ABSTRACT
BACKGROUND: The type 1 insulin-like growth factor receptor (IGF1R) is a keystone of fetal growth regulation by mediating the effects of IGF-I and IGF-II. Recently, a cohort of patients carrying an IGF1R defect was described, from which a clinical score was established for diagnosis. We assessed this score in a large cohort of patients with identified IGF1R defects, as no external validation was available. Furthermore, we aimed to develop a functional test to allow the classification of variants of unknown significance (VUS) in vitro. METHODS: DNA was tested for either deletions or single nucleotide variant (SNV) and the phosphorylation of downstream pathways studied after stimulation with IGF-I by western blot analysis of fibroblast of nine patients. RESULTS: We detected 21 IGF1R defects in 35 patients, including 8 deletions and 10 heterozygous, 1 homozygous and 1 compound-heterozygous SNVs. The main clinical characteristics of these patients were being born small for gestational age (90.9%), short stature (88.2%) and microcephaly (74.1%). Feeding difficulties and varying degrees of developmental delay were highly prevalent (54.5%). There were no differences in phenotypes between patients with deletions and SNVs of IGF1R. Functional studies showed that the SNVs tested were associated with decreased AKT phosphorylation. CONCLUSION: We report eight new pathogenic variants of IGF1R and an original case with a homozygous SNV. We found the recently proposed clinical score to be accurate for the diagnosis of IGF1R defects with a sensitivity of 95.2%. We developed an efficient functional test to assess the pathogenicity of SNVs, which is useful, especially for VUS.
Subject(s)
Abnormalities, Multiple/genetics , Fetal Development/genetics , Fetal Growth Retardation/genetics , Growth Disorders/genetics , Receptor, IGF Type 1/genetics , Abnormalities, Multiple/epidemiology , Abnormalities, Multiple/physiopathology , Adolescent , Child , Dwarfism/genetics , Dwarfism/physiopathology , Female , Fetal Growth Retardation/epidemiology , Fetal Growth Retardation/physiopathology , Growth Disorders/epidemiology , Growth Disorders/physiopathology , Heterozygote , Homozygote , Humans , Infant, Small for Gestational Age/growth & development , Insulin-Like Growth Factor I/genetics , Insulin-Like Growth Factor II/genetics , Male , Microcephaly/genetics , Microcephaly/physiopathology , Mutation, Missense/genetics , Pedigree , Polymorphism, Single Nucleotide/genetics , Receptors, Somatomedin/geneticsABSTRACT
CONTEXT AND OBJECTIVE: Idiopathic central precocious puberty (iCPP) is defined as early activation of the hypothalamic-pituitary-gonadal axis in the absence of identifiable central lesions. Mutations of the makorin RING finger 3 (MKRN3) gene are associated with iCPP. We aimed to assess the frequency of MKRN3 mutations in iCPP and to compare the phenotypes of patients with and without MKRN3 mutations. DESIGN: An observational study was carried out on patients recruited at pediatric hospitals in France and Italy. Forty-six index CPP cases were screened for mutations in the MKRN3 coding sequence: 28 index cases of familial cases and 18 cases did not report any familial history of CPP. The endocrine phenotype was compared between MKRN3 mutated and non-mutated patients. RESULTS: MKRN3 mutations were identified in one sporadic and 13 familial cases. We identified five new heterozygous missense mutations predicted to be deleterious for protein function and two frameshift mutations, one new and the other recurrent, predicted to result in truncated proteins. Age at puberty onset varied very little among patients with MKRN3 mutations and puberty occurred earlier in these patients than in those without MKRN3 mutations (6.0 years (5.4-6.0) vs 7.0 years (6.0-7.0), P=0.01). CONCLUSIONS: MKRN3 mutations are common in familial iCPP. MKRN3 is one of the gatekeepers of the postnatal activation of the gonadotropic axis.
Subject(s)
Puberty, Precocious/genetics , Ribonucleoproteins/genetics , Child , Child, Preschool , Fathers , Female , Frameshift Mutation , France , Heterozygote , Humans , Italy , Male , Mothers , Mutation , Mutation, Missense , Pedigree , Phenotype , Puberty , Ubiquitin-Protein LigasesABSTRACT
UNLABELLED: BACKGROUNDAIM: In growth disorders, ensuring long-term growth hormone therapy (GHT) remains a challenge that might compromise the clinical outcome. Consequently, strategies aiming at alleviating the burden of daily injection might improve the treatment benefit. The study reported here was performed to assess the ease of use of Norditropin NordiFlex(®) (Novo Nordisk, Princeton, NJ, USA) compared with that of the devices previously used in children treated with GHT with recombinant somatropin. METHODS: This Phase IV prospective, multicenter, open-label study was conducted in France. All patients received Norditropin NordiFlex for 6 weeks. Oral questionnaires were administered by the physician to the patients and/or the parents at inclusion and at the final visit. RESULTS: This study included 103 patients aged between 6 and 17 years. The patients assessed Norditropin NordiFlex as significantly easier to use than their previous device (median value = 7.5, P < 0.001). Almost three-quarters of patients (64.4%) preferred Norditropin NordiFlex to their previous device. Among physicians and nurses, 73% assessed Norditropin NordiFlex training as "very easy" and 26% as "easy." Norditropin NordiFlex improved patient autonomy, with 41% of patients able to self-inject the treatment. CONCLUSION: This study has shown that Norditropin NordiFlex is reliable, safe, and easy to use and most study patients preferred it to their previous device. These characteristics may improve the adherence to GHT.
