Gabriela Guercio

Paediatric Hospital Dr. Juan P. Garrahan, Buenos Aires, Buenos Aires F.D., Argentina

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Publications (25)69.66 Total impact

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    ABSTRACT: Context: Aromatase (P450arom) is the key enzyme for estrogen biosynthesis and is encoded by the CYP19A1 gene. Since 1991, several molecular CYP19A1 gene alterations associated with P450arom deficiency have been described in both sexes. Objective: To detect CYP19A1 mutations in five aromatase deficient 46,XX patients and to describe the clinical follow-up from birth to puberty. To perform haplotype analysis associated with the high frequency c.628G>A splice mutation in Argentinean patients. Design: Sequencing of the coding and flanking intronic regions of the CYP19A1 gene in all patients and parents. Haplotype analysis of patients carrying the c.628G>A mutation. Patients: Clinical and biochemical findings in five new cases and one previously reported female aromatase-deficient patient (46,XX) are described. All patients presented with ambiguous genitalia at birth. Congenital adrenal hyperplasia due to 21-hydroxylase deficiency as well as other steroidogenic defects were ruled out. Results: Phenotypic variability among the affected patients was found during follow-up. Direct sequencing of the CYP19A1 gene from genomic DNA revealed one novel mutation (c.574C>T) in two patients. In silico analysis predicted the c.574C>T mutation to be probably damaging. Four out of six nonrelated patients presented with the c.628G>A splice mutation. Haplotype analysis showed that the c.628G>A splice mutation is associated with the same haplotype in our population. Conclusions: Increased knowledge on phenotypical variability found in female aromatase-deficient patients is useful to improve the detection rate in this disorder. In our population, a genetic founder defect has probably contributed to an increase in the incidence of the c.628G>A splice mutation.
    Journal of Clinical Endocrinology &amp Metabolism 11/2014; 100(2):jc20142967. DOI:10.1210/jc.2014-2967 · 6.31 Impact Factor
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    ABSTRACT: BackgroundIGF1R gene mutations have been associated with varying degrees of intrauterine and postnatal growth retardation, and microcephaly.Objectiveto identify and characterize IGF1R gene variations in a cohort of 28 Argentinean children suspected of having IGF-1 insensitivity, who were selected on the basis of the association of pre/postnatal growth failure and microcephaly.Methods The coding sequence and flanking intronic regions of IGF1R gene were amplified and directly sequenced. Functional characterization was performed by two in vitro assays: 1) [Methyl-3H] thymidine incorporation into DNA in fibroblast cell primary cultures from patients and controls treated with IGF-1 for 16-24 hs. 2) PI3K/Akt pathway was evaluated with phospho Akt (Ser473) STAR ELISA Kit (Millipore) in fibroblast cultures from patients and controls stimulated with IGF-1 for 10 minutes. Prepubertal clinical and GH-IGF-1 axis evaluation was followed up.ResultsWe identified three novel heterozygous missense mutations in three unrelated patients, de novo p.Arg1256Ser, de novo p.Asn359Tyr and p.Tyr865Cys. In control cells, proliferation assay showed that IGF-1significantly induced DNA synthesis at 20hs, and Akt phosphorylation assay that it significantly stimulated phosphorylation after 10 minutes (p<0.05 by ANOVA and Bonferroni Tests). However, no significant increase was observed in any of the three patient fibroblasts in both functional studies. GH therapy growth response in two patients was inconsistent.Conclusion These variations led to failure of the IGF1R function causing pre and postnatal growth retardation and microcephaly. Microcephaly should be considered in the evaluation of SGA patients, since it seems to favor the frequency of detection of IGF1R mutations.This article is protected by copyright. All rights reserved.
    Clinical Endocrinology 07/2014; 82(5). DOI:10.1111/cen.12555 · 3.35 Impact Factor
  • Medicina 08/2013; 73(4):297-302. · 0.42 Impact Factor
  • 07/2013; 50(2):127-139.
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    ABSTRACT: StAR facilitates cholesterol entry into the mitochondria as part of the transduceosome complex. Recessive mutations in the gen STAR cause classic and nonclassic congenital lipoid adrenal hyperplasia. The aim of the study was to analyze the molecular consequences of a novel heterozygous STAR mutation in a 46,XY patient with ambiguous genitalia and adrenal insufficiency. We found a de novo heterozygous IVS-2A>G STAR mutation and the reported heterozygous p.G146A SF1 polymorphism with normal CYP11A1, FDXR, FDX1, VDAC1 and TSPO genes. RT-PCR and sequencing from patient's testicular RNA showed a -exon2 transcript and the wild-type (WT) transcript. Both 37 kDa precursor and 30 kDa mature protein were detected in COS-7 cell transfected with mutant and WT plasmids. Immunofluorescence showed almost no co-localization of mitochondria and mutant protein (delta22-59StAR). Delta22-59StAR activity was 65±13% of WT. Cotransfection with WT and delta22-59StAR plasmids reduced WT activity by 62.0% ± 13.9. Novel splice-junction heterozygous STAR mutation (IVS-2A>G) resulted in the in-frame loss of amino acids 22 to 59 in the N-terminal mitochondrial targeting signal. A misfolded p.G22_L59delStAR might interfere with WT StAR activity by blocking the transduceosome complex, causing an autosomal dominant form of StAR deficiency, explaining the clinical phenotype.
    Medicina 01/2013; 73(4):297-302. · 0.42 Impact Factor
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    ABSTRACT: Context:Steroid acute regulatory (StAR) protein is a mitochondria-targeted protein that is part of the transduceosome complex crucial for transport of cholesterol to mitochondria. Recessive mutations cause classic and nonclassic congenital lipoid adrenal hyperplasia.Objective:The aim of this study was to report the clinical, hormonal, genetic, and functional data of a novel heterozygous mutation in the StAR gene found in a 46,XY patient with ambiguous genitalia and neonatal severe steroidogenic deficiency.Patient:Undetectable serum steroids with high ACTH and plasma renin activity but normal acute GnRH response were found in infancy. After gonadectomy (at 3 yr of age), serum LH and testosterone were undetectable, whereas FSH was normal but increased slowly afterward. Estrogen replacement therapy, started at 10.2 yr of age, suppressed gonadotropins (for 2 yr). However, after 1 month off estrogens, the patient showed castrated levels. At 11.9 yr old, after fludrocortisone withdrawal because of hypertension, plasma renin activity and aldosterone remained normal, suggesting mineralocorticoid recovery by a StAR-independent mechanism.Results:We found a de novo heterozygous IVS-2A>G StAR mutation and the reported heterozygous p.G146A SF1 polymorphism with normal CYP11A1, FDXR, FDX1, VDAC1, and TSPO genes. The mutant StAR transcript lacked exon 2, resulting in the in-frame loss of amino acids 22 to 59 in the N-terminal mitochondrial targeting signal. In vitro, the mutant protein exhibited reduced StAR activity in a dominant-negative manner and almost no mitochondria localization.Conclusions:A misfolded p.G22_L59del StAR might interfere with wild-type StAR activity by blocking the transduceosome complex, causing an autosomal dominant form of StAR deficiency, explaining the clinical phenotype. We speculated that estrogen might have modulated mineralocorticoid function and pubertal maturation in a human natural model lacking endogenous steroid production.
    The Journal of Clinical Endocrinology and Metabolism 11/2012; 98(1). DOI:10.1210/jc.2012-2865 · 6.31 Impact Factor
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    ABSTRACT: In humans, steroidogenic factor 1 (NR5A1/SF-1) mutations have been reported to cause gonadal dysgenesis, with or without adrenal failure, in both 46,XY and 46,XX individuals. We have previously reported extreme within-family variability in affected 46,XY patients. Even though low ovarian reserve with preserved fertility has been reported in females harboring NR5A1 gene mutations, fertility has only been observed in one reported case in affected 46,XY individuals. A kindred with multiple affected members presenting gonadal dysgenesis was studied. Four 46,XY individuals presented severe hypospadias at birth, one of them associated with micropenis and cryptorchidism. The other 3 developed spontaneous male puberty, and 1 has fathered 5 children. Four 46,XX patients presented premature ovarian failure (one of them was not available for the study) or high follicle-stimulating hormone levels. Mutational analysis of the NR5A1 gene revealed a novel heterozygous mutation, c.938G→A, predicted to cause a p.Arg313Hys amino acid change. A highly conserved amino acid of the ligand-binding domain of the mature protein is affected, predicting abnormal protein function. We confirm that preserved fertility can be observed in patients with a 46,XY disorder of sex development due to heterozygous mutations in the NR5A1 gene.
    Hormone Research in Paediatrics 08/2012; 78(2):119-26. DOI:10.1159/000338346 · 1.71 Impact Factor
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    ABSTRACT: Growth retardation is a considerable clinical problem in children with chronic kidney disease (CKD). Optimization of metabolic and nutritional parameters does not always lead to improved growth. Recombinant human growth hormone (rhGH) treatment has been used to improve height. Several studies in the literature have shown increased growth velocity, although data on the final height (FH) reached are scarce. We assessed the effect of rhGH on FH standard deviation score (SDS) in children with CKD following renal transplantation (RTx), comparing it with patients who did not receive rhGH (control group) but were treated with the same protocol and followed up in a single Center. Thirty-three patients received rhGH treatment until FH. Fourteen who refused rhGH therapy were included in the controls. Prognostic factors for FH and changes in glomerular filtration rate (GFR) during follow-up were also analyzed FH SDS in rhGH-treated patients was significantly higher than in controls (-1.88 ± 1.14 vs -3.48 ± 1.19 SDS, respectively, p <0.05). In both groups, a similar reduction in GFR was observed. Height (SDS) at onset of rhGH treatment was the only statistically significant variable useful to predict response to treatment (p = 0.001). Our findings confirm that rhGH is effective to improve FH in CKD RTx patients, without affecting kidney function.
    Pediatric Nephrology 01/2012; 27(6):1005-9. DOI:10.1007/s00467-011-2090-8 · 2.88 Impact Factor
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    ABSTRACT: To report genotype-phenotype correlation in a large cohort of patients. Study of the CYP21A2 gene in 866 unrelated chromosomes of 21-hydroxylase deficiency in Argentinean patients with classic and nonclassic (NC) forms of congenital adrenal hyperplasia (CAH). Eleven most common mutations were analysed by allele-specific polymerase chain reaction, restriction fragment length polymorphism (RFLP) or southern blot analysis. Gene sequencing was performed when no mutation was detected in one allele or the genotype-phenotype correlation was lacking. The 11-most-common-mutation screening allowed for the detection of 88·1% of affected alleles (80·3% in the NC and 95·2% in the classic forms). p.V281L, IVS2-13A/C>G (In2) and gene deletions and large gene conversions were the most prevalent mutations. In2 (35·2%) in salt wasting (SW), p.I172N (37·3%) in simple virilizing and p.V281L (54·1%) in NC CAH were the most prevalent mutations within the clinical forms. In 7/15 p.P30L mutation alleles, a chimeric CYP21A1P/CYP21A2 gene [PromCYP21A1P; p.P30L] was detected, while 6/15 represented a single-nucleotide substitution, and in 2/15 linkage with mutations, p.[P30L; V281L] and [p.P30L; IVS2-13A/C > G; p.Q318X] was found. In two SW patients, a novel nonsense mutation, p.Q41X, was observed. In three p.V281L mutation patients, the phenotype was more severe than predicted by genotype. Sequence analysis revealed an intronic alteration in the allele carrying the p.V281L mutation [IVS2 + 5G > A; p.V281L]. An aberrant splicing in this p.V281L mutated allele explains the clinical phenotype. A high percentage of CYP21A2 affected alleles is detected by the 11-mutation screening study. Genotype-phenotype correlation was high, but when the phenotype is more severe than predicted by genotype, presence of two alterations in one allele should be ruled out.
    Clinical Endocrinology 05/2011; 75(4):427-35. DOI:10.1111/j.1365-2265.2011.04123.x · 3.35 Impact Factor
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    ABSTRACT: Three novel heterozygous SF-1 gene mutations affecting multiple members of two unrelated families with a history of 46,XY disorders of sex development (DSD) and 46,XX ovarian insufficiency are described. clinical and mutational analysis of the SF-1 gene in 9 subjects of two families. family 1 had 2 affected 46,XY DSD subjects. One, born with severe perineal hypospadias, was raised as a male, and presented normal adolescence. The other, born with ambiguous genitalia, uterus, and mild testicular dysgenesis, was raised as a female. A W279X heterozygous mutation and an intronic deletion (g3314-3317delTCTC (IVS 4 + 8) was found in the SF-1 gene. In family 2, 4/6 affected siblings had 46,XY DSD or hypospadias. An affected 46,XX sister had normal sexual development but increased FSH levels. The 37-year-old affected mother had entered menopause. An Y183X heterozygous mutation was detected. an extreme within-family phenotypic variability, ranging from severe prenatal undervirilization to normal pubertal development, was observed in 46,XY-affected siblings, indicating that other unknown factors might be involved in the phenotype. Low ovarian reserve and preserved fertility in 46,XX subjects can be observed in heterozygous SF-1 gene mutations.
    Hormone Research in Paediatrics 01/2011; 75(1):70-7. DOI:10.1159/000320029 · 1.71 Impact Factor
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    ABSTRACT: GH deficiency (GHD) and spine irradiation (SI) have been implicated in the mechanism of reduced adult height (AH) in childhood survivors of medulloblastoma. However, growth dynamics after tumor diagnosis and the effectiveness of rhGH on AH in comparison with rhGH-untreated survivors have not been reported. To follow height (H) SDS (HSDS) since tumor diagnosis and the effect of rhGH in GHD patients, comparing with GH-untreated GHD patients. 14 patients received rhGH treatment until AH (medulloblastoma GH-treated group, MGHGr). 19 patients refused rhGH therapy (GH-untreated control medulloblastoma group, MCGr). Standing H and sitting H (SitH) were measured. In MGHGr, mean +/- SD HSDS decreased from 0.09 +/- 0.63 at tumor diagnosis to -1.38 +/- 0.91 at diagnosis of GHD, and to -1.90 +/- 0.72 at the onset of rhGH, p < 0.01, but it remained unchanged during rhGH (AH -2.12 +/- 0.55). MCGr HSDS (-0.25 +/- 0.88) was not different from MGHGr at tumor diagnosis, but it was -3.40 +/- 0.88 at AH, significantly lower than in MGHGr, p = 0.001. SitH SDS at AH (-4.56 +/- 0.82) was significantly lower than at the onset of rhGH (-2.86 +/- 0.75), p = 0.003, and it was not different from MCGr (-4.85 +/- 1.77). rhGH treatment improves AH in GH-deficient childhood medulloblastoma survivors but not spinal growth.
    Hormone Research in Paediatrics 01/2010; 73(4):281-6. DOI:10.1159/000284393 · 1.71 Impact Factor
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    ABSTRACT: Serum IGF-I and IGFBP-3 assays are used to monitor rhGH treatment. Some discrepancies in results obtained by means of different assays have been reported. The aim of this study was to establish normal ranges for circulating IGF-I and IGFBP-3 in children and adolescents of Hispanic and Italian origin. Circulating levels of IGF-I and IGFBP-3 were measured in 169 Hispanic and Italian prepubertal children and 66 adolescents of both sexes, using a chemiluminescent assay. Serum levels of IGF-I and IGFBP-3 increased from early childhood into adolescence. After pubertal peaks of IGF-I and IGFBP-3, slight decreases were observed with increasing age. Furthermore, serum IGF-I levels were significantly higher in girls than in boys, suggesting a sexual dimorphism in serum IGF-I values in late prepuberty and early puberty. Differences in IGF-I and IGFBP-3 absolute values between our study and previous studies suggest the need to establish reference ranges for each ethnic group.
    Journal of pediatric endocrinology & metabolism: JPEM 12/2009; 22(12):1127-35. DOI:10.1515/JPEM.2009.22.12.1127 · 0.71 Impact Factor
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    ABSTRACT: Insulin resistance (IR), abnormal lipid profile, and other features of the metabolic syndrome have been described in CYP19 gene knockout mice and in aromatase-deficient adult men but not in prepubertal affected girls. To study insulin sensitivity, as well as the effects of estrogen, metformin and GnRHa treatment on glucose homeostasis, in an aromatase-deficient girl. Clinical, metabolic and hormonal follow-up data, from 8 to 12 years of age, is presented. At 9 years of age, IR (HOMA 5.6) and glucose intolerance was detected, along with high serum testosterone (2.28 nmol/l), androstenedione (4.92 nmol/l) and FSH (13.4 mIU/ml) levels. Estrogen replacement was ineffective to suppress gonadotropin and androgen levels, as well as IR. Under metformin therapy, she developed type 2 diabetes and acanthosis nigricans. GnRHa administration for 1 year resulted in marked decreases in gonadotropin and serum androgens, but severe IR persisted. Postnatal estrogen replacement and a marked decrease of endogenous androgens failed to improve IR and glucose tolerance. We propose that, in females, the increment of androgens and/or lack of estrogens during fetal life might alter the mechanism of fetal programming of insulin sensitivity.
    Hormone Research 10/2009; 72(6):370-6. DOI:10.1159/000249165 · 2.48 Impact Factor
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    ABSTRACT: INTRODUCTION: cP450aromatase deficiency provides clues for the understanding of the role of aromatase in prepubertal and pubertal human health and disease. Placental aromatization of androgens protects the female fetus against the virilizing action of fetal androgens. After birth, the dual effect of aromatase deficiency, excessive androgens, and insufficient estrogens is responsible for a variable clinical picture. Nineteen cases of aromatase gene (CYP19) deficiency have been reported. PHENOTYPE: Phenotype is dependent on sex and age. In newborns, aromatase deficiency should be considered in the etiology of 46,XX DSD, after ruling out congenital adrenal hyperplasia. In prepubertal aromatase deficient girls, high levels of ovarian androgens and gonadotropins facilitate the formation of ovarian cysts. Bone mineralization can be affected and bone aging is delayed. In pubertal girls, there is poor sexual development and abnormal virilization. The phenotype may be variable according to enzyme activity level. Insulin sensitivity may be abnormal in both men and women. Finally, aromatase might also play a role in the regulation of testicular cell mass in the newborn testis. CONCLUSION: Adequate interpretation of clinical data should lead to the analysis of the CYP19 gene for diagnostic confirmation and implementation of appropriate management.
    Hormone Research 10/2009; 72(6):321-30. DOI:10.1159/000249159 · 2.48 Impact Factor
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    ABSTRACT: Sex hormones are modulators of the GH/ IGF-I system. We have hypothesized that the inhibition of DHEAS in treated girls with congenital adrenal hyperplasia (CAH) might affect this modulation. We analyzed serum IGF-I, IGFBP-3 and DHEAS in 17 prepubertal (Pp) and 32 pubertal (Pu) girls with CAH, under hydrocortisone replacement therapy, in the presence of normal (Gr1) or high (Gr2) serum testosterone (T) and androstenedione (A) levels. All groups had appropriate normal controls. Serum DHEAS in patients with CAH was significantly lower than in the respective controls (p < 0.04), except for Pp CAH Gr2. Serum IGF-I, but not serum IGFBP-3, in CAH subgroups was significantly higher than in the respective controls (p < 0.05), except for Pp CAH Gr2. It is concluded that glucocorticoid treatment of girls with CAH results in hypofunction of the adrenal zona reticularis. Low levels of serum DHEAS could be involved in the regulation of IGF-I biological response in target tissues. Additional studies are necessary to confirm these findings.
    Journal of pediatric endocrinology & metabolism: JPEM 03/2009; 22(3):255-61. DOI:10.1515/JPEM.2009.22.3.255 · 0.71 Impact Factor
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    ABSTRACT: Adrenarche is the direct consequence of the organogenesis of the zona reticularis (ZR). Proliferation of cortical cells could take place in the outermost layers of the adrenal cortex. Cells could then migrate to differentiate the zona glomerulosa (ZG) and zona fasciculata (ZF) during fetal life, and the ZR during postnatal life. After adrenarche, there are detectable increases in circulating DHEA and DHEA-S. Adrenarche could result from an increase in 17,20-lyase activity of P450c17 secondary to high levels of cytochrome b(5) expression, and from a decrease in 3betaHSD2 expression along with an increase in the expression of SULT2A1 in the ZR. The GH-IGF system and insulin, among other factors, might also modulate adrenal androgen production. Furthermore, high concentrations of estradiol enhance basal and ACTH-stimulated DHEA-S production, while aromatase expression was observed in the human adrenal medulla but not in the ZR, suggesting that estrogens produced in the adrenal medulla might be involved in the regulation of androgen production in the ZR. Premature adrenarche might be associated with ovarian hyperandrogenism and polycystic ovarian syndrome in females, as well as with insulin resistance in both sexes. However, many questions remain, transforming adrenal androgens into markers of diseases important for human health.
    Hormone Research 10/2008; 70(5):257-67. DOI:10.1159/000157871 · 2.48 Impact Factor
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    ABSTRACT: Adrenarche is a process of postnatal sexual maturation occurring in higher primates, in which there is an increase in the secretion of adrenal androgens. It is the consequence of a process of postnatal organogenesis characterized by the development of a new zone in the adrenal cortex, the zona reticularis (ZR). The mechanism of this phenomenon remains poorly understood, suggesting that it might be a multifactorial event. A relationship between circulating IGF-I, insulin sensitivity, and adrenal androgens has been postulated. Boys and girls have different patterns of changes in insulin sensitivity at puberty, perhaps secondary to differences in the estrogen milieu. Estrogen effects may also play a role in premature adrenarche. Peripheral or local IGF-1 actions could regulate adrenal progenitor cell proliferation and migration. Since adrenal progenitor cells as well as IGF-I and the IGF-R1 are located in the outer zone of the adrenal cortex during childhood and adolescence, this peripheral cell layer, below the capsule, may contain undifferentiated progenitor cells. Therefore, the IGF-R1 signaling pathway might positively modulate the proliferation and migration of adrenal progenitor cell to stimulate the development of adrenal zones, including ZR. However, no evidence of a direct action of IGF-I on ZR was found. In addition, a role for estrogens in the ontogenesis of ZR is suggested by the presence of aromatase (CYP19) in the subcapsular zona glomerulosa and in the adrenal medulla. Estrogens produced locally could act on ZR by interacting with estrogen receptor beta (ERbeta), but not alpha, and membrane estrogen receptor GPR-30. An estradiol-induced increase in DHEA/cortisol ratio was indeed seen in cultures of adrenocortical cells from post-adrenarche adrenals. In summary, several lines of evidence point to the action of multiple factors, such as local adrenal maturational changes and peripheral metabolic signals, on postnatal human adrenal gland ZR formation.
    Reviews in Endocrine and Metabolic Disorders 10/2008; 10(1):51-61. DOI:10.1007/s11154-008-9105-1 · 3.81 Impact Factor
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    ABSTRACT: The previously described c655G>A mutation of the human cytochrome P450 aromatase gene (P450aro, CYP19) results in aberrant splicing due to disruption of a donor splice site. To explain the phenotype of partial aromatase deficiency observed in a female patient described with this mutation, molecular consequences of the c655G>A mutation were investigated. To investigate whether the c655G>A mutation causes an aberrant spliced mRNA lacking exon 5 (-Ex5), P450aro RNA was analysed from the patient's lymphocytes by reverse transcription polymerase chain reaction (RT-PCR) and by splicing assays performed in Y1 cells transfected with a P450aro -Ex5 expression vector. Aromatase activity of the c655G>A mutant was predicted by three dimensional (3D) protein modelling studies and analysed in transiently transfected Y1 cells. Exon 5 might be predicted as a poorly defined exon suggesting a susceptibility to both splicing mutations and physiological alternative splicing events. Therefore, expression of the -Ex5 mRNA was also assessed as a possibly naturally occurring alternative splicing transcript in normal human steroidogenic tissues. An aromatase deficient girl was born with ambiguous genitalia. Elevated serum LH, FSH and androgens, as well as cystic ovaries, were found during prepuberty. At the age of 8.4 years, spontaneous breast development and a 194.6 pmol/l serum oestradiol level was observed. The -Ex5 mRNA was found in lymphocytes of the P450aro deficient girl and her father, who was a carrier of the mutation. Mutant minigene expression resulted in complete exon 5 skipping. As expected from 3D protein modelling, -Ex5 cDNA expression in Y1 cells resulted in loss of P450aro activity. In addition, the -Ex5 mRNA was present in placenta, prepubertal testis and adrenal tissues. Alternative splicing of exon 5 of the CYP19 gene occurs in the wild type (WT) as well as in the c655G>A mutant. We speculate that for the WT it might function as a regulatory mechanism for aromatization, whereas for the mutant a relative prevalence of the shorter over the full-length protein might explain the phenotype of partial aromatase deficiency.
    Clinical Endocrinology 11/2007; 67(5):698-705. DOI:10.1111/j.1365-2265.2007.02948.x · 3.35 Impact Factor
  • Medicina 08/2007; 67(4):369-373. · 0.42 Impact Factor
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    ABSTRACT: P450 aromatase (P450Aro), involved in androgen to estrogen conversion, is encoded by the CYP19 gene. P450Aro c655G>A mutation described in heterozygous form in a girl and in homozygous form in an adult male with P450Aro deficiency results in an aberrant splicing due to disruption of a donor splice site. A truncated inactive protein would be expected if intron5 is retained. Surprisingly, the girl described with this mutation showed spontaneous breast development and pubertal estradiol (E2) levels suggesting residual P450Aro activity (AA). Formerly, we postulate the in frame E5 skipping as a consequence of this mutation generating a protein with some degree of activity. When P450Aro mRNA expression was analysed from patient's lymphocytes, an aberrant spliced mRNA lacking E5 (-E5mRNA) was detected, suggesting an association between E5 skipping and the presence of the mutation. Splicing assays in Y1 cells confirmed this association. -Ex5 cDNA expression in Y1 cells resulted in an inactive protein that could not explain patient's phenotype. Exon 5 might be predicted as a poorly defined exon suggesting a susceptibility to splicing mutations and physiological alternative splicing (AS) events. Therefore, -Ex5mRNA was assessed as a natural occurring alternative transcript in normal human steroidogenic tissues. As P450Aro -E5mRNA expression was detected in human term placenta, prepubertal testis and prepubertal adrenal, we might speculate that AS of P450Aro coding region would occur in humans and would be involved in the complex AA regulation. Furthermore, tissue specific regulation of AS might suggest low expression of +E5mRNA from the c655G>A allele explaining residual AA evidenced in the affected girl.
    Medicina 01/2007; 67(4):369-73. · 0.42 Impact Factor