ANDREA DE CASTRO LEAL
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article 6 Citação(ões) na Scopus Mutations in insulin-like growth factor receptor 1 gene (IGF1R) resulting in intrauterine and postnatal growth retardation(2011) LEAL, Andrea de Castro; CANTON, Ana Pinheiro Machado; MONTENEGRO, Luciana Ribeiro; COUTINHO, Debora Cabral; ARNHOLD, Ivo Jorge Prado; JORGE, Alexander Augusto de LimaApproximately 10% of children born small-for-gestational age (SGA) do not show spontaneous growth catch-up. The causes of this deficit in prenatal growth and its maintenance after birth are not completely known, in most cases. Over the past eight years, several heterozygous inactivating mutations and deletions in IGF1R gene have been reported, indicating the role of defects in the IGFs/IGF1R axis as a cause of growth deficit. It has been hypothesized that at least 2.5% of children born SGA may have IGF1R gene defects. The clinical presentation of these patients is highly variable in the severity of growth retardation and hormonal parameters. In the most evident cases, patients have microcephaly, mild cognitive impairment and high levels of IGF-1, associated with short stature of prenatal onset. This review will describe the clinical, molecular and treatment of short stature with hrGH of children with mutations in the IGF1R gene. Arq Bras Endocrinol Metab. 2011;55(8):541-9bookPart Deficiência do crescimento pré e pós-natal por mutação no gene IGF1R(2012) LEAL, Andréa de Castro; JORGE, Alexander Augusto de Lima- Post-receptor IGF1 insensitivity restricted to the MAPK pathway in a Silver-Russell syndrome patient with hypomethylation at the imprinting control region on chromosome 11(2012) MONTENEGRO, Luciana R.; LEAL, Andrea C.; COUTINHO, Debora C.; VALASSI, Helena P. L.; NISHI, Mirian Y.; PARNHOLD, Ivo J.; MENDONCA, Berenice B.; JORGE, Alexander A. L.Background: Hypomethylation of the paternal imprinting center region 1 (ICR1) is the most frequent molecular cause of Silver-Russell syndrome (SRS). Clinical evidence suggests that patients with this epimutation have mild IGF1 insensitivity. Objective: To assess in vitro IGF1 action in fibroblast culture from a patient with SRS and IGF1 insensitivity. Methods: Fibroblast cultures from one patient with SRS due to ICR1 demethylation and controls were established. The SRS patient has severe growth failure, elevated IGF1 level, and poor growth rate during human recombinant GH treatment. IGF1 action was assessed by cell proliferation, AKT, and p42/44-MAPK phosphorylation. Gene expression was determined by real-time PCR. Results: Despite normal IGF1R sequence and expression, fibroblast proliferation induced by IGF1 was 50% lower in SRS fibroblasts in comparison with controls. IGF1 and insulin promoted a p42/44-MAPK activation in SRS fibroblasts 40 and 36%, respectively, lower than that in control fibroblasts. On the other hand, p42/44-MAPK activation induced by EGF stimulation was only slightly reduced (75% in SRS fibroblasts in comparison with control), suggesting a general impairment in MAPK pathway with a greater impairment of the stimulation induced by insulin and IGF1 than by EGF. A PCR array analysis disclosed a defect in MAPK pathway characterized by an increase in DUSP4 and MEF2C gene expressions in patient fibroblasts. Conclusion: A post-receptor IGF1 insensitivity was characterized in one patient with SRS and ICR1 hypomethylation. Although based on one unique severely affected patient, these results raise an intriguing mechanism to explain the postnatal growth impairment observed in SRS patients that needs confirmation in larger cohorts.
- Analysis of the insulin-like growth factor 1 receptor gene in children born small for gestational age: in vitro characterization of a novel mutation (p.Arg511Trp)(2013) LEAL, Andrea C.; MONTENEGRO, Luciana R.; SAITO, Renata F.; RIBEIRO, Tamaya C.; COUTINHO, Debora C.; MENDONCA, Berenice B.; ARNHOLD, Ivo J. P.; JORGE, Alexander A. L.Background Insulin-like growth factor 1 insensitivity caused by IGF1R mutations has been previously identified as one of the causes of growth impairment in children born small for gestational age (SGA). Objective To analyse the IGF1R in children born SGA. Subjects From an initial cohort of 54 sequential children born SGA, without catch-up growth, 25 children were selected for this IGF1R study due to the presence of serum IGF-1 values above the mean for their age and sex. Methods The proximal IGF1R promoter region, the entire coding region and the exonintron boundaries were directly sequenced, and multiplex ligation-dependent probe amplification analysis was performed. Fibroblast cultures were developed from one patient with a mutation for the in vitro characterization of IGF-1 insensitivity. Results The copy number variation analysis did not identify deletions involving the IGF1R gene. We identified two children carrying heterozygous nucleotide substitutions in IGF1R: c.16G>A/p.Gly6Arg and c.1531C>T/p.Arg511Trp. The first variant (p.Gly6Arg) was identified in control subjects (0 center dot 3%) and in a relative with normal growth; thus, it was considered to be a rare benign allelic variation. The second variant (p.Arg511Trp) was not found in 306 alleles from control subjects, and it segregated with the growth impairment phenotype in the patient's family. Fibroblasts obtained from this patient had a significantly reduced proliferative response and AKT phosphorylation after IGF-1 stimulation compared with control fibroblasts. Conclusion The identification of an inactivating IGF1R mutation in the present cohort should encourage further studies of larger series to establish the precise frequency of this molecular defect in children with growth impairment of a prenatal onset.