Publications by authors named "Marco A Rivarola"

43 Publications

Estrogens in Human Male Gonadotropin Secretion and Testicular Physiology From Infancy to Late Puberty.

Front Endocrinol (Lausanne) 2020 25;11:72. Epub 2020 Feb 25.

Endocrinology Department, Hospital de Pediatría "Prof. Dr. Juan P. Garrahan", Buenos Aires, Argentina.

Several reports in humans as well as transgenic mouse models have shown that estrogens play an important role in male reproduction and fertility. Estrogen receptor alpha (ERα) and beta (ERβ) are expressed in different male tissues including the brain. The estradiol-binding protein GPER1 also mediates estrogen action in target tissues. In human testes a minimal ERα expression during prepuberty along with a marked pubertal up-regulation in germ cells has been reported. ERβ expression was detected mostly in spermatogonia, primary spermatocytes, and immature spermatids. In Sertoli cells ERβ expression increases with age. The aromatase enzyme (cP450arom), which converts androgens to estrogens, is widely expressed in human tissues (including gonads and hypothalamus), even during fetal life, suggesting that estrogens are also involved in human fetal physiology. Moreover, cP450arom is expressed in the early postnatal testicular Leydig cells and spermatogonia. Even though the aromatase complex is required for estrogen synthesis, its biological relevance is also related to the regulation of the balance between androgens and estrogens in different tissues. Knockout mouse models of aromatase (ArKO) and estrogen receptors (ERKOα, ERKOβ, and ERKOαβ) provide an important tool to study the effects of estrogens on the male reproductive physiology including the gonadal axis. High basal serum FSH levels were reported in adult aromatase-deficient men, suggesting that estrogens are involved in the negative regulatory gonadotropin feedback. However, normal serum gonadotropin levels were observed in an aromatase-deficient boy, suggesting a maturational pattern role of estrogen in the regulation of gonadotropin secretion. Nevertheless, the role of estrogens in primate testis development and function is controversial and poorly understood. This review addresses the role of estrogens in gonadotropin secretion and testicular physiology in male humans especially during childhood and puberty.
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http://dx.doi.org/10.3389/fendo.2020.00072DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7051936PMC
March 2021

Androgen Insensitivity Syndrome: Clinical Phenotype and Molecular Analysis in a Single Tertiary Center Cohort

J Clin Res Pediatr Endocrinol 2019 02 25;11(1):24-33. Epub 2018 Sep 25.

Hospital de Pediatria Garrahan, Endocrinology Service, Buenos Aires, Argentina

Objective: The aim of this study was the molecular characterization of the gene as the cause of 46,XY disorder in our population.

Methods: We studied 41, non related, 46,XY disorder of sexual differentiation index cases, having characteristics consistent with androgen insensivity syndrome (AIS). Genomic DNA was isolated from peripheral blood leukocytes of all patients and 25 family members from 17 non-related families.

Results: The gene analysis revealed an abnormal sequence in 58.5% of the index patients. All of the complete AIS (CAIS) cases were genetically confirmed, while in the partial form (PAIS) a mutation in was detected in only 13 (43.3%). Molecular studies revealed other affected or carrier relatives in 87% of the index cases. The mutations were found spread along the whole coding sequence, with a higher prevalence in the ligand binding domain. Nine out of 23 (39%) mutations were novel. In 17% of patients with detected mutations, somatic mosaicism was detected in leucocyte DNA. In our cohort, long-term follow up gender dysphoria, raised as male or female, was not found. Finally, in suspected PAIS, the identification of mutation occurred significantly less than in CAIS patients.

Conclusion: Improved knowledge of the components of the complex and signaling network might contribute to long term outcome and genetic counseling in AIS patients.
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http://dx.doi.org/10.4274/jcrpe.galenos.2018.2018.0185DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6398199PMC
February 2019

Mutation of HSD3B2 Gene and Fate of Dehydroepiandrosterone.

Vitam Horm 2018 30;108:75-123. Epub 2018 Jun 30.

Endocrine Department, Hospital de Pediatría Garrahan, Buenos Aires, Argentina; National Scientific and Technical Research Council, Buenos Aires, Argentina. Electronic address:

3βHSD2 enzyme is crucial for adrenal and gonad steroid biosynthesis. In enzyme deficiency states, due to recessive loss-of-function HSD3B2 mutations, steroid flux is altered and clinical manifestations result. Deficiency of 3βHSD2 activity in the adrenals precludes normal aldosterone and cortisol synthesis and the alternative backdoor and 11-oxygenated C19 steroid pathways and the flooding of cortisol precursors along the Δ5 pathway with a marked rise in DHEA and DHEAS production. In gonads, it precludes normal T and estrogen synthesis. Here, we review androgen-dependent male differentiation of the external genitalia in humans and link this to female development and steroidogenesis in the developing adrenal cortex. The molecular mechanisms governing postnatal adrenal cortex zonation and ZR development were also revised. This chapter will review relevant clinical, hormonal, and genetic aspects of 3βHSD2 deficiency with emphasis on the significance of alternate fates encountered by steroid hormone precursors in the adrenal gland and gonads. Our current knowledge of the process of steroidogenesis and steroid action is derived from pathological conditions. In humans the 3βHSD2 deficiency represents a model of nature that reinforces our knowledge about the role of the steroidogenic alternative pathway in sex differentiation in both sexes. However, the physiological role of the high serum DHEAS levels in fetal life as well as after adrenarche remains to be elucidated.
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http://dx.doi.org/10.1016/bs.vh.2018.05.002DOI Listing
November 2018

Androgen Insensitivity Syndrome at Prepuberty: Marked Loss of Spermatogonial Cells at Early Childhood and Presence of Gonocytes up to Puberty.

Sex Dev 2017 24;11(5-6):225-237. Epub 2018 Jan 24.

Servicio de Endocrinología, Hospital de Pediatría 'Prof. Dr. Juan Pedro Garrahan', Buenos Aires, Argentina.

Androgen insensitivity syndrome (AIS) is a hereditary condition in patients with a 46,XY karyotype in which loss-of-function mutations of the androgen receptor (AR) gene are responsible for defects in virilization. The aim of this study was to investigate the consequences of the lack of AR activity on germ cell survival and the degree of testicular development reached by these patients by analyzing gonadal tissue from patients with AIS prior to Sertoli cell maturation at puberty. Twenty-three gonads from 13 patients with AIS were assessed and compared to 18 testes from 17 subjects without endocrine disorders. The study of the gonadal structure using conventional microscopy and the ultrastructural characteristics of remnant germ cells using electron microscopy, combined with the immunohistochemical analysis of specific germ cell markers (MAGE-A4 for premeiotic germ cells and of OCT3/4 for gonocytes), enabled us to carry out a thorough investigation of germ cell life in an androgen-insensitive microenvironment throughout prepuberty until young adulthood. Here, we show that germ cell degeneration starts very early, with a marked decrease in number after only 2 years of life, and we demonstrate the permanence of gonocytes in AIS testis samples until puberty, describing 2 different populations. Additionally, our results provide further evidence for the importance of AR signaling in peritubular myoid cells during prepuberty to maintain Sertoli and spermatogonial cell health and survival.
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http://dx.doi.org/10.1159/000486089DOI Listing
October 2018

DNA methylation is not involved in specific down-regulation of HSD3B2, NR4A1 and RARB genes in androgen-secreting cells of human adrenal cortex.

Mol Cell Endocrinol 2017 02 23;441:46-54. Epub 2016 Sep 23.

Endocrine Service-CONICET, Hospital de Pediatria Garrahan, Buenos Aires, Argentina; National Research Council of Argentina (CONICET), Argentina.

We hypothesized that DNA methylation is involved in human adrenal functional zonation. mRNAs expression and methylation pattern of RARB, NR4A1 and HSD3B2 genes in human adrenal tissues (HAT) and in pediatric virilizing adrenocortical tumors (VAT) were analyzed. For analysis of the results samples were divided into 3 age groups according to FeZ involution, pre and post-adrenarche ages. In all HAT, similar RARB mRNA was found including microdissected zona reticularis (ZR) and zona fasciculata, but HSD3B2 and NR4A1 mRNAs were lower in ZR (p < 0.05). NR4A1 and RARB promoters remained unmethylated in HAT and VAT. No adrenal zone-specific differences in NR4A1 methylation were observed. In summary, RARB was not associated with ZR-specific downregulation of HSD3B2 in postnatal human adrenocotical zonation. DNA methylation would not be involved in NR4A1 adrenocortical cell-type specific downregulation. Lack of CpG islands in HSD3B2 suggested that HSD3B2 ZR-specific downregulation would not be directly mediated by DNA methylation.
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http://dx.doi.org/10.1016/j.mce.2016.09.024DOI Listing
February 2017

Two novel heterozygous missense variations within the GLI2 gene in two unrelated Argentine patients.

Medicina (B Aires) 2016;76(4):213-8

Servicio de Endocrinología, Hospital de Pediatría Prof. Dr. Juan P. Garrahan, Buenos Aires, Argentina. E-mail:

Several heterozygous GLI2 gene mutations have been reported in patients with isolated GH deficiency (IGHD) or multiple pituitary hormone deficiency (MPHD) with or without other malformations. The primary aim of this study was to analyze the presence of GLI2 gene alterations in a cohort of patients with IGHD or MPHD and ectopic/absent posterior pituitary. The coding sequence and flanking intronic regions of GLI2 gene were amplified and directly sequenced from gDNA of 18 affected subjects and relatives. In silico tools were applied to identify the functional impact of newly found variants (Polyphen2, SIFT, Mutation Taster). We identified two novel heterozygous missense variations in two unrelated patients, p.Arg231Gln and p.Arg226Leu, located in the repressor domain of the protein. Both variations affect highly conserved amino acids of the Gli2 protein and were not found in the available databases. In silico tools suggest that these variations might be disease causing. Our study suggests that the GLI2 gene may be one of the candidate genes to analyze when an association of pituitary hormone deficiency and developmental defects in posterior pituitary gland. The highly variable phenotype found suggests the presence of additional unknown factors that could contribute to the phenotype observed in these patients.
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February 2017

Five new cases of 46,XX aromatase deficiency: clinical follow-up from birth to puberty, a novel mutation, and a founder effect.

J Clin Endocrinol Metab 2015 Feb 21;100(2):E301-7. Epub 2014 Nov 21.

Endocrinology Service (R.M., N.P.G., M.Co., G.G., M.J., P.R., D.M.W., M.Ci., M.A.R., A.B., N.S.), Laboratory of Cellular Biology and Retrovirus (C.R.), Hospital de Pediatria Garrahan, C1245AAM Buenos Aires, Argentina; Endocrine Service (G.P.), Hospital Infantil Municipal de Córdoba, 5000 Córdoba, Argentina; Endocrine Service (J.G.F.), Hospital Regional de Concepcion, CPT4146GXD Tucuman, Argentina; and Endocrine Service (M.M.), Hospital de Niños de la Santísima Trinidad de Córdoba, 5000 Córdoba, Argentina.

Context: Aromatase is the key enzyme for estrogen biosynthesis and is encoded by the CYP19A1 gene. Since 1991, several molecular CYP19A1 gene alterations associated with aromatase deficiency have been described in both sexes.

Objective: The objective of the study was to detect CYP19A1 mutations in five aromatase-deficient 46,XX patients, to describe the clinical follow-up from birth to puberty and to perform haplotype analysis associated with the high-frequency c.628G>A splice mutation in Argentinean patients.

Design: The design of the study was the 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 was also performed.

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 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.
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http://dx.doi.org/10.1210/jc.2014-2967DOI Listing
February 2015

A novel missense mutation in the HSD3B2 gene, underlying nonsalt-wasting congenital adrenal hyperplasia. new insight into the structure-function relationships of 3β-hydroxysteroid dehidrogenase type II.

J Clin Endocrinol Metab 2015 Jan;100(1):E191-6

Endocrine Service (M.S.B., M.C., R.M., N.P.G., P.R., M.M., M.A.R., A.B.), Hospital de Pediatria Garrahan, CONICET, Buenos Aires, Argentina; Biological Chemistry Department (A.T., L.A.D.), Instituto de Química Física de los Materiales Medio Ambiente y Energia (INQUIMAE)-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina.

Context: 3βHSD2 is a bifunctional microsomal NAD+-dependent enzyme crucial for adrenal and gonad steroid biosynthesis, converting Δ5-steroids to Δ4-steroids. 3βHSD2 deficiency is a rare cause of congenital adrenal hyperplasia caused by recessive loss-of-function HSD3B2 mutations.

Objective: The aim was to define the pathogenic consequences of a novel missense mutation in the HSD3B2 gene.

Patient: We report a 7-month-old 46,XX girl referred because of precocious pubarche and postnatal clitoromegaly. Hormonal profile showed inadequate glucocorticoid levels, increased 17OHP and renin levels, and very high DHEAS levels, suggestive of compensated nonsalt-losing 3βHSD2 deficiency.

Design And Results: Direct sequencing revealed a novel, homozygous, pG250V HSD3B2 mutation. In vitro analysis in intact COS-7 cells showed impaired enzymatic activity for the conversion of pregnenolone to progesterone and dehydroepiandrosterone to androstenedione (20% and 27% of WT at 6 h, respectively). G250V-3βHSD2 decreased the Vmax for progesterone synthesis without affecting the Km for pregnenolone. Western blot and immunofluorescence suggested that p.G250V mutation has no effect on the expression and intracellular localization of the mutant protein. Molecular homology modeling predicted that mutant V250 affected an L239-Q251 loop next to a β-sheet structure in the NAD+-binding domain.

Conclusions: We identified a novel p.G250V mutation of HSD3B2 which causes an incomplete loss of enzymatic activity, explaining the compensated nonsalt loss phenotype. In vitro and in silico experiments provided insight into the structure-function relationship of the 3βHSD2 protein suggesting the importance of the L239-Q251 loop for the catalytic activity of the otherwise stable 3βHSD2 enzyme.
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http://dx.doi.org/10.1210/jc.2014-2676DOI Listing
January 2015

Three novel IGF1R mutations in microcephalic patients with prenatal and postnatal growth impairment.

Clin Endocrinol (Oxf) 2015 May 7;82(5):704-11. Epub 2014 Aug 7.

Endocrinology Service, Hospital de Pediatría Garrahan, Buenos Aires, Argentina.

Background: IGF1R gene mutations have been associated with varying degrees of intrauterine and postnatal growth retardation, and microcephaly.

Objective: To 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-(3) H] thymidine incorporation into DNA in fibroblast cell primary cultures from patients and controls treated with IGF-1 for 16-24 h. 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 min. Prepubertal clinical and GH-IGF-1 axis evaluation was followed up.

Results: We 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-1 significantly induced DNA synthesis at 20 h and Akt phosphorylation assay that it significantly stimulated phosphorylation after 10 min (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, because it seems to favour the frequency of detection of IGF1R mutations.
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http://dx.doi.org/10.1111/cen.12555DOI Listing
May 2015

[Novel heterozygous mutation in the steroidogenic acute regulatory protein gene in a 46,XY patient with congenital lipoid adrenal hyperplasia].

Medicina (B Aires) 2013 ;73(4):297-302

Servicio de Endocrinología, Hospital Nacional de Pediatría Juan P. Garrahan, Buenos Aires, Argentina.

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.
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June 2014

Unique dominant negative mutation in the N-terminal mitochondrial targeting sequence of StAR, causing a variant form of congenital lipoid adrenal hyperplasia.

J Clin Endocrinol Metab 2013 Jan 21;98(1):E153-61. Epub 2012 Nov 21.

Endocrine Service, Hospital de Pediatria Garrahan, Buenos Aires C1245AAM, Argentina.

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.
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http://dx.doi.org/10.1210/jc.2012-2865DOI Listing
January 2013

Advice on the management of ambiguous genitalia to a young endocrinologist from experienced clinicians.

Semin Reprod Med 2012 Oct 8;30(5):339-50. Epub 2012 Oct 8.

Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390-8857, USA.

The birth of a child with ambiguous genitalia is a challenging and distressing event for the family and physician and one with life-long consequences. Most disorders of sexual differentiation (DSD) associated with ambiguous genitalia are the result either of inappropriate virilization of girls or incomplete virilization of boys. It is important to establish a diagnosis as soon as possible, for psychological, social, and medical reasons, particularly for recognizing accompanying life-threatening disorders such as the salt-losing form of congenital adrenal hyperplasia. In most instances, there is sufficient follow-up data so that making the diagnosis also establishes the appropriate gender assignment (infants with congenital adrenal hyperplasia, those with androgen resistance syndromes), but some causes of DSD such as steroid 5α-reductase 2 deficiency and 17β-hydroxysteroid dehydrogenase deficiency are associated with frequent change in social sex later in life. In these instances, guidelines for sex assignment are less well established.
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http://dx.doi.org/10.1055/s-0032-1324717DOI Listing
October 2012

Preserved fertility in a patient with a 46,XY disorder of sex development due to a new heterozygous mutation in the NR5A1/SF-1 gene: evidence of 46,XY and 46,XX gonadal dysgenesis phenotype variability in multiple members of an affected kindred.

Horm Res Paediatr 2012 14;78(2):119-26. Epub 2012 Aug 14.

Endocrinology Service, Hospital de Pediatría Garrahan, Buenos Aires, Argentina.

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.
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http://dx.doi.org/10.1159/000338346DOI Listing
February 2013

Age-specific thyroid hormone and thyrotropin reference intervals for a pediatric and adolescent population.

Clin Chem Lab Med 2012 Apr 19;50(5):885-90. Epub 2012 Apr 19.

Department of Endocrinology, Hospital de Pediatria Garrahan, Buenos Aires, Argentina.

Background: Establishment of reliable reference intervals remains valuable for confirming validity and advancing standardization across methods and populations. Moreover, knowledge of the measurement uncertainty (U) and of the reference change value (RCV) has important applications in clinical chemistry.

Methods: Starting from the information available in the laboratory data base (29,901 subjects) an initial selection was carried out by eliminating all subjects with a clinical or laboratory pathological report; data from 7581 0- to 20-year-old subjects (53.87% girls) remained in the study. These subjects, divided into nine age groups, were used to define reference distribution percentiles (2.5th, 50th and 97.5th) of serum thyrotropin (TSH), triiodothyronine (T3), thyroxine (T4), and free T4 (fT4), as well as U and RCV of these assays.

Results: In early infancy, T4 and fT4 values were higher than in the older age groups. Serum T4 95th percentile reference value, useful for the diagnosis of hyperthyroidism, was 142.9 in 20-year-old boys and 230.4 nmol/L in early infants and serum T3 95th percentile was 2.6 and 3.5 nmol/L, respectively, while fT4 2.5th percentile reference value, useful for the diagnosis of hypothyroidism, was 9.6 and 13.0 pmol/L, respectively. Serum TSH 97.5th percentile showed less age variation, 4.38-4.88 mIU/L. Performance of the four assays resulted in approximately 20% Us, reflecting simple and complex imprecision, trueness, analytical and functional sensitivity. RCV of serum TSH (58.6%) was larger than for thyroid hormones (28.3%-34.7%), probably due to the high biological variation of this hormone.

Conclusions: We have established reference interval for TSH and thyroid hormones, as well as Us for assessing reliability of measurements, and RCVs to alert users on the presence of clinical significant changes.
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http://dx.doi.org/10.1515/cclm-2011-0495DOI Listing
April 2012

Effectiveness of rhGH treatment on final height of renal-transplant recipients in childhood.

Pediatr Nephrol 2012 Jun 26;27(6):1005-9. Epub 2012 Jan 26.

Department of Endocrinology, Hospital de Pediatria Garrahan, Buenos Aires, Argentina.

Background: 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.

Aims: 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.

Methods: 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

Results: 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).

Conclusion: Our findings confirm that rhGH is effective to improve FH in CKD RTx patients, without affecting kidney function.
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http://dx.doi.org/10.1007/s00467-011-2090-8DOI Listing
June 2012

Steroid 21-hydroxylase gene mutational spectrum in 454 Argentinean patients: genotype-phenotype correlation in a large cohort of patients with congenital adrenal hyperplasia.

Clin Endocrinol (Oxf) 2011 Oct;75(4):427-35

Endocrinology Service, Hospital de Pediatria Garrahan, Buenos Aires, Argentina.

Objective: To report genotype-phenotype correlation in a large cohort of patients.

Context: 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).

Methods: 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.

Results: 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.

Conclusions: 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.
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http://dx.doi.org/10.1111/j.1365-2265.2011.04123.xDOI Listing
October 2011

Is BaF3 bioassay useful to identify patients with bioinactive growth hormone?

J Pediatr Endocrinol Metab 2010 Aug;23(8):783-8

Pediatric Department, University ofPavia, Italy.

We analyzed the ability of the BaF3 cell line bioassay to select patients with biologically inactive GH. We first evaluated the biological response of the Ba/F3-hGHR cells to rhGH additional doses from 10 to 5000 pg/ml. The concentration points corresponding to the linear part of the curve were selected. We then analyzed a group of sera, diluted like the standard, including the entire range of GH concentrations that can be analyzed by bioassay. The serum/standard area below the curve ratio was calculated. Serum GH immunoactivity determined by IMMULITE/GH bioactivity ratios was calculated. Our experimental data showed that GH-bioactivity/GH-immunoactivity ratios below 0.303 are indicative of a bioinactive GH molecule. This bioassay would recognize only extreme cases of GH bioinactivity, and it would not be a useful tool in the search for patients with altered forms of GH.
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http://dx.doi.org/10.1515/jpem.2010.128DOI Listing
August 2010

Three new SF-1 (NR5A1) gene mutations in two unrelated families with multiple affected members: within-family variability in 46,XY subjects and low ovarian reserve in fertile 46,XX subjects.

Horm Res Paediatr 2011 22;75(1):70-7. Epub 2010 Sep 22.

Endocrinology Service, Hospital de Pediatria Garrahan, Buenos Aires, Argentina.

Background: 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.

Methods: clinical and mutational analysis of the SF-1 gene in 9 subjects of two families.

Results: 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.

Conclusion: 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.
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http://dx.doi.org/10.1159/000320029DOI Listing
May 2011

Thyroid axis dysfunction in patients with Prader-Willi syndrome during the first 2 years of life.

Clin Endocrinol (Oxf) 2010 Oct;73(4):546-50

Endocrine Service Genetics Service, Hospital de Pediatria Garrahan, Buenos Aires, Argentina.

Introduction: Prader-Willi syndrome (PWS) is a genetic disorder caused by the loss of expression of paternally transcribed genes in a highly imprinted region of chromosome 15q11-13. The clinical phenotype has been well characterized, mostly related to hypothalamic dysfunction. Even though central hypothyroidism has been documented in 20-30% of patients with PWS, thyroid function during the first 2 years of life has not been clearly defined.

Objective: To evaluate hypothalamic-pituitary-thyroid function in infant PWS patients.

Study Design: Eighteen patients with PWS, aged 0.16-2 years, were included in a prospective study. PWS diagnosis was based on clinical features and molecular analysis. Serum total (T) T4, free (F) T4, T3 and thyroid-stimulating hormone (TSH) were evaluated in the patients with PWS included in the study. Serum hormone values were compared to those of a large reference population of the same age.

Results: In 13 of 18 patients with PWS (72.2%), serum TT4 and/or FT4 levels were below the 2.5th percentile of the reference population, while in only one PWS patient serum T3 was below this cut-off.

Conclusion: The results of this study suggest that transient or definitive thyrotropin-releasing hormone (TRH)-TSH thyroid axis dysfunction may frequently be present in infant PWS patients. Paediatricians should be aware of this dysfunction in this critical period of thyroid hormone action on neurological development.
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http://dx.doi.org/10.1111/j.1365-2265.2010.03840.xDOI Listing
October 2010

Two novel mutations of the TSH-beta subunit gene underlying congenital central hypothyroidism undetectable in neonatal TSH screening.

J Clin Endocrinol Metab 2010 Sep 9;95(9):E98-103. Epub 2010 Jun 9.

Servicio de Endocrinologia, Hospital de Pediatria Garrahan, Buenos Aires C1245AAM, Argentina.

Context: Patients with TSH-beta subunit defects and congenital hypothyroidism are missed by TSH-based neonatal screening.

Objective: Our objective was to report the molecular consequences of a novel splice-junction mutation and a novel missense mutation in the TSH-beta subunit gene found in two patients with congenital central hypothyroidism and conventional treatment-resistant anemia.

Results: Patient 1 had a homozygous G to A nucleotide change at the 5' donor splice site of exon/intron 2. This resulted in a silent change at codon 34 of the mature protein. In vitro splicing assays showed that the mutant minigene dramatically affected pre-mRNA processing, causing exon 2 to be completely skipped. The putative product from a new out-of-frame translational start point in exon 3 is expected to yield a nonsense 25-amino-acid peptide. In patient 2, sequence analysis revealed a compound heterozygosis for the already reported 313delT (C105Vfs114X) mutation and for a second novel mutation in exon 3, substituting G for A at cDNA nucleotide position 323, resulting in a C88Y change. This cysteine residue is conserved among all dimeric pituitary and placental glycoprotein hormone-beta subunits. Data from in silico analysis confirmed that the C88Y mutation would affect subunit conformation. Indeed, two different bioinformatics approaches, PolyPhen and SIFT analysis, predicted C88Y to be a damaging substitution.

Conclusions: In isolated TSH deficiency, the exact molecular diagnosis is mandatory for diagnosis of isolated pituitary deficiency, delineation of prognosis, and genetic counseling. Moreover, diagnosis of central hypothyroidism should be considered in the face of severe infant anemia of uncertain etiology.
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http://dx.doi.org/10.1210/jc.2010-0223DOI Listing
September 2010

Metformin, estrogen replacement therapy and gonadotropin inhibition fail to improve insulin sensitivity in a girl with aromatase deficiency.

Horm Res 2009 21;72(6):370-6. Epub 2009 Oct 21.

Endocrine Service, Hospital de Pediatría Garrahan, Buenos Aires, Argentina.

Background: 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.

Aims: To study insulin sensitivity, as well as the effects of estrogen, metformin and GnRHa treatment on glucose homeostasis, in an aromatase-deficient girl.

Methods: Clinical, metabolic and hormonal follow-up data, from 8 to 12 years of age, is presented.

Results: 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.

Conclusion: 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.
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http://dx.doi.org/10.1159/000249165DOI Listing
February 2010

Hydrocortisone treatment in girls with congenital adrenal hyperplasia inhibits serum dehydroepiandrosterone sulfate and affects the GH-IGF-I system.

J Pediatr Endocrinol Metab 2009 Mar;22(3):255-61

Hospital de Pediatría Garrahan, Endocrinology Service, Buenos Aires, Argentina.

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.
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http://dx.doi.org/10.1515/jpem.2009.22.3.255DOI Listing
March 2009

Adrenarche: postnatal adrenal zonation and hormonal and metabolic regulation.

Horm Res 2008 30;70(5):257-67. Epub 2008 Sep 30.

Servicio de Endocrinología, Hospital de Pediatría Garrahan, Buenos Aires, Argentina.

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.
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http://dx.doi.org/10.1159/000157871DOI Listing
January 2009

Expression of the IGF and the aromatase/estrogen receptor systems in human adrenal tissues from early infancy to late puberty: implications for the development of adrenarche.

Rev Endocr Metab Disord 2009 Mar;10(1):51-61

Endocrinology Department, Garrahan Pediatric Hospital, Buenos Aires, Argentina.

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.
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http://dx.doi.org/10.1007/s11154-008-9105-1DOI Listing
March 2009

Role of IGFs and insulin in the human testis during postnatal activation: differentiation of steroidogenic cells.

Pediatr Res 2008 Jun;63(6):662-6

Endocrine Service, Hospital de Pediatria Garrahan, Buenos Aires C1245 AAM, Argentina.

Immunoexpression of IGF-I, IGF-II, type 1 IGF receptor (IGFR), insulin receptor (IR), and GH receptor (GHR) was analyzed in human testis, in three age groups (Gr): Gr1 (neonates), Gr2 (postnatal testicular activation), and Gr3 (early prepuberty). In interstitial cells, low IGF-I and GHR, but moderate IR immunoexpression was observed in all Grs. However, high expression of IGF-II in Gr1, and moderate expression of IGFR in Gr1 and Gr2 were found. In Leydig cell (LC), high expression of IGF-II, moderate expression of IGFR and GHR, and undetectable IGF-I was found. Moreover, IR was highly expressed in Gr2. The effect of IGF-I on cell proliferation (PI) and apoptosis (AI), induction of cytochrome P450 side chain cleavage (cP450scc) immunoexpression, 3beta-hydroxysteroid dehydrogenase mRNA and testosterone (T) secretion was evaluated in human testis cell cultures. IGF-I increased P450scc immunoexpression, 3beta-hydroxysteroid dehydrogenase mRNA, T secretion, and PI, but decreased AI. We propose that IGF-II, mainly through IR, is involved in functional LC differentiation. In some interstitial cells, probably in LC precursors, IGF-II/IR could be involved, among other factors, in the stimulation of PI and/or inhibition of AI, and in LC differentiation.
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http://dx.doi.org/10.1203/PDR.0b013e31816c8ffcDOI Listing
June 2008

A new DAX-1 mutation in a family with a case of neonatal adrenal insufficiency and a sibling with adrenal hypoplasia and sudden death at 3 years of age.

J Pediatr Endocrinol Metab 2007 Sep;20(9):1039-43

Institute of Maternal and Child Research, Faculty of Medicine, University of Chile, Santiago.

Adrenal hypoplasia congenita (AHC) is a hereditary disorder that leads to adrenal insufficiency and hypogonadotropic hypogonadism (HHG) in childhood. The gene responsible for the X-linked form of AHC, DAX1 (dosage-sensitive sex-reversal, AHC, on the X-chromosome, gene 1)/NR0B1, encodes for a nuclear factor which lacks the characteristic zinc finger DNA-binding domain that is highly conserved in nuclear receptors. Deletions and point mutations in the DAX1 gene have been described in more than 70 AHC families. We present the clinical and genetic data of two brothers affected by AHC. We report a new DAX1 gene mutation in a family with two affected members: one with neonatal adrenal insufficiency, and a sibling with adrenal hypoplasia and sudden death at 3 years old. The NR0B1/DAX1 gene was amplified in three PCR fragments from the patient's and mother's gDNA extracted from peripheral lymphocytes. Sequencing revealed a novel single nucleotide deletion in codon 419 from exon 2 that resulted in a frameshift and a stop codon 17 nucleotides downstream (c.1256 delA). The mother was heterozygous for this mutation. In conclusion, a novel DAX-1 mutation was detected in two family members with different phenotype: one live infant with adrenal hypoplasia, his mother, and probably his dead brother.
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http://dx.doi.org/10.1515/jpem.2007.20.9.1039DOI Listing
September 2007

[Exon 5 alternative splicing of the cytochrome P450 aromatase could be a regulatory mechanism for estrogen production in humans].

Medicina (B Aires) 2007 ;67(4):369-73

Laboratorio de Investigación, Hospital Garrahan, Buenos Aires, Argentina.

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.
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September 2008