Clinical and Genetic Characterization of Familial Central Precocious Puberty.

CONTEXT: Central precocious puberty (CPP) can have a familial form in approximately one-quarter of the children. The recognition of this inherited condition increased after the identification of autosomal dominant CPP with paternal transmission caused by mutations in the MKRN3 and DLK1 genes. OBJECTIVE: We aimed to characterize the inheritance and estimate the prevalence of familial CPP in a large multiethnic cohort; to compare clinical and hormonal features, as well as treatment response to GnRH analogs (GnRHa), in children with distinct modes of transmission; and to investigate the genetic basis of familial CPP. METHODS: We retrospectively studied 586 children with a diagnosis of CPP. Patients with familial CPP (n = 276) were selected for clinical and genetic analysis. Data from previous studies were grouped, encompassing sequencing of MKRN3 and DLK1 genes in 204 patients. Large-scale parallel sequencing was performed in 48 individuals from 34 families. RESULTS: The prevalence of familial CPP was estimated at 22%, with a similar frequency of maternal and paternal transmission. Pedigree analyses of families with maternal transmission suggested an autosomal dominant inheritance. Clinical and hormonal features, as well as treatment response to GnRHa, were similar among patients with different forms of transmission of familial CPP. MKRN3 loss-of-function mutations were the most prevalent cause of familial CPP, followed by DLK1 loss-of-function mutations, affecting, respectively, 22% and 4% of the studied families; both affected exclusively families with paternal transmission. Rare variants of uncertain significance were identified in CPP families with maternal transmission. CONCLUSION: We demonstrated a similar prevalence of familial CPP with maternal and paternal transmission. MKRN3 and DLK1 loss-of-function mutations were the major causes of familial CPP with paternal transmission.

Insights from the genetic characterization of central precocious puberty associated with multiple anomalies.

STUDY QUESTION: Is there an (epi)genetic basis in patients with central precocious puberty (CPP) associated with multiple anomalies that unmasks underlying mechanisms or reveals novel genetic findings related to human pubertal control? SUMMARY ANSWER: In a group of 36 patients with CPP associated with multiple phenotypes, pathogenic or likely pathogenic (epi)genetic defects were identified in 12 (33%) patients, providing insights into the genetics of human pubertal control. WHAT IS KNOWN ALREADY: A few studies have described patients with CPP associated with multiple anomalies, but without making inferences on causalities of CPP. Genetic-molecular studies of syndromic cases may reveal disease genes or mechanisms, as the presentation of such patients likely indicates a genetic disorder. STUDY DESIGN, SIZE, DURATION: This translational study was based on a genetic-molecular analysis, including genome-wide high throughput methodologies, for searching structural or sequence variants implicated in CPP and DNA methylation analysis of candidate regions. PARTICIPANTS/MATERIALS, SETTING, METHODS: A cohort of 197 patients (188 girls) with CPP without structural brain lesions was submitted to a detailed clinical evaluation, allowing the selection of 36 unrelated patients (32 girls) with CPP associated with multiple anomalies. Pathogenic allelic variants of genes known to cause monogenic CPP (KISS1R, KISS1, MKRN3 and DLK1) had been excluded in the entire cohort (197 patients). All selected patients with CPP associated with multiple anomalies (n = 36) underwent methylation analysis of candidate regions and chromosomal microarray analysis. A subset (n = 9) underwent whole-exome sequencing, due to presenting familial CPP and/or severe congenital malformations and neurocognitive abnormalities. MAIN RESULTS AND THE ROLE OF CHANCE: Among the 36 selected patients with CPP, the more prevalent associated anomalies were metabolic, growth and neurocognitive conditions. In 12 (33%) of them, rare genetic abnormalities were identified: six patients presented genetic defects in loci known to be involved with CPP (14q32.2 and 7q11.23), whereas the other six presented defects in candidate genes or regions. In detail, three patients presented hypomethylation of DLK1/MEG3:IG-DMR (14q32.2 disruption or Temple syndrome), resulting from epimutation (n = 1) or maternal uniparental disomy of chromosome 14 (n = 2). Seven patients presented pathogenic copy number variants: three with de novo 7q11.23 deletions (Williams-Beuren syndrome), three with inherited Xp22.33 deletions, and one with de novo 1p31.3 duplication. Exome sequencing revealed potential pathogenic variants in two patients: a sporadic female case with frameshift variants in TNRC6B and AREL1 and a familial male case with a missense substitution in UGT2B4 and a frameshift deletion in MKKS. LIMITATIONS, REASONS FOR CAUTION: The selection of patients was based on a retrospective clinical characterization, lacking a longitudinal inclusion of consecutive patients. In addition, future studies are needed, showing the long-term (mainly reproductive) outcomes in the included patients, as most of them are not in adult life yet. WIDER IMPLICATIONS OF THE FINDINGS: The results highlighted the relevance of an integrative clinical-genetic approach in the elucidation of mechanisms and factors involved in pubertal control. Chromosome 14q32.2 disruption indicated the loss of imprinting of DLK1 as a probable mechanism of CPP. Two other chromosomal regions (7q11.23 and Xp22.33) represented new candidate loci potentially involved in this disorder of pubertal timing. STUDY FUNDING/COMPETING INTEREST(S): This work was supported by grant number 2018/03198-0 (to A.P.M.C.) and grant number 2013/08028-1 (to A.C.V.K) from the São Paulo Research Foundation (FAPESP), and grant number 403525/2016-0 (to A.C.L.) and grant number 302849/2015-7 (to A.C.L.) and grant number 141625/2016-3 (to A.C.V.K) from the National Council for Scientific and Technological Development (CNPq). The authors have nothing to disclose. TRIAL REGISTRATION NUMBER: N/A.

Genotype-Phenotype Correlations in Central Precocious Puberty Caused by MKRN3 Mutations.

CONTEXT: Loss-of-function mutations of makorin RING finger protein 3 (MKRN3) are the most common monogenic cause of familial central precocious puberty (CPP). OBJECTIVE: To describe the clinical and hormonal features of a large cohort of patients with CPP due to MKRN3 mutations and compare the characteristics of different types of genetic defects. METHODS: Multiethnic cohort of 716 patients with familial or idiopathic CPP screened for MKRN3 mutations using Sanger sequencing. A group of 156 Brazilian girls with idiopathic CPP (ICPP) was used as control group. RESULTS: Seventy-one patients (45 girls and 26 boys from 36 families) had 18 different loss-of-function MKRN3 mutations. Eight mutations were classified as severe (70% of patients). Among the 71 patients, first pubertal signs occurred at 6.2 ±â€…1.2 years in girls and 7.1 ±â€…1.5 years in boys. Girls with MKRN3 mutations had a shorter delay between puberty onset and first evaluation and higher follicle-stimulating hormone levels than ICPP. Patients with severe MKRN3 mutations had a greater bone age advancement than patients with missense mutations (2.3 ±â€…1.6 vs 1.6 ±â€…1.4 years, P = .048), and had higher basal luteinizing hormone levels (2.2 ±â€…1.8 vs 1.1 ±â€…1.1 UI/L, P = .018) at the time of presentation. Computational protein modeling revealed that 60% of the missense mutations were predicted to cause protein destabilization. CONCLUSION: Inherited premature activation of the reproductive axis caused by loss-of-function mutations of MKRN3 is clinically indistinct from ICPP. However, the type of genetic defect may affect bone age maturation and gonadotropin levels.

Pioneering studies on monogenic central precocious puberty.

Pubertal timing in humans is determined by complex interactions including hormonal, metabolic, environmental, ethnic, and genetic factors. Central precocious puberty (CPP) is defined as the premature reactivation of the hypothalamic-pituitary-gonadal axis, starting before the ages of 8 and 9 years in girls and boys, respectively; familial CPP is defined by the occurrence of CPP in two or more family members. Pioneering studies have evidenced the participation of genetic factors in pubertal timing, mainly identifying genetic causes of CPP in sporadic and familial cases. In this context, rare activating mutations were identified in genes of the kisspeptin excitatory pathway (KISS1R and KISS1 mutations). More recently, loss-of-function mutations in two imprinted genes (MKRN3 and DLK1) have been identified as important causes of familial CPP, describing novel players in the modulation of the hypothalamic-pituitary-gonadal axis in physiological and pathological conditions. MKRN3 mutations are the most common cause of familial CPP, and patients with MKRN3 mutations present clinical features indistinguishable from idiopathic CPP. Meanwhile, adult patients with DLK1 mutations present high frequency of metabolic alterations (overweight/obesity, early onset type 2 diabetes and hyperlipidemia), indicating that DLK1 may be a novel link between reproduction and metabolism. Arch Endocrinol Metab. 2019;63(4):438-44.

Pioneering studies on monogenic central precocious puberty

ABSTRACT Pubertal timing in humans is determined by complex interactions including hormonal, metabolic, environmental, ethnic, and genetic factors. Central precocious puberty (CPP) is defined as the premature reactivation of the hypothalamic-pituitary-gonadal axis, starting before the ages of 8 and 9 years in girls and boys, respectively; familial CPP is defined by the occurrence of CPP in two or more family members. Pioneering studies have evidenced the participation of genetic factors in pubertal timing, mainly identifying genetic causes of CPP in sporadic and familial cases. In this context, rare activating mutations were identified in genes of the kisspeptin excitatory pathway (KISS1R and KISS1 mutations). More recently, loss-of-function mutations in two imprinted genes (MKRN3 and DLK1) have been identified as important causes of familial CPP, describing novel players in the modulation of the hypothalamic-pituitary-gonadal axis in physiological and pathological conditions. MKRN3 mutations are the most common cause of familial CPP, and patients with MKRN3 mutations present clinical features indistinguishable from idiopathic CPP. Meanwhile, adult patients with DLK1 mutations present high frequency of metabolic alterations (overweight/obesity, early onset type 2 diabetes and hyperlipidemia), indicating that DLK1 may be a novel link between reproduction and metabolism. Arch Endocrinol Metab. 2019;63(4):438-44

Good response to long-term therapy with growth hormone in a patient with 9p trisomy syndrome: A case report and review of the literature.

The 9p trisomy syndrome is a rare condition, clinically characterized by a wide range of dysmorphic features, intellectual disability, and, in most patients, by short stature. Recombinant human growth hormone (rhGH) therapy is still controversial in syndromic disorders, the reason for which it is not currently indicated. Here we report a 7-year-old boy with 9p trisomy syndrome and marked short stature. Results of routine laboratory assessments were normal. IGF1 and IGFBP3 levels were both in the normal range (-1.6 and -0.7 SDS, respectively). GH peak in response to oral clonidine stimulation test was 3.5 µg/L, which is considered a normal response. Chromosomal analysis revealed the karyotype 47,XY, + del(9)(pter-q11:) dn. SNP array data indicated absence of mosaicism [arr 9p24.3-p13.1 (203,861-38,787,480) x3]. By the age of 8.3 years, the patient had persistent short stature (-2.9 SDS) with normal growth velocity (4.9 cm/y; -0.7 SDS), not showing spontaneous catch-up. After 5.6 years of rhGH therapy (50 µg/kg/d), height SDS improved from -2.9 to -1.0. This result suggests that rhGH therapy could be considered for patients with 9p trisomy syndrome who present with short stature. The degree of intellectual disability and the potential for social inclusion should be taken into account when recommending this treatment. Additional studies are needed to establish the benefits of height gain in these patients.

Variações no número de cópias cromossômicas submicroscópicas como causa de baixa estatura de início pré-natal / Submicroscopic chromosomal copy number variants as a cause of prenatal onset short stature

A pesquisa de variações no número de cópias (CNVs; copy number variants) cromossômicas tem revelado o importante papel destas alterações genômicas na diversidade populacional e na etiologia de doenças humanas. O modelo de associação de CNVs a doenças envolve deleções e/ou duplicações individualmente raras, mas com segmentos cromossômicos de tamanhos relevantes. Os pacientes com baixa estatura de início pré-natal constituem um grupo heterogêneo com quadros clínicos complexos frequentemente resultantes de alterações genéticas, que, desde o período intrauterino, perturbam os mecanismos e vias de desenvolvimento e crescimento fetais. Assim sendo, aventamos a hipótese de que CNVs raras possam estar entre as causas genéticas de baixa estatura de início prénatal. Para tanto, nosso estudo visou avaliar a presença de deleções ou duplicações submicroscópicas em um grupo selecionado de pacientes nascidos pequenos para idade gestacional (PIG) com baixa estatura persistente sem causa definida. Foram avaliados 51 pacientes nascidos PIG com baixa estatura persistente após o 4º ano de vida que apresentavam dismorfismos, atraso de desenvolvimento neuropsicomotor (DNPM) ou deficiência intelectual, porém sem caracterizar síndromes conhecidas e com cariótipo normal. Amostras de DNA dos pacientes foram submetidas à hibridização genômica comparativa por microarray (aCGH; array comparative genomic hybridization) baseada em oligonucleotídeos na plataforma 60K. Os achados foram comparados com CNVs descritas em bancos de dados de controles normais. Foram identificadas 18 CNVs, ausentes em controles saudáveis, em 17 dos 51 pacientes (33%). As alterações foram avaliadas para classificação de sua patogenicidade de acordo com os seguintes critérios: 1) padrão de herança e segregação familiar; 2) sobreposição a coordenadas genômicas de síndromes conhecidas; 3) sobreposição a CNVs patogênicas descritas em banco de dados; 4) e conteúdo gênico. Quatro CNVs, encontradas em 3 pacientes, foram...

Analysis of chromosomic copy number variants (CNVs) have demonstrated the important role of these genomic imbalances in population diversity and human disease. The model of CNV disease association involves deletions and/or duplications that are individually rare but encompass chromosomal segments of relevant size. Prenatal onset short stature patients constitute a complex group characterized by clinical heterogeneity. The causes of prenatal growth impairment frequently involve genetic changes that disturb the mechanisms and the pathways of fetal growth and development. Thus, we hipothesized that rare CNVs might contribute to the genetic etiology of prenatal onset short stature. In order to evaluate this assumption, our study analyzed the presence of submicroscopic deletions and/or duplications in a selected group of patients born small for gestational age with persistent short stature but without a recognized cause. A total of 51 patients with prenatal and postnatal growth retardation associated with dysmorphic features, developmental delay and/or intellectual disability, but without criteria for known syndromes, were selected. All patients had normal G-banded karyotyping. Array-based comparative genomic hybridization (aCGH) in a whole-genome 60K platform was performed using DNA obtained from all patients. Detected CNVs were compared with CNV data from healthy controls individuals, excluding common copy number polymorphisms. In 17 of the 51 patients screened (33%), 18 rare CNVs were identified. The pathogenicity of CNVs was assessed by considering the following criteria: inheritance and familial segregation; overlap with genomic coordinates for a known genomic imbalance syndrome; overlap with CNVs previously identified in other patients with prenatal onset short stature; and gene content. Four distinct CNVs, found in three patients, were classified as pathogenic: 1) del 22q11.21; 2) dup 10q26.2-26.3 and del 10q26.3; and 3) del 4q28.2-q31.21. Five CNVs, found...

Mutações no gene do receptor do fator de crescimento insulina-símile 1 (IGF1R) como causa de retardo do crescimento pré- e pós-natal / Mutations in insulin-like growth factor receptor 1 gene (IGF1R) resulting in intrauterine and postnatal growth retardation

Aproximadamente 10 por cento das crianças nascidas pequenas para a idade gestacional (PIGs) não apresentam recuperação espontânea do crescimento. As causas desse déficit de crescimento pré-natal e sua manutenção após o nascimento ainda não são completamente conhecidas na maioria dos casos. Nos últimos oito anos, diversas mutações inativadoras e deleções do gene IGF1R em heterozigose foram relatadas, indicando o papel de defeitos no eixo IGFs/IGF1R como causa do déficit de crescimento. Postula-se que pelo menos 2,5 por cento das crianças nascidas PIGs possam apresentar defeitos no gene IGF1R. O quadro clínico desses pacientes apresenta grande variabilidade quanto à gravidade do retardo de crescimento e aos parâmetros hormonais. Nos casos mais evidentes, os pacientes apresentam microcefalia, déficit cognitivo leve e valores elevados de IGF-1, associados à baixa estatura de início pré-natal. Esta revisão abordará os aspectos clínicos, moleculares e do tratamento da baixa estatura com hrGH de crianças com mutações no IGF1R.

Approximately 10 percent 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 percent 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.

[Mutations in insulin-like growth factor receptor 1 gene (IGF1R) resulting in intrauterine and postnatal growth retardation]. / Mutações no gene do receptor do fator de crescimento insulina-símile 1 (IGF1R) como causa de retardo do crescimento pré- e pós-natal.

Approximately 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.