Copy number variants in patients with short stature

Height is a highly heritable and classic polygenic trait. Recent genome-wide association studies (GWAS) have revealed that at least 180 genetic variants influence adult height. However, these variants explain only about 10% of the phenotypic variation in height. Genetic analysis of short individuals can lead to the discovery of novel rare gene defects with a large effect on growth. In an effort to identify novel genes associated with short stature, genome-wide analysis for copy number variants (CNVs), using single-nucleotide polymorphism arrays, in 162 patients (149 families) with short stature was performed. Segregation analysis was performed if possible, and genes in CNVs were compared with information from GWAS, gene expression in rodents'' growth plates and published information. CNVs were detected in 40 families. In six families, a known cause of short stature was found (SHOX deletion or duplication, IGF1R deletion), in two combined with a de novo potentially pathogenic CNV. Thirty-three families had one or more potentially pathogenic CNVs (n=40). In 24 of these families, segregation analysis could be performed, identifying three de novo CNVs and nine CNVs segregating with short stature. Four were located near loci associated with height in GWAS (ADAMTS17, TULP4, PRKG2/BMP3 and PAPPA). Besides six CNVs known to be causative for short stature, 40 CNVs with possible pathogenicity were identified. Segregation studies and bioinformatics analysis suggested various potential candidate genes.     

Cow's milk allergic children can present sensitisation to probiotics

Aim: To evaluate sensitivity to different probiotics in children with cow's milk allergy.
Methods: Eighty-five patients (age range: 4 months –12 years) presenting atopic dermatitis (AD) were enrolled. Skin prick test (SPT) responses to three different probiotics preparations (Fiorilac®, Dicoflor® and Reuterin®) were evaluated in addition to relevant food allergens.
Results: Thirty-nine patients out of 85 (45.8%) had a positive skin response to prick test for cow's milk (3 with reaction <3 mm). Of the thirty-six patients with a cow's milk weal reaction >3 mm, twenty-eight (77.8%) had a skin response to Fiorilac®, four patients (11%) to Dicoflor® and four (11%) to Reuterin®. The proportion of SPT reaction to all the investigated probiotics preparations was significantly lower than cow's milk (r = 9.406; p = 0.002). A significantly higher sensitization was observed for Fiorilac® versus Dicoflor® (r = 30.916; p < 0.001) and versus Reuterin® (r = 34.133; p < 0.001).
Conclusion: Probiotic use in patients with cow's milk allergy has to be limited to products that do not contain milk. This should be clearly reported in the label. In selected patients, it is advisable to perform a screening SPT with the product to evaluate its potential contamination with milk.     

Beta-defensin genomic copy number is not a modifier locus for cystic fibrosis

Human beta-defensin 2 (DEFB4, also known as DEFB2 or hBD-2) is a salt-sensitive antimicrobial protein that is expressed in lung epithelia. Previous work has shown that it is encoded in a cluster of beta-defensin genes at 8p23.1, which varies in copy number between 2 and 12 in different individuals. We determined the copy number of this locus in 355 patients with cystic fibrosis (CF), and tested for correlation between beta-defensin cluster genomic copy number and lung disease associated with CF. No significant association was found.     

Exaled nitric oxide and air trapping correlation in asthmatic children

Exhaled nitric oxide (eNO) levels have been shown to correlate with atopy and with airway hyperresponsiveness but not with standard spirometry. The aim of our study was to evaluate the correlation between eNo levels and functional residual capacity (FRC), residual volume (RV), RV to total lung capacity (TLC) ratio, and pulmonary resistances in asthmatic children ages 6-13 years. Forty-nine patients (35 males) were enrolled in the study. Nineteen of them were not receiving inhaled corticosteroids. The eNO levels were measured by chemiluminescence's analyzer and lung function study were performed by body box plethysmography. As expected, there was no correlation between eNO levels and forced vital capacity (FVC); forced expiratory volume in the first second (FEV1); mid respiratory flow between 25 and 75% of the vital capacity (MEF(25 -75)), FEV1/FVC, and pulmonary resistances. Instead a correlation was found between eNO level and RV both considering all the study population together (r = 0.51, P = 0.001) and separately the asthmatic children not receiving ICS (r = 0.6, P = 0.003). In the patients receiving ICS the correlation was still present (r = 0.43, P = 0.01). The correlation between eNo levels and RV may reflect the effect of airway inflammation on NO production and diffusion as well as peripheral airway trapping and consequent RV.     

Identification of MEN1 gene mutations in sporadic carcinoid tumors of the lung

Lung carcinoids occur sporadically and rarely in association with multiple endocrine neoplasia type 1 (MEN1). There are no well defined genetic abnormalities known to occur in these tumors. We studied 11 sporadic lung carcinoids for loss of heterozygosity (LOH) at the locus of the MEN1 gene on chromosome 11q13, and for mutations of the MEN1 gene using dideoxy fingerprinting. Additionally, a lung carcinoid from a MEN1 patient was studied. In four of 11 (36%) sporadic tumors, both copies of the MEN1 gene were inactivated. All four tumors showed the presence of a MEN1 gene mutation and loss of the other allele. Observed mutations included a 1 bp insertion, a 1 bp deletion, a 13 bp deletion and a single nucleotide substitution affecting a donor splice site. Each mutation predicts truncation or potentially complete loss of menin. The remaining seven tumors showed neither the presence of a MEN1 gene mutation nor 11q13 LOH. The tumor from the MEN1 patient showed LOH at chromosome 11q13 and a complex germline MEN1 gene mutation. The data implicate the MEN1 gene in the pathogenesis of sporadic lung carcinoids, representing the first defined genetic alteration in these tumors.      

Morphological analysis of degeneration and regeneration of syncytiotrophoblast in first trimester placental villi during organ culture

We have recently shown using dansyl-L-lysine exclusion studies that the release of human chorionic gonadotrophin (HCG) in conjunction with L- lactate dehydrogenase (LDH) from first trimester villi during organ culture is symptomatic of syncytiotrophoblast degeneration. The purpose of this study was to examine chorionic villi at the ultrastructural level in order to determine events occurring during organ culture. The tissue was sampled after 0, 24, 48 and 120 h in culture and processed for electron microscopy. In addition to confirming the previously recorded syncytial degeneration, the electron micrographs showed clearly the generation of a new syncytiotrophoblast layer. The new layer, derived from differentiating cytotrophoblast cells, was largely formed by 48 h and was maintained for at least 120 h in culture. This study demonstrates a model which provides an opportunity to study the differentiation of cytotrophoblast cells whilst they retain their anatomical relationships within the villous structure.      

Improved bronchodilator effect of deep inhalation after allergen avoidance in asthmatic children

BACKGROUND: In healthy adults and children, deep inhalation (DI) is able to reverse induced bronchoconstriction. This ability is impaired in asthma, but the reasons are still to be elucidated. OBJECTIVES: This study investigated whether the bronchodilator effect of DI during methacholine-induced bronchoconstriction can be improved by allergen avoidance in asthmatic children, and its relationship with airway inflammation. METHODS: The effect of DI on methacholine-induced bronchoconstriction was studied at the beginning and the end of a 3-month allergen avoidance period at high altitude in 14 allergic asthmatic children who had severe asthma attacks. Changes in airway caliber were inferred from the respiratory resistance (Rrs) measured by a forced oscillation technique. Results were related to the percentage of eosinophils in induced sputum and compared with those obtained in 9 age-matched nonasthmatic children. RESULTS: In asthmatic subjects, DI had no significant effect on methacholine-induced increase in Rrs before (P=.62) but significantly reversed it after (P <.01) allergen avoidance. However, the ability of DI to reverse a methacholine-induced increase in Rrs tended to remain less in asthmatic than nonasthmatic children even after allergen avoidance (P=.05). In the asthmatic children, the percentage of eosinophils in induced sputum was decreased at the end of the allergen avoidance period (P <.001), without any significant correlation between sputum eosinophils and airway responsiveness to methacholine or effect of DI. CONCLUSION: A short period of allergen avoidance may improve the ability of DI to reverse induced bronchoconstriction in some asthmatic children. This effect is associated, yet not correlated, with a reduction in airway inflammation.     

Missense FGFR3 mutations create cysteine residues in thanatophoric dwarfism type I (TD1)

Thanatophoric dwarfism (TD) is a sporadic lethal skeletal dysplasia with micromelic shortening of the limbs, macrocephaly, platyspondyly and reduced thoracic cavity. In the most common subtype (TD1), femurs are curved, while in TD2, straight femurs are associated with cloverleaf skull. Mutations in the fibroblast growth factor receptor 3 (FGFR3) gene were identified in both subtypes. While TD2 was accounted for by a single recurrent mutation in the tyrosine kinase 2 domain, TD1 resulted from either stop codon mutations or missense mutations in the extracellular domain of the gene. Here, we report the identification of FGFR3 mutations in 25/26 TD cases. Two novel missense mutations (Y373C and G370C) were detected in 8/26 and 1/26 TD1 cases respectively. Both mutations created cysteine residues in the juxta extramembrane domain of the receptor. Sixteen cases carried the previously reported R248C (9/26 cases), S249C (2/26 cases) or stop codon FGFR3 mutations (5/26 cases). Our results suggest that TD1 is a genetically homogeneous condition and give additional support to the view that newly created cysteine residues in the extracellular domain of the protein play a key role in the severity of the disease.