Mariana F. A. Funari

Heterozygous Mutations in Natriuretic Peptide Receptor-B (NPR2) Gene as a Cause of Short Stature in Patients Initially Classified as Idiopathic Short Stature

CONTEXT Based on the stature observed in relatives of patients with acromesomelic dysplasia, type Maroteaux, homozygous for mutations in natriuretic peptide receptor B gene (NPR2), it has been suggested that heterozygous mutations in this gene could be responsible for the growth impairment observed in some children with idiopathic short stature (ISS). OBJECTIVE The objective of the study was to investigate the presence of NPR2 mutations in a group of patients with ISS. PATIENTS AND METHODS The NPR2 coding region was directly sequenced in 47 independent patients with ISS. The functional consequences of NPR2 nonsynonymous variations were established using in vitro cell-based assays. RESULTS Three novel heterozygous NPR2 mutations were identified: c.226T>C (p.Ser76Pro), c.788G>C (p.Arg263Pro), and c.2455C>T (p.Arg819Cys). These allelic variants were not found in our controls or in the 1000 Genomes database. In silico analysis suggested that the three missense mutations are probably damaging. All of them were selected for in vitro functional evaluation. Cells transfected with the three mutants failed to produce cyclic GMP after treatment with C-type natriuretic peptide. Cells cotransfected with mutant and wild-type-NPR-B (1:1) showed a significant decrease in cGMP levels after C-type natriuretic peptide stimulation in comparison with cells cotrasnfected with empty vector and wild type, suggesting a dominant-negative effect. These three mutations segregated with short stature phenotype in an autosomal dominant pattern (height SD score ranged from -4.5 to -1.7). One of these patients and two relatives have disproportionate short stature, whereas in another patient a nonspecific skeletal abnormality was observed. All three of these patients were treated with recombinant human GH (33-50 μg/kg · d) without significant height SD score change during therapy. CONCLUSIONS We identified heterozygous NPR2 mutations in 6% of patients initially classified as ISS. Affected patients have mild and variable degrees of short stature without a distinct phenotype. Heterozygous mutations in NPR2 could be an important cause of nonsyndromic familial short stature.

Effectiveness of the Combined Recombinant Human Growth Hormone and Gonadotropin-Releasing Hormone Analog Therapy in Pubertal Patients with Short Stature due to SHOX Deficiency

CONTEXT Isolated heterozygous SHOX defects are the most frequent monogenic cause of short stature, and combined therapy with recombinant human GH (rhGH) and GnRH analog (GnRHa) in pubertal patients has been suggested, but there are no data on final height. OBJECTIVE The aim of the study was to analyze adult height after rhGH and GnRHa therapy in patients with SHOX haploinsufficiency. PATIENTS Ten peripubertal patients with isolated SHOX defects participated in the study. INTERVENTION Five patients were followed without treatment, and five were treated with rhGH (50 mug/kg/d) and depot leuprolide acetate (3.75 mg/month). MAIN OUTCOME MEASURES Adult height sd score (SDS) was measured. RESULTS All patients followed without treatment had marked downward growth shift during puberty (height SDS, -1.2 +/- 0.7 at 11.4 +/- 1.4 yr; adult height SDS, -2.5 +/- 0.5). Conversely, four of five patients treated with rhGH for 2 to 4.9 yr associated to GnRHa for 1.4 to 5.8 yr improved their height SDS from -2.3 +/- 1.3 at 11.8 +/- 2.1 yr to a final height SDS of -1.7 +/- 1.6. The difference between the mean height SDS at the first evaluation and final height SDS was statistically significant in nontreated vs. treated patients (mean height SDS change, -1.2 +/- 0.4 vs. 0.6 +/- 0.4, respectively; P <0.001). CONCLUSION A gain in adult height of patients with isolated SHOX defects treated with combined rhGH and GnRHa therapy was demonstrated for the first time, supporting this treatment for children with SHOX defects who have just started puberty to avoid the loss of growth potential observed in these patients during puberty.

The sitting height/height ratio for age in healthy and short individuals and its potential role in selecting short children for SHOX analysis.

Aims: To determine the presence of abnormal body proportion, assessed by sitting height/height ratio for age and sex (SH/H SDS) in healthy and short individuals, and to estimate its role in selecting short children for SHOX analysis. Methods: Height, sitting height and weight were evaluated in 1,771 healthy children, 128 children with idiopathic short stature (ISS), 58 individuals with SHOX defects (SHOX-D) and 193 females with Turner syndrome (TS). Results: The frequency of abnormal body proportion, defined as SH/H SDS >2, in ISS children was 16.4% (95% CI 10-22%), which was higher than in controls (1.4%, 95% CI 0.8-1.9%, p < 0.001). The SHOX gene was evaluated in all disproportionate ISS children and defects in this gene were observed in 19%. Among patients with SHOX-D, 88% of children (95% CI 75-100%) and 96% of adults had body disproportion. In contrast, SH/H SDS >2 were less common in children (48%, 95% CI 37-59%) and in adults (28%, 95% CI 20-36%) with TS. Conclusion: Abnormal body proportions were observed in almost all individuals with SHOX-D, 50% of females with TS and 16% of children considered ISS. Defects in SHOX gene were identified in 19% of ISS children with SH/H SDS >2, suggesting that SH/H SDS is a useful tool to select children for undergoing SHOX molecular studies.

Clinical characterization of patients with autosomal dominant short stature due to aggrecan mutations

Context: Heterozygous mutations in the aggrecan gene (ACAN) cause autosomal dominant short stature with accelerated skeletal maturation. Objective: We sought to characterize the phenotypic spectrum and response to growth-promoting therapies. Patients and Methods: One hundred three individuals (57 females, 46 males) from 20 families with autosomal dominant short stature and heterozygous ACAN mutations were identified and confirmed using whole-exome sequencing, targeted next-generation sequencing, and/or Sanger sequencing. Clinical information was collected from the medical records. Results: Identified ACAN variants showed perfect cosegregation with phenotype. Adult individuals had mildly disproportionate short stature [median height, −2.8 standard deviation score (SDS); range, −5.9 to −0.9] and a history of early growth cessation. The condition was frequently associated with early-onset osteoarthritis (12 families) and intervertebral disc disease (9 families). No apparent genotype–phenotype correlation was found between the type of ACAN mutation and the presence of joint complaints. Childhood height was less affected (median height, −2.0 SDS; range, −4.2 to −0.6). Most children with ACAN mutations had advanced bone age (bone age − chronologic age; median, +1.3 years; range, +0.0 to +3.7 years). Nineteen individuals had received growth hormone therapy with some evidence of increased growth velocity. Conclusions: Heterozygous ACAN mutations result in a phenotypic spectrum ranging from mild and proportionate short stature to a mild skeletal dysplasia with disproportionate short stature and brachydactyly. Many affected individuals developed early-onset osteoarthritis and degenerative disc disease, suggesting dysfunction of the articular cartilage and intervertebral disc cartilage. Additional studies are needed to determine the optimal treatment strategy for these patients.

Cryptic intragenic deletion of the SHOX gene in a family with Léri-Weill dyschondrosteosis detected by Multiplex Ligation-Dependent Probe Amplification (MLPA)

LWD is associated to SHOX haploinsufficiency, in most cases, due to gene deletion. Generally FISH and microsatellite analysis are used to identify SHOX deletion. MLPA is a new method of detecting gene copy variation, allowing simultaneous analysis of several regions. Here we describe the presence of a SHOX intragenic deletion in a family with LWD, analyzed through different methodologies. Genomic DNA of 11 subjects from one family were studied by microsatellite analysis, direct sequencing and MLPA. FISH was performed in two affected individuals. Microsatellite analysis showed that all affected members shared the same haplotype suggesting the involvement of SHOX. MLPA detected an intragenic deletion involving exons IV-VIa, which was not detected by FISH and microsatellite analysis. In conclusion, the MLPA technique was proved to be the best solution on detecting this small deletion, it has the advantage of being less laborious also allowing the analysis of several regions simultaneously.

Baixa estatura por haploinsuficiência do gene SHOX: do diagnóstico ao tratamento

SUMMARY Short stature caused by SHOX gene haploinsufficiency: from diagnosis to treatment. studies involving patients with short stature and partial deletion of sex chro-mosomes identified shoX gene in the pseudoautosomal region of the X and Y chromosomes. shoX haploinsufficiency is an important cause of short stature in a diversity of clinical conditions. it explains 2/3 of short stature observed in turner syndrome (ts) patients. Heterozygous mutations in sHoX are observed in 77% of patients with leri-Weill dyschondrosteosis, a common dominant in-herited skeletal dysplasia and in 3% of children with idiopathic short stature, indicating that shoX defects are the most frequent monogenetic cause of short stature. the sitting height/height ratio (sH/H) standard deviation score is a sim-ple way to assess body proportions and together with a careful exam of other family members, effectively selected a group of patients that presented a high frequency of shoX mutations. growth hormone treatment of short stature due to ts is well established and considering the common etiology of short stature in patients with isolated defects of

Two Patients with Severe Short Stature due to a FBN1 Mutation (p.Ala1728Val) with a Mild Form of Acromicric Dysplasia

Background: Acromicric dysplasia (AD) and geleophysic dysplasia 2 (GD2) belong to the category of acromelic dysplasia syndromes, consisting of severe short stature, short hands and feet and skin thickening. Both can result from missense mutations in the transforming growth factor beta 5 domain of the fibrillin-1 gene (FBN1). Methods: Two patients (P1 age 10, and P2 age 7) from unrelated families presented to their endocrinologist with severe short stature (approx. -4 SDS). They were otherwise asymptomatic and only had mild facial dysmorphisms. Extensive endocrine work-up did not reveal an underlying etiology. Exome sequencing was performed in each family. Results: Exome sequencing identified the presence of the same heterozygous missense variant c.C5183T (p.Ala1728Val) in the FBN1 gene in both P1 and P2. This variant was previously reported in a patient with GD2 and associated cardiac valvulopathy and hepatomegaly. Detailed clinical re-examination, cardiac and skeletal imaging did not reveal any abnormalities in P1 or P2 other than mild hip dysplasia. Conclusion: This report broadens the phenotypic spectrum of growth disorders associated with FBN1 mutations. Identical mutations give rise to a wide phenotypic spectrum, ranging from isolated short stature to a more classic picture of GD2 with cardiac involvement, distinct facial dysmorphisms and various skeletal anomalies.

A Novel Homozygous Missense FSHR Variant Associated with Hypergonadotropic Hypogonadism in Two Siblings from a Brazilian Family

Hypergonadotropic hypogonadism (HH) is defined by increased gonadotropin levels in men and women. Primary ovarian failure (POF) is a form of female infertility characterized by amenorrhea, hypoestrogenism, and elevated gonadotropin levels in women under the age of 40 years. Although several genes have been associated with POF, its causative genes remain to be identified. Here, we used whole-exome sequencing (WES) to study a consanguineous family with a 46,XX girl and a 46,XY man affected by HH. All exons of both siblings and their parents were captured and massively sequenced by WES, and the candidate variant was confirmed by Sanger sequencing. A novel c.1298C>A;p.Ala433Asp missense variant of the follicle-stimulating hormone receptor (FSHR) gene was found in both affected siblings in a homozygous state and in their parents in a heterozygous state. This FSHR variant is not present in available databases (1000 Genomes and NHLBI/EVS) and Brazilian exome controls. Moreover, it is highly conserved and predicted as deleterious in all prediction sites analyzed. In conclusion, the novel homozygous FSHR variant observed in 2 siblings with HH can expand the spectrum of FSHR mutations in humans.

Mutations in C-natriuretic peptide ( NPPC ): a novel cause of autosomal dominant short stature

PurposeC-type natriuretic peptide (CNP) and its principal receptor, natriuretic peptide receptor B (NPR-B), have been shown to be important in skeletal development. CNP and NPR-B are encoded by natriuretic peptide precursor-C (NPPC) and natriuretic peptide receptor 2 (NPR2) genes, respectively. While NPR2 mutations have been described in patients with skeletal dysplasias and idiopathic short stature (ISS), and several Npr2 and Nppc skeletal dysplasia mouse models exist, no mutations in NPPC have been described in patients to date.MethodsNPPC was screened in 668 patients (357 with disproportionate short stature and 311 with autosomal dominant ISS) and 29 additional ISS families in an ongoing whole-exome sequencing study.ResultsTwo heterozygous NPPC mutations, located in the highly conserved CNP ring, were identified. Both showed significant reductions in cyclic guanosine monophosphate synthesis, confirming their pathogenicity. Interestingly, one has been previously linked to skeletal abnormalities in the spontaneous Nppc mouse long-bone abnormality (lbab) mutant.ConclusionsOur results demonstrate, for the first time, that NPPC mutations cause autosomal dominant short stature in humans. The NPPC mutations cosegregated with a short stature and small hands phenotype. A CNP analog, which is currently in clinical trials for the treatment of achondroplasia, seems a promising therapeutic approach, since it directly replaces the defective protein.

IHH Gene Mutations Causing Short Stature With Nonspecific Skeletal Abnormalities and Response to Growth Hormone Therapy

Context Genetic evaluation has been recognized as an important tool to elucidate the causes of growth disorders. Objective To investigate the cause of short stature and to determine the phenotype of patients with IHH mutations, including the response to recombinant human growth hormone (rhGH) therapy. Patients and Methods We studied 17 families with autosomal-dominant short stature by using whole exome sequencing and screened IHH defects in 290 patients with growth disorders. Molecular analyses were performed to evaluate the potential impact of N-terminal IHH variants. Results We identified 10 pathogenic or possibly pathogenic variants in IHH, an important regulator of endochondral ossification. Molecular analyses revealed a smaller potential energy of mutated IHH molecules. The allele frequency of rare, predicted to be deleterious IHH variants found in short-stature samples (1.6%) was higher than that observed in two control cohorts (0.017% and 0.08%; P < 0.001). Identified IHH variants segregate with short stature in a dominant inheritance pattern. Affected individuals typically manifest mild disproportional short stature with a frequent finding of shortening of the middle phalanx of the fifth finger. None of them have classic features of brachydactyly type A1, which was previously associated with IHH mutations. Five patients heterozygous for IHH variants had a good response to rhGH therapy. The mean change in height standard deviation score in 1 year was 0.6. Conclusion Our study demonstrated the association of pathogenic variants in IHH with short stature with nonspecific skeletal abnormalities and established a frequent cause of growth disorder, with a preliminary good response to rhGH.