Two loss-of-function ANKRD11 variants in Chinese patients with short stature and a possible molecular pathway.

KBG syndrome is a rare genetic disease characterized mainly by skeletal abnormalities, distinctive facial features, and intellectual disability. Heterozygous mutations in ANKRD11 gene, or deletion of 16q24.3 that includes ANKRD11 gene are the cause of KBG syndrome. We describe two patients presenting with short stature and partial facial features, whereas no intellectual disability or hearing loss was observed in them. Two ANKRD11 variants, c.4039_4041del (p. Lys1347del) and c.6427C > G (p. Leu2143Val), were identified in this study. Both of them were classified as variants of uncertain significance (VOUS) by ACMG/AMP guidelines and were inherited from their mothers. ANKRD11 could enhance the transactivation of p21 gene, which was identified to participate in chondrogenic differentiation. In this study, we demonstrated that the knockdown of ANKRD11 could reduce the p21-promoter luciferase activities while re-introduction of wild type ANKRD11, but not ANKRD11 variants (p. Lys1347del or p. Leu2143Val), could restore the p21 levels. Thus, our study report two loss-of-function ANKRD11 variants which might provide new insight on pathogenic mechanism that correlates ANKRD11 variants with the short stature phenotype of KBG syndrome.

Pathogenic gene screening in 91 Chinese patients with short stature of unknown etiology with a targeted next-generation sequencing panel.

BACKGROUND: Dwarfism is a common severe growth disorder, but the etiology is unclear in the majority of cases. Recombinant human growth hormone may be a treatment option, but it has limited efficacy. The currently known laboratory assays do not meet the precision requirements for clinical diagnosis. Here, we have constructed a targeted next-generation sequencing (NGS) panel of selected genes that are suspected to be associated with dwarfism for genetic screening. METHODS: Genetic screening of 91 children with short stature of unknown etiology was performed with the help of the NGS panel. All the coding regions and exon-intron boundaries of 166 genes were included in the panel. To clarify the pathogenicity of these mutations, their clinical data were reviewed and analyzed. RESULTS: The assay identified p.A72G, p.I282V, and p.P491S variants of the PTPN11 gene and a p.I437T variant of the SOS1 gene in 4 cases with Noonan syndrome. A frameshift mutation (p.D2407fs) of the ACAN gene was identified in a case of idiopathic short stature with moderately advanced bone age. A p.R904C variant of the COL2A1 gene was found in a patient, who was accordingly diagnosed with Stickler syndrome. Severe short stature without limb deformity was associated with a p.G11A variant of HOXD13. In addition, we evaluated evidence that a p.D401N variant of the COMP gene may cause multiple epiphyseal dysplasia. CONCLUSIONS: Our findings suggest that syndromes, particularly Noonan syndrome, may be overlooked due to atypical clinical features. This gene panel has been verified to be effective for the rapid screening of genetic etiologies associated with short stature and for guiding precision medicine-based clinical management.

Measurement of amino-terminal propeptide of C-type natriuretic peptide in patients with idiopathic short stature or isolated growth hormone deficiency.

OBJECTIVE: To explore the value of amino-terminal propeptide of C-type natriuretic peptide (NTproCNP) in evaluating the effectiveness of therapy with recombinant human growth hormone (rhGH) in patients with idiopathic short stature (ISS) and isolated growth hormone deficiency (IGHD). METHODS: Forty-eight prepubertal children (IGHD = 25, ISS = 23) treated for at least 1 year with rhGH were included. Insulin growth factor-1 (IGF-I) and NTproCNP serum levels were measured before starting treatment and again 6 months later. Twelve months after starting treatment, all patients were assessed and annual growth velocity (GV), height standard deviation score (HTSDS), and gain HTSDS (deltaHTSDS) were recorded. RESULTS: In the GHD group, positive relationships between GV and change of IGF-I(SDS) (deltaIGF-I(SDS)), GV and change of NTproCNP concentrations (deltaNTproCNP) were found. GH peak value was also positively associated with IGF-I(SDS) and NTproCNP before therapy and deltaIGF-I(SDS) and deltaNTproCNP were positively associated. In the ISS group, GV was associated with only deltaNTproCNP. CONCLUSIONS: NTproCNP is a novel biomarker of growth as levels increase during growth-promoting treatment. Furthermore, IGF-I is also valuable in evaluating the efficacy of rhGH therapy in short stature patients.

Characterization With Gene Mutations in Han Chinese Patients With Hypospadias and Function Analysis of a Novel AR Genevariant.

It is estimated that around 10-20% of hypospadias are caused by genetic abnormalities worldwide although the spectrum of associated genes does vary across different ethnicities. The prevalence of hypospadias among the Chinese population has been increasing the last couple of decades. However, the pathogenesis underlying the disease and its associated genetic abnormality remains unclear. Here we performed a genetic analysis of 81 children with karyotype 46, XY and the hypospadias phenotype in order to characterize the genetic components that contribute to the development of hypospadias in Chinese patients. 15 candidate genes, including sex determination genes-SOX9, SRY, NR0B1 (DAX1), NR5A1 (SF1), DHH, sex differentiation genes-AR, SRD5A2, MAMLD1, INSL3, and hypospadias-associated genes-FGF8, FGF10, BMP4, BMP7, ATF3, and MID1 were screened by using next generation sequencing. A total of 18 patients were found to have mutations identified by PCR and sequencing, including 11 cases of SRD5A2 genes, 6 cases of AR genes, and 1 case of MID1 gene, respectively. One novel missense mutation p.I817N was discovered in AR gene. Further molecular analysis found that subcellular localization of the ARI 81 7N was the same as that of wild type ARWT in the absence or presence of hormone. But it led to 50% reduction in AR-induced transcriptional activity in the presence of either the synthetic androgen R1881 or the natural ligand dihydrotestosterone. Our results indicate that SRD5A2 and AR genes are two top candidate genes associated with 46, XY hypospadias in Chinese patients. Further epidemiological and genetic analysis are still needed to further clarify the pathogenesis of hypospadias in Han Chinese patients.

Identification of gene variants in 130 Han Chinese patients with hypospadias by targeted next-generation sequencing.

BACKGROUND: Hypospadias is a common congenital malformation of male external genitalia, which mainly manifests as an abnormal urethral opening on the ventral side of the penis. The etiology and clinical phenotype of hypospadias is highly heterogeneous, and its clinical diagnosis is challenging. Currently, over 70% of patients have an unknown etiology. Here, we performed a targeted analysis of gene mutations in 130 patients with hypospadias of unknown etiology to find the precise genetic cause. METHODS: We developed a targeted next-generation sequencing (NGS) panel, encompassing the exon coding regions of 105 genes involved in external genitalia and urogenital tract development and performed sequencing analysis on 130 children with hypospadias of unknown etiology. RESULTS: In total, 25 patients with hypospadias (19.2%) were found to have 20 mutations among the nine genes involved in external genitalia and urogenital tract development, including 16 reported and four novel mutation sites. Twenty-two patients (16.9%) had diagnostic variants. Multiple genetic mutations were identified in three of the 25 patients. Hypospadias combined with micropenis was the most common phenotype (68%) in 25 patients. CONCLUSIONS: Higher frequency mutations were identified in SRD5A2 (52%) and AR (24%) in our patient cohort. Middle or posterior hypospadias with micropenis may be significant indicators of genetic variations. Polygenic inheritance may be a rare genetic cause of hypospadias.

Effects of China-made recombinant human growth hormone on the treatment of growth hormone deficiency.

OBJECTIVE: To evaluate the therapeutic effect of China-made recombinant human growth hormone (r-hGH) in children with growth hormone deficiency (GHD) and to investigate the utilities of various biochemical parameters in GHD diagnosis and treatment. METHODS: Our study comprises of 30 normal children and 71 GHD children treated with China-made r-hGH substitution therapy 0.1 IU x kg(-1) x d(-1) for 6 months. Serum insulin-like growth factor-1 (IGF-1), insulin-like growth factor binding protein 3 (IGFBP-3), bone turnover markers (Ost, ICTP), and anti-growth hormone antibody (GHAb) were detected before and after r-hGH treatment. RESULTS: After the first 3 and 6 months of treatment, growth velocities of GHD children were significantly increased (13.1 +/- 3.7 and 12.6 +/- 3.6 cm/year) compared with pretreatment values (2.9 +/- 0.8 cm/year, P < 0.01). GHD Children had obviously reduced serum levels of IGF-1, IGFBP-3, and bone turnover markers (Ost, ICTP) compared with normal controls (P < 0.01), and these biochemical parameters improved significantly after treatment (P < 0.01). Growth hormone antibodies were positive in 17 of 45 cases after treatment by binding capacity detection. The binding percentage of growth hormone antibody which was increased more than 30% after the treatment showed a negative correlation with growth velocity (P < 0.01). CONCLUSIONS: (1) The growth stimulating effect and safety were confirmed in using China-made r-hGH in the treatment of GHD children for 6 months. (2) The measurements of serum IGF-1 and IGFBP-3 may serve as useful parameters in the diagnosis of GHD. (3) Serum Ost and ICTP are useful laboratory criteria for evaluating the effect of r-hGH therapy in the early stage. (4) It is necessary to monitor serum levels of GHAb during r-hGH therapy.

[Detection of fibroblast growth factor receptor 3 gene mutation at nucleotide 1138 site in congenita achondroplasia patients].

OBJECTIVE: [corrected] To investigate the mutation at the transmembrane domain of fibroblast growth factor receptor 3 (FGFR3) nucleotide 1138 site for identifying the major pathologic mechanism of achondroplasia (ACH) and to evaluate the efficacy of denaturing gradient gel electrophoresis(DGGE) method for screening the point mutations. METHODS: The genomic DNA from 17 clinically diagnosed ACH patients where analysed by polymerase chain reaction-restriction fragment length polymorphism(PCR-RFLP) with Sfc I and Msp I restriction endonucleases and by PCR-DGGE technique for screening. RESULTS: G to A transition mutation at nucleotide 1138 was detected in 14/17 of the ACH patients as heterozygotes by PCR-RFLP with Sfc I digestion. No 1138 G to C transition was detected by Msp I digestion. All of the 14 samples with G to A mutation were also found to be positive for point mutation by PCR-DGGE. No mutation was detected in 3 negative samples by PCR-RFLP, implying that there was actually no point mutation in this amplified region. CONCLUSION: Nucleotide 1138 in transmembrane domain of FGFR3 gene is the hot point for mutation in ACH and hence its major pathologic cause. PCR-DGGE is a sensitive and reliable technique for point mutation screening, especially for the heterozygotes.

Mutation analysis of the SRD5A2, AR and SF-1 genes in 52 Chinese boys with hypospadias.

OBJECTIVES: To investigate the prevalence of genetic mutations in steroid 5α-reductase-2 (SRD5A2), androgen receptor (AR) and steroidogenic factor-1 (SF-1) in Chinese children with hypospadias, and to also explore the possible underlying molecular mechanisms of this disease. METHODS: A total of 52 boys with hypospadias were enrolled. Mutational analyses of the SRD5A2, AR and SF-1 genes were performed by direct sequencing. RESULTS: SRD5A2 gene mutations were found in 13.5% (7/52 cases), including five compound heterozygotic and two homozygotic mutations. One novel heterozygotic SF-1 gene mutation was identified in a patient with perineal hypospadias and cryptorchidism, the patient's mother also had the same mutation. No mutation was found in the AR gene. The clinical manifestations of patients with mutations in SRD5A2 or SF-1 varied. CONCLUSIONS: In Chinese patients, SRD5A2 gene mutations were, relatively, frequently associated with hypospadias. The SF-1 gene may be another candidate gene for hypospadias. In contrast, AR gene mutations are not commonly associated with this condition.

[Association of 45, X/46, XY mosaicism with disorders of sex development: the clinical analysis of 5 cases].

OBJECTIVE: To analyze clinical characteristics of children with 45, X/46, XY mosaicism and explore effective managements for them. METHOD: Five children with 45, X/46, XY mosaicism were all in puberty period, of whom, three were female and two male. The standing height, weight and sexual development were measured. The levels of sex hormones, other endocrine parameters were also determined, and imaging examinations were performed. RESULT: All the patients had disorders of sex development, of whom, 4 had short stature, and the HtSDs was -2.8 ± 1.1. The results of laboratory indexes suggested that 4 had hypergonadotropic hypogonadism, with the average level of LH (13.5 ± 5.8) IU/L and FSH (56.8 ± 37.4) IU/L. Imaging examinations revealed that 2 cases had cryptorchidism, 1 had immature uterus, 1 had testicular dysgenesis and 1 had normal testis. Three patients received rhGH treatment and 1 took gender assignment into account. CONCLUSION: Patients with mosaic 45, X/46, XY karyotypes had a wide range of phenotypic manifestations, and disorders of sex development and short stature were the main clinical features. However, the disorders of sex development varied among these patients. And the management for them depends upon many factors and needs to be individualized based on the cooperation with different clinical departments.

[Genetic mutation analysis of a kindred with a patient suffering from 17 alpha-hydroxylase/17, 20-lyase deficiency].

OBJECTIVE: To detect CYP17A1 gene mutation in a patient with 17 alpha-hydroxylase/17, 20-lyase deficiency and her family members. METHOD: Genomic DNA was extracted from the blood of the patient, her parents and twin sister. The 8 exons of CYP17A1 gene were amplified with polymerase chain reaction (PCR) and screened for mutations by sequencing. RESULT: The analysis revealed that the patient was a compound heterozygote carrying two different inherited point mutations on CYP17A1 gene. They were nt186delC on exon 1 and nt1085G > A on exon 6. This type of mutation could induce 17OHD because of complete loss of 17 alpha-hydroxylase activities. And her parents and the twin sister were carriers on CYP17A1 gene. In addition, the mutation nt186delC was a novel point mutation and it was not discovered in normal children. CONCLUSION: A new compound heterozygote carrying two different inherited point mutations on CYP17A1 gene was found, and her parents and twin sister were carriers. This is probably the first report in the world of a twin sisters of whom one is a patient with 17OHD and the other is a carrier of CYP17A1 gene mutation.

[Prader-Willi syndrome and genomic imprinting].

OBJECTIVE: Prader-Willi syndrome (PWS) is an example of a human genetic disorder that involves imprinting genes on the proximal long arm of chromosome 15 and SNRPN gene as a candidate gene for this syndrome. The purpose of this study was to show the molecular genetic defects and genomic imprinting basis in Chinese PWS patients and to evaluate the clinical applications of a differential diagnostic test for PWS. METHODS: Fluorescence in situ hybridization (FISH) and methylation-specific PCR (MSPCR) techniques were applied for 4 clinically suspected PWS patients. Using three probes, including SNRPN probe for identification of the critical locus in PWS region, D15Z1 and PML control probes for identification of the 15p arm and 15q arm, the authors detected the deletions 15q in PWS. MSPCR was based on sodium bisulfite treatment of DNA and PCR primers specific for the maternal and paternal allele. RESULTS: When hybridized with mixed probes, it was found in 2 patients that the central specific signal was absent, but both the flanking control signals were retained, indicating SNRPN gene deletion of chromosome 15q11-13. Bisulfite-modified DNA from all PWS children amplified with methylated allele-specific primer pair showed only maternal 131bp PCR product, indicating the maternal uniparental disomy (UPD15). CONCLUSION: Genomic imprinting plays an important role in the molecular pathogenesis of PWS that caused by paternal microdeletions of 15q11-q13 or maternal UPD of chromosome 15. The basic defect seemed to be an absence of function of PWS genes that are normally expressed only from the paternal chromosome 15. MSPCR is a rapid and simple PCR-based assay compared with other cyto-molecular tests and its results were consistent with the clinical diagnosis of PWS, so it seems to be a reliable diagnostic method for PWS patients who show abnormal methylation at SNRPN. The genetic differential tests for PWS are important in determining familial recurrence risk.