Beyond Body Mass Index - Body Composition Assessment by Bioimpedance in Routine Endocrine Practice.

OBJECTIVE: To explore the body composition of pediatric patients referred for endocrine evaluation. METHODS: This real-life observational study conducted between January 2018 and January 2020 included 10 001 clinic visits of 3500 children and adolescents; first visits of 5 to 18-year-old patients were included. Anthropometric data, blood pressure levels, pubertal status, and bioelectrical impedance analysis (BIA, Tanita MC-780 MA) were extracted from medical files. Excluded from the analysis were patients participating in other studies. RESULTS: A total of 1001 patients (48% boys, mean age 11.3 ± 3.4 years, 33.5% prepubertal) were included. Mean anthropometric z-scores were normal and similar for boys and girls. Sex differences in body composition were as follows: boys had lower fat percentage, lower truncal fat percentage, higher appendicular skeletal muscle mass, and a higher muscle-to-fat ratio (MFR) than girls (P < .001 for all). MFR correlated with body mass index-standard deviation scores (BMI-SDS) in overweight/obese patients (r = -0.558, P < .001), although not in underweight patients. Systolic blood pressure (SBP) correlated with BMI-SDS in overweight/obese patients (r = 0.262, P < .001), although not in underweight patients. Diastolic blood pressure (DBP) did not correlate with BMI-SDS in either group of extreme weight status. MFR correlated with SBP and DBP in overweight/obese patients (r = -0.230, P < .001 and r = -0.141, P = .018, respectively) as well as in underweight patients (r = 0.331, P < .001 and r = 0.264, P = .005, respectively). CONCLUSIONS: Our findings support BIA for a more refined characterization of patients referred for endocrine evaluation than BMI-SDS. MFR may be a better surrogate marker of blood pressure levels than BMI-SDS in both underweight and overweight/obese pediatric patients.

The heritability of body composition.

BACKGROUND: Physical growth during childhood and adolescence is influenced by both genetic and environmental factors. Heritability, the proportion of phenotypic variance explained by genetic factors, has been demonstrated for stature and weight status. The aim of this study was to explore the heritability of body composition. METHODS: A real-life, observational study of the children and adolescents referred to the Endocrine Unit in a tertiary medical center. In January 2018, body composition by means of bioimpedance analysis (BIA) was implemented as part of the standard intake assessment of subjects referred for endocrine consultation. The clinic BIA database was searched for subjects with the term "observation of growth" as the sole reason for referral. BIA of 114 triads of healthy subjects aged 5-18 years and their parents were analyzed. The BIA report included the following data: fat mass, fat percentage, truncal fat percentage and muscle mass. Calculated variables included: appendicular skeletal muscle mass (ASMM = the sum of muscle mass of four limbs), muscle-to-fat ratio [MFR = ASMM (kg)/fat mass (kg)] and sarcopenic index [(SI = ASMM(kg)/height (meter)²]. Data collection from medical files included pubertal stage and home address for socioeconomic position grading. RESULTS: There were sex differences in body composition parameters in both the prepubertal and pubertal subjects. The boys among the prepubertal subjects had a lower fat percentage on average than girls (p = 0.020). Among the adolescents, boys on average had lower fat percentage (p = 0.011), higher sarcopenic index (p = 0.021), and higher muscle-to-fat ratio (p < 0.001), than adolescent girls. Correlation analyses between body composition parameters of all participants revealed significant correlations in the sarcopenic index of prepubertal children and their parents (boys-fathers: r = 0.380, p = 0.050; boys-mothers: r = 0.435, p = 0.026; girls-fathers: r = 0.462, p = 0.012; girls-mothers: r = 0.365, p = 0.050) and adiposity indices (fat percentage, truncal fat percentage and muscle-to-fat ratio) of prepubertal boys and their mothers (r = 0.438, p = 0.025; r = 0.420, p = 0.033, and r = 0.478, p = 0.014, respectively). There were no associations between body composition parameters of adolescents and their parents. Socioeconomic position adversely affected fat percentage in adolescent girls and mothers. CONCLUSIONS: Heritable body composition traits were demonstrated in childhood but not in adolescence, suggesting that environmental influence has a more telling effect during teenage years.

Maternal-fetal vitamin D receptor polymorphisms significantly associated with preterm birth.

PURPOSE: Preterm birth (PTB) is a complex trait with strong genetic background, whose etiology is not fully understood. It was recently suggested that pregnancy duration is affected by fetal genetic variation even more than by the maternal genome. Vitamin D receptor (VDR) is involved in embryonic implantation and fertility. We studied the association between both maternal and neonatal vitamin D receptor (VDR) genetic variation and PTB. METHODS: Maternal and fetal (umbilical cord) DNA was isolated from Jewish Israeli idiopathic preterm newborns (24-36 weeks, n = 146) and control term newborns (>37 weeks, n = 229). Maternal and fetal VDR polymorphisms (FokI, ApaI, BsmI, TaqI) were analyzed by restriction fragment length polymorphism analysis. Using SPSS analysis to correlate VDR genotypes with phenotypic variation: pregnancy duration, preterm birth and spontaneous miscarriages, adjusted for gravidity, parity and gender of newborn. RESULTS: Women homozygous to VDR ApaI (AA) genotype had significant twofold increase risk for PTB [OR 1.973, (CI) 1.183-3.289, p = 0.009] compared to heterozygous women. Male newborns had significant (p < 0.05) 1.73-fold increase of PTB. Women with history of previous (≥1) spontaneous miscarriage had a significant increased risk for PTB if their newborn carried either of the VDR BsmI homozygous (BB or bb) genotypes compared to the heterozygous (Bb) genotype [OR 6.857, (CI) 1.273-36.934, p = 0.018 and OR 9.231, (CI) 1.753-48.618, p = 0.008, respectively], or VDR ApaI homozygous (AA or aa) genotype compared to heterozygous (Aa) genotype [OR 4.33, (CI) 1.029-18.257, p = 0.046 and OR 7.2, (CI) 1.34-38.917, p = 0.021, respectively]. CONCLUSIONS: We show association between maternal and fetal VDR genotype variants with PTB.

Looking for the skeleton in the closet-rare genetic diagnoses in patients with diabetes and skeletal manifestations.

AIMS: The precision medicine approach of tailoring treatment to the individual characteristics of each patient has been a great success in monogenic diabetes subtypes, highlighting the importance of accurate clinical and genetic diagnoses of the type of diabetes. We sought to describe three unique cases of childhood-onset diabetes in whom skeletal manifestations led to the revelation of a rare type of diabetes. METHODS : Case-scenarios and review of the literature. RESULTS: Case 1: A homozygous mutation in TRMT10A, a tRNA methyltransferase, was identified in a 15-year-old boy with new-onset diabetes, developmental delay, microcephaly, dysmorphism, short stature and central obesity. The progressive apoptosis of pancreatic beta cells required insulin replacement therapy, with increased demand due to an unfavorable body composition. Case 2: Congenital generalized lipodystrophy type 1 was suspected in an adolescent male with an acromegaloid facial appearance, muscular habitus, and diabetes who presented with a pathological fracture in a cystic bone lesion. A homozygous mutation in AGPAT2, an acyl transferase which mediates the formation of phospholipid precursors, was identified. Leptin replacement therapy initiation resulted in a remarkable improvement in clinical parameters. Case 3: A 12-year-old boy with progressive lower limb weakness and pain was diagnosed with diabetic ketoacidosis. Diffuse diaphyseal osteosclerosis compatible with the diagnosis of Camurati-Engelmann disease and a heterozygous mutation in TGFß1 were identified. Preservation of euglycemia by insulin replacement relieved pain, suggesting that the diabetic milieu may have augmented TGFß1 overexpression. CONCLUSION: Unraveling the precise genetic cause for the clinical manifestations led to the prediction of phenotypic manifestations, and enhanced the clinical outcomes.

Maternal and neonatal irisin precursor gene FNDC5 polymorphism is associated with preterm birth.

Irisin is a novel secreted myokine, encoded by the fibronectin type III domain-containing protein 5 (FNDC5) precursor gene. Irisin plays a role in the female reproductive system in pregnancy and in embryonic development, and is associated with fetal size. It is expressed in the ovary, placenta and neonatal cord serum. We studied whether maternal and neonatal FNDC5 genetic polymorphisms are associated with preterm birth (PTB). Blood for DNA analysis was collected from Israeli mothers (n = 315) and from umbilical veins of their respected idiopathic preterm (24-36 weeks) and control term (>37 weeks) newborns (n = 161). Genotypes of maternal and neonatal FNDC5 polymorphisms (rs726344 and rs1746661) were determined by restriction fragment length polymorphism analysis. Genotype-phenotype associations were analyzed using SPSS program. The Frequency of FNCD5 rs726344 G alleles in the Israeli cohort is 82%. We found significant FNCD5 rs726344 genotype frequencies control and PTB groups. Women bearing the FNDC5 rs726344 GG genotype had 2.18 fold ([CI] 1.193-4.008, p = 0.01) higher chance to deliver at term compared to both AG and AA genotypes (adjusting to age, gravidity, parity, weight percentile per gestational age and gender of newborn). Neonates carrying the FNDC5 rs726344 GG genotype had 2.24 fold ([CI] 0.979-5.134, p = 0.05) higher chance to be born at term compared to either AG or AA genotypes (adjusting to parity, previous abortions and weight percentile per gestational age). There was no significant association of the rs1746661 polymorphism with PTB. Thus, we determined FNDC5 polymorphisms frequencies in the Israeli population and demonstrated that maternal and neonatal FNDC5 rs726344 polymorphism is significantly associated with increased risk for PTB.

Maternal and neonatal leptin and leptin receptor polymorphisms associated with preterm birth.

UNLABELLED: Leptin (LEP) and leptin receptor (LEPR) are suggested to play a role in female reproduction and especially in pregnancy Both LEP and LEPR are synthesized by the pregnant female and embryo. The link between genetic polymorphisms of LEP and LEPR and preterm birth (PTB) is unknown. We studied maternal and neonatal LEP and LEPR genetic polymorphisms and the association with PTB. Blood for DNA analysis was collected from Israeli mothers and from venous umbilical of their respected idiopathic preterm newborns (24-36weeks, n=102) and control term newborns (>37weeks, n=158). Genotypes of maternal and neonatal LEP (rs7799039) and LEPR (rs1137101) polymorphisms were analyzed by restriction fragment length polymorphism analysis. Genotype-phenotype association was assayed using SPSS program. We found a significant independent increased risk of PTB for women and neonates bearing the homozygous AA form of LEP genotype; where women carrying AA LEP genotype had 2.53 fold ([CI] 1.367-4.685, p=0.03) and 2.38 fold ([CI] 1.150-4.915, p=0.019) increased risk for PTB compared to AG and GG genotypes, respectively. Neonates carrying the LEP AA genotype had a significant 2.8 fold increased risk for PTB compared to the AG genotype (CI11.040-7.577, p=0.042). Maternal LEPR polymorphism was significantly associated with severe PTB; where women carrying the AA and AG genotypes had a significant 4.32 and 4.76 fold increased risk for severe PTB compared to women carrying the GG genotype (CI=1.090-17.112 and 1.332-17.027, respectively p=0.035). IN CONCLUSION: maternal and neonatal LEP and LEPR polymorphisms are significantly associated with increased risk for PTB.