Maria Tereza Matias Baptista

Loss-of-Function Mutations in the Genes Encoding Prokineticin-2 or Prokineticin Receptor-2 Cause Autosomal Recessive Kallmann Syndrome

CONTEXT Physiological activation of the prokineticin pathway has a critical role in olfactory bulb morphogenesis and GnRH secretion in mice. OBJECTIVE To investigate PROK2 and PROKR2 mutations in patients with hypogonadotropic hypogonadism (HH) associated or not with olfactory abnormalities. DESIGN We studied 107 Brazilian patients with HH (63 with Kallmann syndrome and 44 with normosmic HH) and 100 control individuals. The coding regions of PROK2 and PROKR2 were amplified by PCR followed by direct automatic sequencing. RESULTS In PROK2, two known frameshift mutations were identified. Two brothers with Kallmann syndrome harbored the homozygous p.G100fsX121 mutation, whereas one male with normosmic HH harbored the heterozygous p.I55fsX56 mutation. In PROKR2, four distinct mutations (p.R80C, p.Y140X, p.L173R, and p.R268C) were identified in five patients with Kallmann syndrome and in one patient with normosmic HH. These mutations were not found in the control group. The p.R80C, p.L173R, and p.R268C missense mutations were identified in the heterozygous state in the HH patients and in their asymptomatic first-degree relatives. In addition, no mutations of FGFR1, KAL1, GnRHR, KiSS-1, or GPR54 were identified in these patients. Notably, the new nonsense mutation (p.Y140X) was identified in the homozygous state in an anosmic boy with micropenis, bilateral cryptorchidism, and high-arched palate. His asymptomatic parents were heterozygous for this severe defect. CONCLUSION We expanded the repertoire of PROK2 and PROKR2 mutations in patients with HH. In addition, we show that PROKR2 haploinsufficiency is not sufficient to cause Kallmann syndrome or normosmic HH, whereas homozygous loss-of-function mutations either in PROKR2 or PROK2 are sufficient to cause disease phenotype, in accordance with the Prokr2 and Prok2 knockout mouse models.

Nonsense mutations in FGF8 gene causing different degrees of human gonadotropin-releasing deficiency.

CONTEXT FGFR1 mutations cause isolated hypogonadotropic hypogonadism (IHH) with or without olfactory abnormalities, Kallmann syndrome, and normosmic IHH respectively. Recently, missense mutations in FGF8, a key ligand for fibroblast growth factor receptor (FGFR) 1 in the ontogenesis of GnRH, were identified in IHH patients, thus establishing FGF8 as a novel locus for human GnRH deficiency. OBJECTIVE Our objective was to analyze the clinical, hormonal, and molecular findings of two familial IHH patients due to FGF8 gene mutations. METHODS AND PATIENTS The entire coding region of the FGF8 gene was amplified and sequenced in two well-phenotyped IHH probands and their relatives. RESULTS Two unique heterozygous nonsense mutations in FGF8 (p.R127X and p.R129X) were identified in two unrelated IHH probands, which were absent in 150 control individuals. These two mutations, mapped to the core domain of FGF8, impact all four human FGF8 isoforms, and lead to the deletion of a large portion of the protein, generating nonfunctional FGF8 ligands. The p.R127X mutation was identified in an 18-yr-old Kallmann syndrome female. Her four affected siblings with normosmic IHH or delayed puberty also carried the p.R127X mutation. Additional developmental anomalies, including cleft lip and palate and neurosensorial deafness, were also present in this family. The p.R129X mutation was identified in a 30-yr-old man with familial normosmic IHH and severe GnRH deficiency. CONCLUSIONS We identified the first nonsense mutations in the FGF8 gene in familial IHH with variable degrees of GnRH deficiency and olfactory phenotypes, confirming that loss-of-function mutations in FGF8 cause human GnRH deficiency.

Novel mutations affecting SRY DNA-binding activity: the HMG box N65H associated with 46,XY pure gonadal dysgenesis and the familial non-HMG box R30I associated with variable phenotypes.

Abstract. The SRY gene (sex-determining region of the Y chromosome) initiates the process of male sex differentiation in mammalians. In humans mutations in the SRY gene have been reported to account for 10–15% of the XY sex reversal cases. We describe here two novel missense mutations in the SRY gene after the screening of 17 patients, including 3 siblings, with 46,XY gonadal dysgenesis and 4 true hermaphrodites. One of the mutations, an A to C transversion within the HMG box, causes the N65H substitution and it was found in a patient presenting 46,XY pure gonadal dysgenesis. The Escherichia coli expressed SRYN65H protein did not present DNA-binding activity in vitro. The other mutation, a G to T transversion, causes the R30I substitution. This mutation was found in affected and nonaffected members of a family, including the father, two siblings with partial gonadal dysgenesis, a phenotypic female with pure gonadal dysgenesis, and three nonaffected male siblings. The G to T base change was not found in the SRY sequence of 100 normal males screened by ASO-PCR. The R30I mutation is located upstream to the HMG box, within the 29RRSSS33 phosphorylation site. The E. coli expressed SRYR30I protein was poorly phosphorylated and consequently showed reduced DNA-binding capacity in vitro.

Inhibition of CYP21A2 Enzyme Activity Caused by Novel Missense Mutations Identified in Brazilian and Scandinavian Patients

BACKGROUND Most patients with 21-hydroxylase deficiency carry CYP21A1P-derived mutations, but an increasing number of novel and rare mutations have been reported in disease-causing alleles. OBJECTIVE Functional effects of three novel (p.G56R, p.L107R, p.L142P) and one recurrent (p.R408C) CYP21A2 mutations were investigated. The degree of enzyme impairment caused by p.H62L alone or combined to p.P453S was also analyzed. DESIGN The study included 10 Brazilian and two Scandinavian patients. To determine the deleterious role of each mutant protein, in vitro assays were performed in transiently transfected COS-1 cells. For a correct genotype-phenotype correlation, the enzymatic activities were evaluated toward the two natural substrates, 17-hydroxyprogesterone and progesterone. RESULTS Low levels of residual activities obtained for p.G56R, p.L107R, p.L142P, and p.R408C mutants classified them as classical congenital adrenal hyperplasia mutations, whereas the p.H62L showed an activity within the range of nonclassical mutations. Apparent kinetic constants for p.H62L confirmed the nonclassical classification as the substrate binding capacity was within the same magnitude for mutant and normal enzymes. A synergistic effect was observed for the allele bearing the p.H62L+p.P453S combination because it caused a significant reduction in the enzymatic activity. CONCLUSIONS We describe the functional analysis of five rare missense mutations identified in Brazilian and Scandinavian patients. The p.G56R, p.L107R, and p.L142P are reported for the first time. Most probably these novel mutations are closer to null than the p.I172N, but for the p.G56R, that might not be the case, and the p.H62L is definitely a nonclassical mutation.

Classical congenital adrenal hyperplasia due to 21-hydroxylase deficiency: a cross-sectional study of factors involved in bone mineral density.

Glucocorticoids are essential in the treatment of patients with congenital adrenal hyperplasia (CAH). The opposite actions of glucocorticoids and androgens in bone mass achievement justify a study of bone mineral density (BMD) in these patients. We evaluated BMD in patients with CAH due to classic 21-hydroxylase (CYP21A2) deficiency and investigated the involvement of clinical and laboratory factors in the BMD. This study assessed the clinical and laboratory factors involved in BMD of 45 patients at the Pediatric Unit of Endocrinology, UNICAMP, who had been diagnosed as having classical CAH due to CYP21A2 deficiency including molecular characterization. The sample consisted of 28 females and 17 males; 23 salt-wasting (SW) and 22 simple virilizing (SV) cases, with average of 9.9 years (ranges, 5.1–16.3 years) when bone densitometry was performed. The DEXA method was used for calculating the areal BMD Z score in L2–L4. The variables were analyzed with reference to the BMD for chronological age (BMD/CA), height age (BMD/HA), and bone age (BMD/BA). The mean Z score for BMD/CA was 0.08 ± 1.21 (−2.55 to 2.64); it was 0.29 ± 1.33 (−2.01 to 4.00) for BMD/HA, and −0.90 ± 1.24 (−3.41 to 1.92) for BMD/BA. The BMD/CA was significantly lower in females and in patients on treatment for a long period and of more advanced chronological age. Weight and body mass index (BMI) Z scores showed a positive correlation with advanced BA. The higher the weight and BMI Z scores, the higher the BMD/HA. The BMD/BA values were significantly higher in the group in which BA was closer to CA. The BMD/BA value was significantly lower when compared to the value obtained with height and chronological ages. Sex, duration of treatment, weight, BMI, and bone age have an effect on areal BMD in patients with CAH due to CYP21A2 deficiency, which may be underestimated when evaluated in relation to CA and HA.

Bone mineralization in Turner syndrome: a transverse study of the determinant factors in 58 patients

Abstract. Turner syndrome (TS) is characterized by the presence of an X chromosome and total or partial loss of the second sex chromosome, short stature, hypergonadotrophic hypogonadism, and a variable dysmorphic picture. Delayed puberty and estrogen deficiency are some of the determinant factors of osteoporosis in TS, but the whether or not there is an intrinsic bone defect is still obscure. The aim of this study was to evaluate the correlation of the z score of bone mineral density (BMD) with age, weight, height, karyotype, associated diseases, bone age, and estrogen therapy in TS patients. We performed a transverse study with area BMD of L2–L4 with dual-energy X-ray absorptiometry (DEXA) in 58 patients with a cytogenetic diagnosis of TS, whose ages ranged from 5 to 29 years. It was observed that 86% of the patients presented with a BMD z score below −1 SD, and 46.5% with a value below −2.5 SD. There was a significant negative association of BMD with age and height, and a positive association with weight and bone mass index (BMI) z scores. A higher BMD was observed in patients with spontaneous puberty and in those with more than 2 years of hormone replacement. In conclusion, there was a high incidence of reduced bone mass among our patients, which was influenced by weight and BMI, by the use and the time of estrogen replacement, and by the presence of spontaneous puberty.

Cardiovascular and renal anomalies in Turner syndrome

OBJECTIVE To evaluate the frequency and type of cardiovascular (CV) and renal/collecting system (R/CS) abnormalities seen in a sample of patients with Turner Syndrome (TS) and to verify the proportion of those anomalies detected only after diagnosis was established. METHODS Retrospective study of 130 patients with TS diagnosed in an outpatient setting between 1989 and 2006. The mean age at diagnosis was 11.9 years. Data were obtained by personal history of CV and R/CS disorders and by results of echocardiogram and ultrasonography of the kidneys and collecting system performed after diagnosis. RESULTS 25.6% of patients who underwent echocardiograms presented CV abnormalities. Among them, mitral regurgitation (21.4%), bicuspid aortic valve (19%) and aortic coarctation (19%) were the most frequent. R/CS anomalies were found in 29.3% of patients who underwent ultrasonography. Among them, duplication of the collecting system and hydronephrosis (25% each) and horseshoe kidney (21.2%) were the most frequent. In about 80% of cases there was no previous knowledge of these anomalies. CONCLUSION The frequency of CV and R/CS abnormalities found in this study was similar to that of previous studies, but most were found in routine exams after TS diagnosis. Thus, early detection of associated anomalies depends on early detection of TS.

Morphometry and histology of gonads from 13 children with dysgenetic male pseudohermaphroditism.

Abstract Background.—Dysgenetic male pseudohermaphroditism (DMP) is a sexual differentiation disorder characterized by bilateral dysgenetic testes, persistent mullerian structures, and cryptorchidism in individuals with a 46,XY karyotype. However, the histologic criteria for the diagnosis of DMP are poorly established. Objective.—To determine gonadal histology in children with DMP. Patients and Methods.—Between 1996 and 1998, 13 patients with DMP were evaluated on our service. The clinical diagnosis of DMP was based on a 46,XY karyotype, sex ambiguity, high levels of follicle-stimulating hormone and low levels of antimullerian hormone, a decreased testosterone response to human chorionic gonadotropin stimulation without accumulation of testosterone precursors, and the presence of mullerian structures. Molecular sequencing the HMGbox region of the SRY gene did not reveal any mutations. Biopsies were performed for 22 of 26 gonads (patient age at the time of biopsy, 16 months to 10 years). Conventional micro...

Estudo multicêntrico de pacientes brasileiros com deficiência da 21-hidroxilase: correlação do genótipo com o fenótipo

ABSTRACT Multicentric Study of Brazilian Patients With 21-Hydroxylase Defi-ciency: A Genotype-Phenotype Correlation. We analyzed the clinical and molecular data of 205 patients with thethree different clinical forms of 21-hydroxylase deficiency, in whom theclinical and molecular diagnosis were already defined. The most fre-quent mutations were I2 splice in the salt wasting form, I172N in the sim-ple virilizing and V281L in the nonclassical form, presenting similar fre-quencies as those observed in other populations. We found a lower fre-quency of 21-hydroxylase gene deletion, similar to that previously iden-tified in Argentinean and Mexican populations. Five new mutations weredescribed in our population: G424S, H28+C, Ins 1003^1004 A, R408C andIVS2-2A>G. The genotype was classified in three groups according to theimpairment of enzymatic activity observed in vitro , Group A: 0-2%, GroupB: 3-7% and Group C: >20%. Group A mutations correlated with the saltwasting form, the Group B with simple virilizing form and Group C withthe non classical form. The severity of genotype showed a positive cor-

Screening of autosomal gene deletions in patients with hypogonadotropic hypogonadism using multiplex ligation-dependent probe amplification: detection of a hemizygosis for the fibroblast growth factor receptor 1

Objective  Congenital hypogonadotropic hypogonadism with anosmia (Kallmann syndrome) or with normal sense of smell is a heterogeneous genetic disorder caused by defects in the synthesis, secretion and action of gonadotrophin‐releasing hormone (GnRH). Mutations involving autosomal genes have been identified in approximately 30% of all cases of hypogonadotropic hypogonadism. However, most studies that screened patients with hypogonadotropic hypogonadism for gene mutations did not include gene dosage methodologies. Therefore, it remains to be determined whether patients without detected point mutation carried a heterozygous deletion of one or more exons.