and accompanying cryptorchidism. In Case 2, an hCG stimulation test was performed, and the testosterone/dihydrotestosterone(DHT) ratio was found to be 17.4. The karyotype of all three patients was 46, XY. Whole-exome sequencing(WES) detected SRD5A2 gene variants in all cases, with genotypes being p. Gln6Ter/p.Arg227Gln, p. Gln6Ter/p.Pro250Ala, and p. Arg227Ter/p.His89Tyr, respectively. Parental validation confirmed compound heterozygous mutations in all cases. The novel variant p. Pro250Ala was identified and classified as a likely pathogenic variant according to ACMG guidelines. Protein modeling analysis indicated that this variant may affect the binding of 5α-reductase 2 to NADPH. In Case 1, male gender was chosen, and a laparoscopic bilateral orchiopexy was performed. In Case 2, female gender was chosen, and testectomy and vaginoplasty were performed. The gender selection for Case 3 has not been definitively determined yet.Conclusions:Abnormal external genitalia is a common phenotype of 5α-RD2. After hCG stimulation test, there is a significant increase in the testosterone/dihydrotestosterone(DHT) ratio, which indicates that Sanger sequencing of the SRD5A2 gene can be directly performed. 5α-RD2 exhibits significant clinical heterogeneity, and WES can facilitate the differential diagnosis of 46, XY disorders of sex development. The study also reported a novel variant, p. Pro250Ala, which enriches the SRD5A2 gene variant database.

Application of low-depth whole genome sequencing for copy number variation analysis in children with disorders of sex development / 中华医学遗传学杂志

OBJECTIVE@#To assess the value of copy number variation sequencing (CNV-seq) for the diagnosis of children with disorders of sex development (DSD).@*METHODS@#Five children with DSD who presented at the First Affiliated Hospital of Zhengzhou University from October 2019 to October 2020 were enrolled. In addition to chromosomal karyotyping, whole exome sequencing (WES), SRY gene testing, and CNV-seq were also carried out.@*RESULTS@#Child 1 and 2 had a social gender of female, whilst their karyotypes were both 46,XY. No pathogenic variant was identified by WES. The results of CNV-seq were 46,XY,+Y (1.4) and 46,XY,-Y (0.75), respectively. The remaining three children have all carried an abnormal chromosome Y. Based on the results of CNV-seq, their karyotypes were respectively verified as 45,X[60]/46,X,del(Y)(q11.221)[40], 45,X,16qh+[76]/46,X,del(Y)(q11.222),16qh+[24], and 45,X[75]/46,XY[25].@*CONCLUSION@#CNV-seq may be used to verify the CNVs on the Y chromosome among children with DSD and identify the abnormal chromosome in those with 45,X/46,XY. Above results have provided a basis for the clinical diagnosis and treatment of such children.

Genetic analysis of a rare case with Disorder of sex development due to structural rearrangement of Y chromosome / 中华医学遗传学杂志

OBJECTIVE@#To explore the genetic basis for a rare case with Disorder of sex development.@*METHODS@#Clinical data of the patient was collected. Chromosomal karyotyping, SRY gene testing, whole exome sequencing (WES), low-coverage massively parallel copy number variation sequencing (CNV-seq), fluorescence in situ hybridization (FISH), and whole genome sequencing (WGS) were carried out.@*RESULTS@#The patient, a 14-year-old female, had manifested short stature and dysplasia of second sex characteristics. She was found to have a 46,XY karyotype and positive for the SRY gene. No pathogenic variant was found by WES, except a duplication at Yp11.32q12. The result of CNV-seq was 47,XYY. FISH has confirmed mosaicism for a dicentric Y chromosome. A 23.66 Mb duplication on Yp11.32q11.223 and a 5.16 Mb deletion on Yq11.223q11.23 were found by WGS. The breakpoint was mapped at chrY: 23656267. The patient's karyotype was ultimately determined as 46,X,psu idic(Y)(q11.223)/46,X,del(Y)(q11.223).@*CONCLUSION@#The combination of multiple methods has facilitated clarification of the genetic etiology in this patient, which has provided a reference for the clinical diagnosis and treatment.

Cell-free DNA barcode-enabled single-molecule test for non-invasive prenatal diagnosis of phenylketonuria: an analysis of four cases / 中华围产医学杂志

Objective:To analyze the applicability and feasibility of a cell-free DNA barcode-enabled single-molecule test (cfBEST) in non-invasive prenatal diagnosis of phenylketonuria.Methods:This study recruited four pregnant women who were prenatally diagnosed as heterozygous carriers of hot spot mutations in the PAH gene from pedigrees with phenylketonuria at the First Affiliated Hospital of Zhengzhou University from July to September 2019. The frequency of mutations in maternal plasma cell-free DNA and the fetuses' genotypes were analyzed by cfBEST. Nested polymerase chain reaction primers were designed to amplify the mutation sites in each pedigree. The results of cfBEST were compared with those of invasive prenatal diagnosis. Descriptive analysis was used for data analysis. Results:In pedigree 1, the frequency of c.603T>G and c.842+2T>A mutations in maternal plasma cell-free DNA were 48.40% (291/601) and 9.70% (61/628), which was detected by cfBEST. The fetus was diagnosed with phenylketonuria with two heterozygous mutations. In pedigree 2, the frequency of c.1238G>C and c.842+2T>A mutations in maternal plasma cell-free DNA was 43.70% (786/1 798) and 0% (0/1 550), respectively. Both mutations were wild-type, and the fetus was neither phenylketonuria nor a carrier. In pedigree 3, the frequency of c.1045T>G and c.728G>A mutations in maternal plasma cell-free DNA was 44.00% (930/2 112) and 0% (0/705), respectively, suggesting that both mutations in the fetus were wild-type, and the fetus was neither phenylketonuria nor a carrier. In pedigree 4, the frequency of c.755G>A and c.728G>A mutations were 45.40% (743/1 637) and 4.50% (28/849), respectively, which indicated that the former was wild-type, and the latter was heterozygous; namely the fetus was a carrier of phenylketonuria. The results of cfBEST were consistent with those of invasive prenatal diagnosis. Three pedigrees (Pedigree 2, 3 and 4) continued the pregnancy to full-term, and the phenylalanine levels in the neonates were all below 120 μmol/L. No abnormalities were reported in those three infants during follow-ups at one, three, and six months after birth.Conclusions:The cfBEST could be used for non-invasive prenatal diagnosis of phenylketonuria caused by PAH gene mutation, but further studies with a larger sample size are needed.

Cytogenetic and molecular genetics of a rare case with Turner syndrome / 中华内分泌代谢杂志

Turnner syndrome is a common sex chromosome disorder. We reported a rare case with Turnner syndrome caused by abnormal number and structure of sex chromosomes. Hereby fluorescence in situ hybridization (FISH) and copy number variation by whole genome low depth sequencing (CNV-seq) were used to clarify the abnormal chromosome. This study provides a diagnostic strategy for clinicians and genetic researchers.

Genotype-phenotype and genetic analysis in five patients with Kallmann syndrome / 中华内分泌代谢杂志

To study the genotype-phenotype and genetic characteristics of Kallmann syndrome. Five patients with Kallmann syndrome were enrolled. Clinical data collection, chromosome karyotyping, whole exome sequencing (WES), and multiplex ligation-dependent probe amplification (MLPA) were used. All the five patients were males, aging from 2 months to 45 years old. Three of the five patients complained cryptorchidism, one complained gonadal dysgenesis, and one complained fasting hyperglycemia. The clinical feature was hypogonadotropic hypogonadism with anosmia, and all karyotype was 46 XY. Magnetic resonance imaging (MRI) showed undeveloped olfactory bulbs and tracts. Kallmann syndrome related gene novel variants were found in all the 5 patients. The hypoplasia of right kidney was found in a patient with c. 1795_1799del (p.Asn599Profs*66) of anosmin 1 (ANOS1) variant. Clinical heterogeneity and incomplete penetrance were seen in a patient with c. 2824A>G (p.Thr942Ala) of chromodomain helicase DNA binding protein 7 (CHD7). Besides, WES indicated a 109 bp-deletion on Xp22.31 (chrX: 8507699-8507804), which was the deletion of exon 10 on ANOS1 gene verified by MLPA. The deletion variant was inherited form his mother, and conformed to X-linked recessive inheritance. Kallmann syndrome is genetic and clinical heterogeneous. WES is helpful for early diagnosis. MLPA and genome copy number variation analysis (CNV) are also recommend if necessary.

Genetic diagnosis for a patient with Leydig cell hypoplasia caused by two novel variants of LHCGR gene / 中华医学遗传学杂志

OBJECTIVE@#To explore the genetic basis for a patient with Leydig cell hypoplasia.@*METHODS@#Whole exome sequencing was used to detect genetic variants in the patient. Suspect variants were verified by PCR and Sanger sequencing of the family members.@*RESULTS@#The patient was found to carry two novel variants, namely c.265A>T (p.Ile189Leu) and c.422T>C (p.Val141Ala), of the luteinizing hormone receptor gene (LHCGR), where were respectively inherited from her father and mother. Upon prenatal diagnosis, the fetus was found to be a heterozygous carrier of the c.265A>T (p.Ile189Leu) variant.@*CONCLUSION@#The compound heterozygous variants of c.265A>T (p.Ile189Leu) and c.422T>C (p.Val141Ala) of the LHCGR gene probably underlie the Leydig cell hypoplasia in the patient.

Phenotypic and genetic characteristics of a child with 7p15 deletion syndrome / 中华医学遗传学杂志

OBJECTIVE@#To explore the genetic basis for a child with multiple malformation and growth retardation.@*METHODS@#The child was subjected to low-coverage massively parallel copy number variation sequencing (CNV-seq) based on next generation sequencing (NGS) technique.@*RESULTS@#G-banding karyotyping analysis has found no abnormality in the boy and his parents. CNV-seq analysis discovered that the child has carried a heterozygous 4.36 Mb deletion (24 020 000-28 380 000) at 7p15.3p15.1. The same deletion was not found in either parent. The deletion has encompassed 28 OMIM genes including HOXA13, CYCS, DFNA5, HOXA11 and HOXA2. Among these, HOXA13 has been associated with distal limb deformity, hypospadias and cryptorchidism. HOXA1, HOXA3 and HOXA4 are involved in the formation of cardiac primordia and primordial tube, and HOXA2 is involved in the development of auditory system. The clinical phenotype of the child was consistent with that of 7p15 deletion syndrome.@*CONCLUSION@#Haploinsufficiency of HOXA1, HOXA2, HOXA3, HOXA4 and HOXA13 genes may underlie the clinical phenotype of the child, which is comparable to 7p15 deletion syndrome.

Non-invasive prenatal diagnosis of ectodermal dysplasia caused by EDA gene mutation: a case report / 中华围产医学杂志

We report a case of non-invasive prenatal diagnosis of fetal ectodermal dysplasia caused by EDA gene mutations. The pregnant woman underwent prenatal diagnosis at 11 gestational weeks because of a childbearing history of ectodermal dysplasia. Cell-free DNA barcode-enabled single-molecule test (cfBEST) was used to detect the ectodermal dysplasia gene mutation, and chorionic villus sampling was also performed. The cfBEST results showed that the genotype of maternal EDA gene c.340C> T(p.Gln114*) was heterozygous, while the genotype of fetal EDA was normal wild-type (C/C), which were consistent with the results of villus sampling, suggesting that cfBEST can be used for non-invasive prenatal diagnosis of ectodermal dysplasia caused by EDA gene mutation.

Genetic analysis of a case with ectodermal dysplasia using whole exome sequencing / 中华医学遗传学杂志

OBJECTIVE@#To explore the genetic cause of a patient suspected for congenital ectodermal dysplasia with repeated hyperthermia and to assess the reproductive risk for his family.@*METHODS@#Medical whole-exome sequencing (WES) were used to detect single-nucleotide variations and low-coverage massively parallel copy number variation sequencing (CNV-seq) were employed to verify suspected CNVs. PCR and real-time quantitative PCR were applied to confirm the deletion of EDA gene.@*RESULTS@#The results of WES suggested that the patient carried a hemizygous deletion for chrX:69 243 016-69 395 730. CNV-seq indicated that the patient carried a deletion of approximately 0.12 Mb on Xq13.1, which encompassed the EDA gene. The PCR results confirmed that there was a hemizygous deletion of exons 3 to 8 of the EDA gene. The same deletion was not found in his mother.@*CONCLUSION@#The congenital ectodermal dysplasia of the patient may be attributed to deletion of exons 3 to 8 of the EDA gene, which could be de novo or derive from germline mosaicism of his mother. The WES and CNV-seq are of great value for the diagnosis of rare diseases.