IGF1 and PPARG polymorphisms are associated with reduced estimated glomerular filtration rate in a cohort of children and adolescents with type 1 diabetes.

INTRODUCTION: Several genetic loci have been associated with diabetic nephropathy; however, the underlying genetic mechanisms are still poorly understood, with no robust candidate genes identified yet. AIM: We aimed to determine whether two polymorphisms, previously associated with renal decline, influence kidney impairment evaluating their association with markers of renal function in a pediatric population with type 1 diabetes (T1D). MATERIAL AND METHODS: Renal function was evaluated by glomerular filtration rate (eGFR) and albumin-to-creatinine ratio (ACR) in a cohort of pediatric subjects with T1D (n = 278). Risk factors for diabetes complications (diabetes duration, blood pressure, HbA1c) were assessed. The IGF1 rs35767 and PPARG rs1801282 SNPs were genotyped by TaqMan RT-PCR system. An additive genetic interaction was calculated. Association analysis between markers of renal function and both SNPs or their additive interaction were performed. RESULTS: Both SNPs showed a significant association with eGFR: the A allele of rs35767 or the C allele of rs1801282 were associated to reduced eGFR compared to G alleles. Multivariate regression analysis adjusted for age, sex, z-BMI, T1D duration, blood pressure and Hba1c values showed that the additive genetic interaction was independently associated with lower eGFR (ß = -3.59 [-6.52 to -0.66], p = 0.017). No associations were detected between SNPs, their additive interaction and ACR. CONCLUSIONS: These results provide new insight into the genetic predisposition to renal dysfunction, showing that two polymorphisms in IGF1 and PPARG genes can lead to a reduction in renal filtration rate leading these patients to be exposed to a higher risk of early renal complications.

Risk factors for pre-clinical atherosclerosis in adolescents with type 1 diabetes.

AIMS: To assess whether, besides "traditional" risk factors, overall oxidative stress, oxidized lipoproteins, and glycemic variability are associated with early macro-vascular damage in type 1 diabetes (T1D). METHODS: In 267 children/adolescents with T1D (130 girls, age 9.1-23.0 years) we evaluated: derivatives of reactive oxygen metabolites [d-ROMs], serum total antioxidant capacity [TAC] and oxidized LDL-cholesterol [oxLDL]; markers of early vascular damage (Lipoprotein-associated phospholipase A2 [Lp-PLA2], z-score of carotid intima-media thickness [z-cIMT] and carotid-femoral pulse wave velocity [z-PWV]); CGM metrics of four weeks preceding the visit, central systolic/diastolic blood pressures (cSBP/cDBP), and HbA1c, z-score of BP (z-SBP/z-DBP) and circulating lipids longitudinally collected since T1D onset.. Three general linear models were built with z-cIMT, z-PWV adjusted for current cDBP, and Lp-PLA2 as independent variables. RESULTS: The z-cIMT was associated with male gender (B = 0.491, η2 = 0.029, p = 0.005), cSBP (B = 0.023, η2 = 0.026, p = 0.008) and oxLDL (B = 0.022, η2 = 0.022, p = 0.014). The z-PWV was associated with diabetes duration (B = 0.054, η2 = 0.024, p = 0.016), daily insulin dose (B = 0.52, η2 = 0.018, p = 0.045), longitudinal z-SBP (B = 0.18, η2 = 0.018, p = 0.045) and dROMs (B = 0.003, η2 = 0.037, p = 0.004). Lp-PLA2 was associated with age (B = 0.221, η2 = 0.079, p = 3*10-6), oxLDL (B = 0.081, η2 = 0.050, p = 2*10-4), longitudinal LDL-cholesterol (B = 0.031, η2 = 0.043, p = 0.001) and male gender (B = -1.62, η2 = 0.10, p = 1.3*107). CONCLUSIONS: Oxidative stress, male gender, insulin dose, diabetes duration and longitudinal lipids and blood pressure, contributed to the variance of early vascular damage in young patients with T1D.

Genetic Variation in Antioxidant Response Modulates the Level of Oxidative Stress in Youth with Type 1 Diabetes and Poor Glycemic Control.

BACKGROUND: The minor allele of the single nucleotide polymorphism (SNP) rs2364723 of NFE2L2, a gene encoding a master antioxidant transcription factor, has been associated with poor cardiovascular outcomes and with complications of type 2 diabetes. We assessed the association between rs2364723 of NFE2L2 and oxidative stress in children/adolescents with type 1 diabetes (T1D). METHODS: In 384 children/adolescents with T1D (age 15.7 ± 3.2 years, 207 males), we assessed the oxidative stress by measuring the concentration of derivatives of reactive oxygen metabolites (d-ROMs) and we genotyped the rs2364723 SNP by real time polymerase chain reaction. RESULTS: The concentration of d-ROMs was 372.8 ± 64.6 Carratelli units. The minor genotype (CC) of rs2364723 at NFE2L2 was associated with higher concentration of derivatives of d-ROMs in the subgroup with HbA1c ≥ 8% (B = 47.85, p for genotype ∗ HbA1c interaction = 0.019). CONCLUSIONS: The carriers of the minor genotype of rs2364723 may have increased oxidative stress compared to their counterparts with other genotypes, especially in case of poor glycemic control. This observation needs to be replicated and confirmed in larger independent cohorts of youth with T1D.

FADS cluster variants are associated with insulin sensitivity in children and adolescents with overweight and obesity.

Changes in the desaturation activity of LC-PUFAs may influence insulin sensitivity by modulating the relative abundance of omega-3. The aim of this cross-sectional study was to assess the association between genetic variants of fatty acid desaturase cluster genes (FADS1, FADS2, FADS3) and insulin sensitivity in a cohort of children and adolescents with obesity. Anthropometric evaluation, lipid profile, glucose metabolism parameters and the genotype of rs1535 on FADS2 gene were assessed. In 162 obese children and adolescents (12.6 ± 2.3 years; BMI 30.9 ± 7.3), we found a significant association between an index of insulin sensitivity, i.e., Matsuda index, and rs1535 (B = -0,192; p = 0.008), BMI (B = -0,003; p < 0.001), and triglycerides (B = -0,034; p < 0.001), independent of age and sex [R² = 0.35; p = <0.001]. In conclusion, FADS cluster variants were associated with insulin sensitivity in a population of children and adolescents with obesity, contributing to identify individuals who may benefit from personalised prevention and treatment nutritional strategies since childhood.

Serum zonulin as an index of glucose dysregulation in children and adolescents with overweight and obesity.

Increased intestinal permeability has an important role in metabolic dysregulation. In this cross-sectional study, we examined whether serum intestinal permeability marker zonulin and related pro-inflammatory molecules were associated with the oral disposition index, a predictor for the development of type 2 diabetes, in a cohort of children and adolescents with overweight and obesity. Ninety-two children and adolescents were recruited [Male: 43; 12.7 (2.35) years; BMI SDS: 2.7 (0.96)]. Anthropometric and clinical parameters, lipid profile, glucose metabolism and plasma levels of zonulin, lipopolysaccharide-binding protein and Interleukin-6 were measured. We found an association between oral disposition index and zonulin (ß = -0.243; p = 0.019) and age (ß = -0.307; p = 0.004), independent of sex and BMI SDS [R2  = 0.16; p = 0.005]. Our results show an association between serum zonulin concentration and oral disposition index supporting the hypothesis of increased intestinal permeability as a possible risk factor for glucose metabolism dysregulation in children and adolescents with obesity.

Oxidative stress in youth with type 1 diabetes: Not only a matter of gender, age, and glycemic control.

AIMS: We assessed whether oxidative stress (OS) is increased in children/adolescents with type 1 diabetes (T1D) compared to healthy peers. Moreover, we searched for OS predictors in the T1D population. METHODS: We compared the concentration of serum derivatives of reactive oxygen metabolites (d-ROMs) in 412 children/adolescents with T1D (3.6-23.5 years old) to that of 138 healthy children/adolescents (1.2-19.2 years old) by ANOVA adjusted for age, gender, and BMI z-score (z-BMI). Applying a general linear model, in a subgroup of 331 patients using continuous glucose monitoring, we searched for predictors of d-ROMs among 3-day, 2-week, and 4-week metrics of glucose control and variability, such as mean blood glucose, percent time in range (70-180 mg/dl,TIR70-180), coefficient of variation, and others, as well as among conventional cardiovascular risk factors like current and average HbA1c, z-BMI, blood pressure percentiles, and lipid concentrations recorded retrospectively over the entire follow-up period. RESULTS: D-ROMs levels were significantly higher in children/adolescents with T1D compared to controls [371.9 (64.2) versus 324.9 (46.3), p < 10-16]. Sex (B = 49.1, ƞ2 = 0.14, p = 1.3 * 10-9), age < 12 years in boys (B = 79.4, ƞ2 = 0.074, p = 10-7),3-day TIR70-180 (B = -0.87, ƞ2 = 0.048, p = 6.5 * 10-5), and z-BMI (B = 7.4, ƞ2 = 0.016, p = 0.022) predicted d-ROMs with an overall R2 of 0.278. CONCLUSIONS: OS is increased in youth with T1D and only partially predicted by gender, age, glucose control, and anthropometry. Other potential determinants of OS in this population should be targeted in future studies.

13C/12C breath test ratio after the ingestion of a meal naturally enriched with (13C)carbohydrates is a surrogate marker of insulin resistance and insulin sensitivity in children and adolescents with Type 1 Diabetes.

AIMS: To test the hypotheses that exogenous carbohydrate oxidation affects postprandial glycaemic profiles and 13C/12C breath test could be used for estimating insulin resistance (IR) and insulin sensitivity (IS) in youths with Type 1 Diabetes (T1D). METHODS: Non-randomized, cross-sectional study for repeated measures; fifteen youths (11-15 years) with T1D were enrolled. Respiratory exchanges were measured by indirect calorimetry after the ingestion of a mixed meal [13% protein, 29% fat, 58% carbohydrate (CHO; naturally enriched with [13C]carbohydrates)]. Total and exogenous CHOs oxidation was calculated by indirect calorimetry and 13C/12C breath test. IR and IS were calculated using estimated Glucose Disposal Rate (eGDR) and Insulin Sensitivity Score (ISS). RESULTS: The blood glucose Area Under the Curve (BG-AUC) was significantly associated with the amount of exogenous CHOs oxidized (r = -0.67, p < 0.02) when adjusting for CHOs intake and %fat mass. A direct correlation between eGDR and ISS with exogenous CHOs oxidized (r = 0.70, p < 0.02; r = 0.61, p < 0.05 respectively) and with the differential of 13C/12C enrichment in the expired at breath test (r = 0.59, p < 0.05; r = 0.62, p < 0.05), was found. CONCLUSIONS: Assessing the capacity to oxidize exogenous CHOs (estimated by the differential of 13C/12C enrichment in the expired air at the breath test) could be used as a non-invasive surrogate marker of IR and IS in youths with T1D.

Policaptil Gel Retard Intake Reduces Postprandial Triglycerides, Ghrelin and Appetite in Obese Children: A Clinical Trial.

The aim of this study is to test the hypothesis that the intake of Policaptil Gel Retard® (PGR) is able to affect appetite, metabolic and hormonal postprandial profile in obese children. 46 obese children were randomly assigned to treatment with PGR or placebo, in a double blind clinical trial. Two PGR tablets or placebo were given in fasting condition, before the ingestion of a mixed meal (15 kcal/kg lean body mass). Blood samples were taken at baseline and for 4 hours, for measuring blood lipids, glucose, insulin, ghrelin, and glucagon like peptide-1 (GLP-1). Appetite was quantified using a visual analog scale. Children assuming PGR had a significantly lower increase of postprandial triglycerides (area under the curve (AUC): 3021 (2879) vs. 5038 (3738) mg × 240 min/Dl) and appetite (-234 (274) vs. 36 (329)) than children assuming placebo. The AUC of ghrelin was significantly lower after PGR ingestion, than after placebo (-8179 (8073) vs. -2800 (7579) pg × 240 min/mL). Blood glucose, insulin, non-esterified fatty acids (NEFA) and GLP-1 profiles were not significantly different in the two groups. In conclusion, a single intake of two tablets of PGR was associated with a significant reduction of appetite, ghrelin, and triglycerides in the postprandial period in obese children. Further investigation will assess if a chronic intake of PGR may affect body weight and glucose metabolism.

Systemic anti-oxidant capacity is inversely correlated with systolic blood pressure and pulse pressure in children with obesity.

BACKGROUND AND AIMS: Oxidative stress leading to endothelial dysfunction is a candidate driver of obesity-related hypertension. We aimed to assess whether the total anti-oxidant capacity (TAC) was associated with blood pressure in children/adolescents with obesity. METHODS AND RESULTS: One hundred and fifty-two children/adolescents with obesity (79 boys; age 11.9+/-2.5 years) underwent blood drawing for the assessment of TAC, lipids and HOMA-IR. Blood pressure was measured and classified according to the latest American Academy of Pediatrics Guidelines. Serum TAC was measured by a commercial kit (Sigma-Aldrich). The average TAC was 1.11+/-0.4 mMol/Trolox equivalents. Systolic blood pressure was predicted by TAC (B = -5.8, p = 0.003), z-BMI (B = 2.39, p = 0.008), height [cm] (B = 0.38, p < 0.001) and diastolic blood pressure (B = 0.56, p < 0.001). Diastolic blood pressure was predicted by age [years] (B = 0.58, p = 0.001), log-HOMA-IR (B = 3.0, p = 0.002), and systolic blood pressure (B = 0.26, p < 0.001), but not by TAC. The pulse pressure was predicted only by TAC (B = - 6.6, p = 0.002), and height [cm] (B = 0.42, p < 0.001). Overall "elevated blood pressure + hypertension" or hypertension alone were not associated with TAC. However, systolic "elevated blood pressure + hypertension" was associated with TAC (OR = 0.4 [0.1-0.9], p = 0.037), and z-BMI (OR = 2.1 [1.3-3.6], p = 0.004). CONCLUSION: The systemic anti-oxidant capacity is inversely associated with systolic blood pressure and pulse pressure in children and adolescents with obesity.

Vitamin D affects insulin sensitivity and ß-cell function in obese non-diabetic youths.

OBJECTIVE: Vitamin D may potentially play a central role in glucose homeostasis and ß-cell function (BCF), although studies are not consistent. Aim of our study was to test the hypotheses of a direct relationship between vitamin D, insulin sensitivity (IS) and BCF in overweight and obese non-diabetic children. DESIGN AND METHODS: Cross-sectional study carried out at the Childhood Obesity Outpatient Clinic, University Hospital of Verona. One hundred twenty-two Caucasian overweight and obese children (age: 12.8 ± 0.2 years) were enrolled. Exclusion criteria: genetic or endocrine causes of obesity, chronic diseases or therapies. Patients underwent oral glucose tolerance test. HOMA-IR, Matsuda index and insulinogenic index were calculated. BCF was reconstructed by mathematical modeling and described by Derivative and Proportional Control. Total 25-hydroxyvitamin D and vitamin D-binding protein (VDBP) were measured. Two SNPs (rs4588 and rs7041) in the VDBP gene were studied, and bioavailable vitamin D (BVD) was calculated. RESULTS: Hypovitaminosis D was documented in 90% of patients. Forty-seven subjects were homozygous for both SNPs. Total vitamin D was positively correlated with Matsuda index (P = 0.002), VDBP (P = 0.045), and negatively with BMI SDS (P = 0.043), HOMA-IR (P = 0.008), HOMA-B (P = 0.001), IGI (P = 0.007), derivative control (P = 0.036) and proportional control (P = 0.018). Total vitamin D, adjusted for age, gender, BMI SDS, puberty and seasonality of vitamin D measurement, was a predictor of Matsuda index, HOMA-IR, HOMA-B, IGI, proportional control (all P < 0.05). BVD was positively correlated with total vitamin D (P < 0.001) and negatively with BMI SDS (P = 0.041). CONCLUSIONS: Hypovitaminosis D negatively influences BCF and IS, suggesting that vitamin D levels might be implicated in glucose metabolism impairment in overweight and obese individuals.

Contribution of a genetic risk score to clinical prediction of hepatic steatosis in obese children and adolescents.

BACKGROUND: Nonalcoholic fatty liver disease (NAFLD) is the commonest liver disease in children and adolescents in Western countries. Complex traits arise from the interplay between environmental and genetic factors in the pathogenesis of NAFLD. AIMS: We examined the association between NAFLD and eleven single nucleotide polymorphisms (SNPs) at genetic loci potentially associated with liver damage (GCKR, MBOAT7, GPR120), oxidative stress (SOD2), lipid metabolism (PNPLA3, TM6SF2, LPIN1, ELOVL2, FADS2, MTTP) and fibrogenesis (KLF6) in a paediatric population. A genetic risk score (GRS) was performed taking into account both these SNPs and clinical risk factors. METHODS: We recruited a cohort of 514 obese children and adolescents (mean age [±SD]: 11.2 ±â€¯2.8 years, z-BMI 3.3 ±â€¯0.8). NAFLD was identified by ultrasonography. Genotyping was performed by TaqMan-based RT-PCR system. RESULTS: The overall prevalence of NAFLD was 67.5% (347 patients). Among the eleven genotyped SNPs, the genetic variants in TM6SF2 rs58542926 (OR = 4.13, p = 0.002), GCKR rs1260326 (OR = 1.53, p = 0.003), PNPLA3 rs738409 (OR = 1.58, p = 0.004) and ELOVL2 rs2236212 (OR = 1.34, p = 0.047) were significantly associated with a higher risk of NAFLD. Addition of a 11-polymorphism GRS to established clinical risk factors significantly (albeit modestly) improved the discriminatory capability of the regression model for predicting the risk of NAFLD (with SNPs C-statistic 0.81 [95%CI 0.75-0.88] vs. 0.77 [0.70-0.84] without SNPs; p = 0.047). CONCLUSIONS: NAFLD was strongly associated with three genetic variants, TM6SF2 rs58542926, PNPLA3 rs738409 and GCKR rs1260326, and more slightly with ELOVL2 rs2236212, in obese children and adolescents. Addition of a 11-polymorphism GRS to clinical risk factors improved the predictability of NAFLD.

"IGT-like" status in normoglucose tolerant obese children and adolescents: the additive role of glucose profile morphology and 2-hours glucose concentration during the oral glucose tolerance test.

OBJECTIVE: To assess whether combining glucose shape and 2-h glucose concentration during an oral glucose tolerance test (OGTT) may help identifying normal glucose tolerant obese children/adolescents with an impaired glucose tolerant (IGT)-like metabolic profile in term of insulin sensitivity (Matsuda index) and ß-cell function (disposition index: DI). SUBJECTS, METHODS, AND MAIN OUTCOME MEASURE: In total, 654 non-diabetic obese children/adolescents underwent a 2 h OGTT. The whole population was classified according to 2-hour plasma glucose ( < 100, 100-119, 120-139, 140-200 mg/dL) and glucose shape (monophasic or biphasic). Monophasic morphology was characterized by an increase in OGTT glucose concentration followed by a decline of at least 4.5 mg/dL, a biphasic response was defined as a decrease in glucose after an initial increase, followed by a second increase of ≥ 4.5 mg/dL. A subset of 69 participants had also a prolonged OGTT to estimate ß-cell function in "biphasic" versus "monophasic" patients. RESULTS: Matsuda index and DI decreased across 2-h glucose categories (both p < 0.001) and were lower in monophasic compared with biphasic children, independently of 2-h glucose category (both p < 0.001, both p for glucose category×shape interaction > 0.05). Normal glucose tolerant children with 2-h glucose of 120-139 mg/dl and monophasic glucose shape did not differ from IGT children, as regards Matsuda index and DI (both p > 0.05). Among children undergoing a prolonged OGTT, those with a monophasic glucose shape had worse ß-cell function, modeled as proportional control, than those with a biphasic shape (p = 0.031). CONCLUSIONS: A monophasic OGTT glucose shape is associated with unfavorable glucose metabolism independently of 2-h glucose concentration. Children combining monophasic shape and normal-high 2-h glucose have an IGT-like glucose metabolism.

Minor diplotypes of FMO3 might protect children and adolescents from obesity and insulin resistance.

In order to assess whether flavin-containing monooxygenase-3 (FMO3) might be involved in early cardiovascular risk, we assessed adiposity and traditional metabolic variables in children/adolescents grouped according to their genotypes in two FMO3 exonic polymorphisms, rs2266782 (E158K) and rs2266780 (E308G), which are in linkage disequilibrium and have been associated with decreased FMO3 activity. Among 776 children/adolescents (10.8 ± 2.2 years) recruited from the general population (452) and from our obesity outpatient clinic (324), the 68 carrying either the 158K-308G/158K-308E or the 158K-308G/158K-308G diplotype had lower mean z-BMI and prevalence of obesity compared to their 708 peers carrying any of the other diplotypes (0.39 vs 0.80, p = 0.01; OR = 0.39[0.17-0.87], p = 0.018, respectively), and to the sub-sample of 303 children carrying the major diplotype (158E-308E/158E-308E) (0.39 vs 0.87, p = 0.008; OR = 0.35[0.16-0.81], p = 0.014, respectively). They also had lower z-BMI-adjusted lnHOMA-IR compared to all the other children (0.75 vs 0.97, p = 0.001) and those carrying the major diplotype, (0.75 vs 0.98, p = 0.03), as well as lower z-BMI-adjusted iln-triglycerides compared to all the other children (3.98 vs 4.17, p = 0.037). These associations provide the first evidence that FMO3 may be involved in early body weight, insulin sensitivity, and lipid regulation in humans.

Association between intestinal permeability and faecal microbiota composition in Italian children with beta cell autoimmunity at risk for type 1 diabetes.

BACKGROUND: Pancreatic organ-specific autoimmunity in subjects at risk for type 1 diabetes (T1D) is associated with increased intestinal permeability and an aberrant gut microbiota, but these factors have not yet been simultaneously investigated in the same subjects. Thus, the aim of this study was to assess both intestinal permeability and gut microbiota composition in an Italian sample of children at risk for T1D. METHODS: Ten Italian children with beta cell autoimmunity at risk for T1D and 10 healthy children were involved in a case-control study. The lactulose/mannitol test was used to assess intestinal permeability. Analysis of microbiota composition was performed using polymerase chain reaction followed by denaturing gradient gel electrophoresis, based on the 16S rRNA gene. RESULTS: Intestinal permeability was significantly higher in children at risk for T1D than in healthy controls. Moreover, the gut microbiota of the former differed from that of the latter group: Three microorganisms were detected - Dialister invisus, Gemella sanguinis and Bifidobacterium longum - in association with the pre-pathologic state. CONCLUSIONS: The results of this study validated the hypothesis that increased intestinal permeability together with differences in microbiota composition are contemporaneously associated with the pre-pathological condition of T1D in a sample of Italian children. Further studies are necessary to confirm the microbial markers identified in this sample of children as well as to clarify the involvement of microbiota modifications in the mechanisms leading to increased permeability and the autoimmune mechanisms that promote diabetes onset. Copyright © 2016 John Wiley & Sons, Ltd.

Analysis of the d3-growth hormone receptor polymorphism in large cohorts of small, appropriate and large for gestational age newborns.

BACKGROUND: Several studies evidenced a possible role of the d3-Growth Hormone Receptor (GHR) polymorphism in fetal growth. The GHR genotype distribution was studied in small (SGA) and appropriate (AGA) for gestational age newborns but never in the large (LGA) for gestational age babies. The aim of this study was to evaluate the frequencies of this polymorphism in a large cohort of SGA, AGA and LGA newborns. METHODS: A total of 536 healthy newborns, randomly selected among the infants referred to the Italian North-Eastern centre for endocrinological and metabolic newborn screening, were enrolled: 192 SGA, 200 LGA and 144 AGA. Weight was recorded at birth. Isoforms of d3-GHR gene (fl/fl, d3/fl, and d3/d3) were analysed. RESULTS: The analysis of the GHR genotype evidenced a lower frequency of the d3/d3 genotype in SGA cohort compared to the AGA population (P=0.005), or to the total population (P=0.035). No differences were found in the genotypic distribution between LGA and AGA population (P=0.373), or between LGA and the whole population (P=0.292). CONCLUSIONS: d3/d3 GHR genotype was found twice as frequent in AGA and LGA cohorts compared to SGA subjects, whereas no significant differences in the frequency distribution of the GHR genotypes between LGA and AGA newborns were detected. The data leads to the exclusion of the GHR exon 3 deletion polymorphism as a possible genetic factor leading to LGA pregnancies.

The recurrent causal mutation for osteogenesis imperfecta type V occurs at a highly methylated CpG dinucleotide within the IFITM5 gene.

Recent studies have identified the molecular defect underlying autosomal dominant osteogenesis imperfecta (OI) type V. Unlike all other OI types, which are characterized by high genetic heterogeneity, OI type V appears consistently associated to a unique de novo C>T transition within the 5' UTR of the IFITM5 gene. Although the precise frequency of OI type V is not known, this recurrent base substitution may well represent a mutational hotspot in the human genome. We show that it occurs at a CpG dinucleotide that is highly methylated in several tissues and particularly in the sperm DNA, suggesting a mutational mechanism common to other de novo recurrent dominant mutations.

Cardiac valve disease: an unreported feature in Ehlers Danlos syndrome arthrocalasia type?

Ehlers Danlos syndrome (EDS) athrocalasia type (type VII), is characterized by joint hypermobility, skin hyperextensibility and tissue fragility. No heart involvement has been reported. Two forms have been described: type VII A and VII B. The abnormally processed collagen α2(I) and the skipping of the exon 6 in COL1A2 gene are typically detected in EDS type VII B. We describe a seven-year old female, with a phenotype consistent with EDS type VII B and a diagnosis further confirmed by biochemical and molecular analyses. Cardiac ultrasound showed normal data in the first year of life. When she was 5 years old, the patient developed mitral valve regurgitation, and aortic and tricuspidal insufficiency at 7 years of age. To our knowledge, this is the first report of cardiac valvular involvement in EDS VII B. This feature probably has been underreported for the limited follow-up of the patients. Echocardiography might be warranted in the clinical assessment of EDS VII patients.

Lack of expression of SERPINF1, the gene coding for pigment epithelium-derived factor, causes progressively deforming osteogenesis imperfecta with normal type I collagen.

Osteogenesis imperfecta (OI) is a clinically heterogeneous heritable connective tissue disorder, characterized by low bone mass and reduced strength, which result in susceptibility to fracture and bone deformities. In most cases it is caused by dominant mutations in type I collagen genes, COL1A1 and COL1A2. Recessive forms, which collectively account for approximately 5% of cases of osteogenesis imperfecta detected in North America and Europe, are caused instead by mutations in various genes coding for proteins involved in collagen posttranslational modifications, folding, and secretion. A novel disease locus, SERPINF1, coding for pigment epithelium-derived factor (PEDF), has been found recently. In SERPINF1 mutants described so far, synthesis, posttranslational modification, and secretion of type I collagen were reported to be normal. Here we describe three siblings born to consanguineous parents, who show an initially mild and then progressively worsening form of OI with severe deformities of the long bones. They are homozygous for a frameshift mutation in exon 4 of the SERPINF1 gene, which leads to lack of the transcription/translation product, likely a key factor in bone deposition and remodeling. Synthesis and secretion of type I collagen are normal. Clinical, radiographic, histological, and histomorphometric data from the proband are reminiscent of the distinctive features of type VI OI.

A novel splicing mutation in FKBP10 causing osteogenesis imperfecta with a possible mineralization defect.

Osteogenesis imperfecta (OI) is a group of hereditary disorders characterized by bone fragility and osteopenia, with a broad spectrum of clinical severity. The majority of cases are dominantly inherited and due to mutations in type I collagen genes, whereas recessive forms are less frequent and attributable to mutations in different genes involved in collagen I post translational modifications and folding (prolyl-3-hydroxylase complex, SERPINH1, FKBP10). We report the case of a patient with an initially mild and then progressively severe form of osteogenesis imperfecta due to a novel homozygous splicing mutation in FKBP10 (intron 8 c.1399+1G>A), which results in aberrant mRNA processing and consequent lack of FKBP65 chaperone. Although this mutation does not affect collagen type I post translational modifications in dermal fibroblasts, the histomorphometric pattern of our patient's bone sample showed a mineralization defect possibly due to the mutation in FKBP10.