Association of muscular strength with total and central adiposity in adolescents with intellectual disability.

BACKGROUND: It has been established that for youth without disabilities, muscular strength (MS) is negatively associated with total and central adiposity. However, this relationship has not been clearly established for youth with intellectual disability (ID). The purpose of this study was to examine the association of MS with total and central adiposity in adolescents with ID. METHOD: Participants were 59 adolescents (40 males and 19 females: age 16.29 ± 1.66 years) with ID. Total and central adiposity were evaluated with dual-energy x-ray absorptiometry (DXA), body mass index (BMI), BMI z-score, waist circumference (WC), and conicity index (C-index). MS was evaluated with the score on the Bruininks-Oseretsky Test of Motor Proficiency (range, 0 to 42, with higher scores indicating better performance). Sex-specific maturity offset equations were used to evaluate somatic maturity. Spearman's correlation coefficients and sequential multiple regression were used to examine associations between MS and adiposity. RESULTS: Muscular strength score was negatively associated with BMI (sr = -0.32; P < 0.05), percent body fat (%BF; total, trunk, android and gynoid regions) (sr = -0.51 to -0.58; P < 0.01), and android-to-gynoid fat ratio (sr = -0.29; P < 0.05). After control for somatic maturity and sex, regression analysis indicated that MS score explained 10%-17% of the variance in BMI, BMI z-score, %BF (total, trunk, android and gynoid regions), WC, C-index and android-to-gynoid fat ratio. CONCLUSIONS: These findings suggest that MS is associated with DXA- and anthropometric-determined total and central adiposity among adolescents with ID.

Sex dimorphism of weight and length at birth: evidence based on disorders of sex development.

BACKGROUND: Males have higher weight and length at birth than females. AIM: To verify the influence of the Y chromosome and the action of intrauterine androgens on weight and length at birth of children with Disorders of Sex Development (DSD). SUBJECTS AND METHODS: A cross-sectional and retrospective study. Patients with Turner syndrome (TS), complete (XX and XY), mixed (45,X/46,XY) and partial (XY) gonadal dysgenesis (GD), complete (CAIS) and partial (PAIS) androgen insensitivity syndromes and XX and XY congenital adrenal hyperplasia (CAH) were included. Weight and length at birth were evaluated. RESULTS: Weight and length at birth were lower in TS and mixed GD when compared to XY and XX DSD cases. In turn, patients with increased androgen action (117 cases) had higher weight and length at birth when compared to those with absent (108 cases) and decreased (68 cases) production/action. In birthweight, there was a negative influence of the 45,X/46,XY karyotype and a positive influence of increased androgen and gestational age. In birth length, there was a negative influence of the 45,X and 45,X/46,XY karyotypes and also a positive influence of increased androgen and gestational age. CONCLUSIONS: The sex dimorphism of weight and length at birth could possibly be influenced by intrauterine androgenic action.

Predicting the rate of oxygen uptake from step counts using ActiGraph waist-worn accelerometers in adults with Down syndrome.

BACKGROUND: Step rate predicts ambulatory intensity as reflected in the rate of oxygen uptake (VO2 ) - a measure of energy expenditure. Whether step rate as measured by an accelerometer predicts VO2 in adults with Down syndrome (DS) is unknown. We examined whether step rate predicts VO2 in adults with and without DS. We also developed an equation for predicting VO2 and examined its accuracy. METHOD: Sixteen adults with DS (6 women and 10 men; age 31 ± 15 years) and 19 adults without DS (9 women and 10 men; age 25 ± 6 years) performed standing and walking at their preferred speed, 0.8 and 1.4 m·s-1 . We measured VO2 with a portable spirometer and step rate with a triaxial accelerometer (wGT3X-BT; ActiGraph) on the non-dominant hip, using the low-frequency extension filter. We ran multilevel regression for predicting VO2 from linear and quadratic terms for step rate, group (1 = DS; 0 = non-DS), body mass, height, body mass index (BMI), leg length and sex. We estimated VO2 with the resultant equation and calculated the equation's absolute per cent error, which we compared between groups. RESULTS: VO2 was higher in persons with than without DS only at the fast walking speed (P = 0.018). DS did not predict VO2 . Step rate, step rate squared and BMI were significant predictors of VO2 (P < 0.001; R2  = 0.80). Absolute error across walking speeds was 13.5-18.8% and 11.7-13.4% for adults with and without DS, respectively, and did not differ between groups or speeds. CONCLUSIONS: Step rate, step rate squared and BMI predict VO2 in adults with and without DS. Prediction error does not differ between groups.

Association between serotonin 2C receptor gene (HTR2C) polymorphisms and psychopathological symptoms in children and adolescents.

Serotonin 2C receptors (5HT2C) are involved in serotonin-driven dynamic equilibrium adjustments responsible for homeostatic stability in brain structures that modulate behavior and emotions. Single nucleotide polymorphisms (SNPs) from the serotonin 2C receptor gene (HTR2C) have been associated with several neurological and mental disorders, including abnormalities in cognitive and emotional processes. The aim of this study was to evaluate the association between the rs6318 SNP of the HTR2C gene and behavioral characteristics exhibited by children and adolescents based on the Child Behavior Checklist (CBCL/6-18) inventory. Eighty-five psychiatric outpatients between 8 and 18 years of age underwent genotyping of the rs6318 SNP. The CBCL/6-18 scale was administered to their caregivers. The chi-squared test was used to assess differences in the frequency of C and G alleles of the rs6318 SNP relative to the grouped CBCL/6-18 scores; significance level was 5%. The presence of the G allele of rs6318 was found to be associated with characteristics of aggressive behavior and social problems, and aggressive behavior was found to be associated with heterozygosis in females. These findings contribute to the identification of mental and behavioral phenotypes associated with gene expression.

Association between serotonin 2C receptor gene (HTR2C) polymorphisms and psychopathological symptoms in children and adolescents

Serotonin 2C receptors (5HT2C) are involved in serotonin-driven dynamic equilibrium adjustments responsible for homeostatic stability in brain structures that modulate behavior and emotions. Single nucleotide polymorphisms (SNPs) from the serotonin 2C receptor gene (HTR2C) have been associated with several neurological and mental disorders, including abnormalities in cognitive and emotional processes. The aim of this study was to evaluate the association between the rs6318 SNP of the HTR2C gene and behavioral characteristics exhibited by children and adolescents based on the Child Behavior Checklist (CBCL/6-18) inventory. Eighty-five psychiatric outpatients between 8 and 18 years of age underwent genotyping of the rs6318 SNP. The CBCL/6-18 scale was administered to their caregivers. The chi-squared test was used to assess differences in the frequency of C and G alleles of the rs6318 SNP relative to the grouped CBCL/6-18 scores; significance level was 5%. The presence of the G allele of rs6318 was found to be associated with characteristics of aggressive behavior and social problems, and aggressive behavior was found to be associated with heterozygosis in females. These findings contribute to the identification of mental and behavioral phenotypes associated with gene expression.

Two Novel Mutations in the Thyroid Hormone Receptor ß in Patients with Resistance to Thyroid Hormone (RTH ß): Clinical, Biochemical, and Molecular Data.

The syndrome of resistance to thyroid hormone (RTH ß) is an inherited disorder characterized by variable tissue hyposensitivity to 3,5,30-L-triiodothyronine (T(3)), with persistent elevation of free-circulating T(3) (FT(3)) and free thyroxine (FT(4)) levels in association with nonsuppressed serum thyrotropin (TSH). Clinical presentation is variable and the molecular analysis of THRB gene provides a short cut diagnosis. Here, we describe 2 cases in which RTH ß was suspected on the basis of laboratory findings. The diagnosis was confirmed by direct THRB sequencing that revealed 2 novel mutations: the heterozygous p.Ala317Ser in subject 1 and the heterozygous p.Arg438Pro in subject 2. Both mutations were shown to be deleterious by SIFT, PolyPhen, and Align GV-GD predictive methods.

Secular trends of height, weight and BMI in young adult Brazilian military students in the 20th century.

BACKGROUND: Secular trends of increasing weight and height over past centuries are well documented in developed countries. However, these data are still scarce in developing countries such as Brazil. AIM: To verify the secular trends of height, weight and body mass index (BMI) of military students from Brazilian Army schools who were born between the 1920s and 1990s. SAMPLE AND METHODS: A retrospective study was performed, which included a survey of data from the files of two Army schools. The sample was composed of subjects aged between 18-20 years old. RESULTS: The study analysed 2169 heights and 1741 weights and BMIs. During the evaluation period, height increased 7.3 cm, weight 9.8 kg and BMI 1.8 kg/m(2). The most significant gains were observed in subjects born from the 1920s to the 1940s and the 1960s to the 1970s. CONCLUSION: Secular trends of growth in military students born in the 20th century were positive in Brazil, although increases were not constant decade-by-decade.

Abnormalities in body composition and nutritional status in HIV-infected children and adolescents on antiretroviral therapy.

This cross-sectional study aimed to compare growth, nutritional status and body composition outcomes between a group of 94 HIV-infected children and adolescents on antiretroviral therapy (ART) and 364 healthy controls, and to evaluate their association with clinical and lifestyle variables within the HIV-infected group. When compared with the control group, HIV patients had higher risk of stunting (odds ratio [OR] 5.33, 95% confidence interval [CI]: 2.83-10.04) and thinness (OR 4.7, 95% CI: 2.44-9.06), higher waist-to-hip ratios (medians 0.89 versus 0.82 for boys and 0.90 versus 0.77 for girls, P < 0.001), and lower prevalence of overweight or obesity (OR 0.33, 95% CI: 0.14-0.78). Protease inhibitor usage was associated with thinness (OR 3.51, 95% CI 1.07-11.44) and lipoatrophy (OR 3.5, 95% CI 1.37-8.95). HIV-infected children on ART showed significant nutritional status and body composition abnormalities, consistent with the severity of vertical HIV infection and the consequences of prolonged ART.

The novel p.E89K mutation in the SRY gene inhibits DNA binding and causes the 46,XY disorder of sex development

Male sex determination in humans is controlled by the SRY gene, which encodes a transcriptional regulator containing a conserved high mobility group box domain (HMG-box) required for DNA binding. Mutations in the SRY HMG-box affect protein function, causing sex reversal phenotypes. In the present study, we describe a 19-year-old female presenting 46,XY karyotype with hypogonadism and primary amenorrhea that led to the diagnosis of 46,XY complete gonadal dysgenesis. The novel p.E89K missense mutation in the SRY HMG-box was identified as a de novo mutation. Electrophoretic mobility shift assays showed that p.E89K almost completely abolished SRY DNA-binding activity, suggesting that it is the cause of SRY function impairment. In addition, we report the occurrence of the p.G95R mutation in a 46,XY female with complete gonadal dysgenesis. According to the three-dimensional structure of the human SRY HMG-box, the substitution of the conserved glutamic acid residue by the basic lysine at position 89 introduces an extra positive charge adjacent to and between the positively charged residues R86 and K92, important for stabilizing the HMG-box helix 2 with DNA. Thus, we propose that an electrostatic repulsion caused by the proximity of these positive charges could destabilize the tip of helix 2, abrogating DNA interaction.

The novel p.E89K mutation in the SRY gene inhibits DNA binding and causes the 46,XY disorder of sex development.

Male sex determination in humans is controlled by the SRY gene, which encodes a transcriptional regulator containing a conserved high mobility group box domain (HMG-box) required for DNA binding. Mutations in the SRY HMG-box affect protein function, causing sex reversal phenotypes. In the present study, we describe a 19-year-old female presenting 46,XY karyotype with hypogonadism and primary amenorrhea that led to the diagnosis of 46,XY complete gonadal dysgenesis. The novel p.E89K missense mutation in the SRY HMG-box was identified as a de novo mutation. Electrophoretic mobility shift assays showed that p.E89K almost completely abolished SRY DNA-binding activity, suggesting that it is the cause of SRY function impairment. In addition, we report the occurrence of the p.G95R mutation in a 46,XY female with complete gonadal dysgenesis. According to the three-dimensional structure of the human SRY HMG-box, the substitution of the conserved glutamic acid residue by the basic lysine at position 89 introduces an extra positive charge adjacent to and between the positively charged residues R86 and K92, important for stabilizing the HMG-box helix 2 with DNA. Thus, we propose that an electrostatic repulsion caused by the proximity of these positive charges could destabilize the tip of helix 2, abrogating DNA interaction.

Comparison of bone quantity by ultrasound measurements of phalanges between white and black children living in Paraná, Brazil, with Europeans

The objective of this study was to determine bone quantity by ultrasound measurements of the proximal finger phalanges (AD-SoS = amplitude-dependent speed of sound) of healthy Brazilian schoolchildren living in Paraná, Brazil and to compare these values with European populations. The sample was composed of 1356 Brazilian schoolchildren of both genders (660 males, 696 females), aged 6 to 11 years, divided into white (840) and black (516) groups and compared to age- and gender-matched Europeans. AD-SoS of the schoolchildren increased significantly with age for both genders. Significantly higher AD-SoS values were observed for the white children (1916 ± 58) compared to their black counterparts (1898 ± 72) and for the female gender (1920 ± 61) compared to the male gender (1898 ± 66). Overall, the AD-SoS outcomes for females were similar to those of European studies. However, the AD-SoS of the Brazilian schoolchildren of both genders and skin colors was lower than that reported for children in Poland. AD-SoS outcomes for Brazilian schoolboys were similar to those obtained in Italian studies and were lower than those of the Spanish children. In conclusion, Brazilian schoolchildren of both genders and skin colors showed lower bone quantities than Polish children and Spanish males, and levels similar to Italian children and Spanish females.

Comparison of bone quantity by ultrasound measurements of phalanges between white and black children living in Paraná, Brazil, with Europeans.

The objective of this study was to determine bone quantity by ultrasound measurements of the proximal finger phalanges (AD-SoS = amplitude-dependent speed of sound) of healthy Brazilian schoolchildren living in Paraná, Brazil and to compare these values with European populations. The sample was composed of 1356 Brazilian schoolchildren of both genders (660 males, 696 females), aged 6 to 11 years, divided into white (840) and black (516) groups and compared to age- and gender-matched Europeans. AD-SoS of the schoolchildren increased significantly with age for both genders. Significantly higher AD-SoS values were observed for the white children (1916 ± 58) compared to their black counterparts (1898 ± 72) and for the female gender (1920 ± 61) compared to the male gender (1898 ± 66). Overall, the AD-SoS outcomes for females were similar to those of European studies. However, the AD-SoS of the Brazilian schoolchildren of both genders and skin colors was lower than that reported for children in Poland. AD-SoS outcomes for Brazilian schoolboys were similar to those obtained in Italian studies and were lower than those of the Spanish children. In conclusion, Brazilian schoolchildren of both genders and skin colors showed lower bone quantities than Polish children and Spanish males, and levels similar to Italian children and Spanish females.

Complete XY gonadal dysgenesis due to p.D293N homozygous mutation in the NR5A1 gene: a case study.

The SRY gene (sex-determining region on the Y chromosome; MIM *480000) is responsible for initiating male gonadal development. However, only 15-20% of the cases of XY gonadal dysgenesis are due to mutations in its sequence. Recently, heterozygous mutations in the NR5A1 gene (nuclear receptor subfamily 5, group A, member 1; MIM +184757) have been described in association with ovarian failure and disorders of testis development with or without adrenal failure. Here we describe a case of XY complete gonadal dysgenesis due to a p.D293N homozygous mutation in the NR5A1 gene, with normal SRY and no adrenal failure.

A novel homozygous splice acceptor site mutation of KISS1R in two siblings with normosmic isolated hypogonadotropic hypogonadism.

CONTEXT: Loss-of-function mutations of the kisspeptin-1 receptor gene, KISS1R, have been identified in patients with normosmic isolated hypogonadotropic hypogonadism (nIHH). OBJECTIVE: To investigate KISS1R defects in patients with absent or delayed puberty. PATIENTS: We investigated KISS1R gene defects in a cohort of 99 Brazilian patients with nIHH or constitutional delay of puberty (CDP). METHODS: The entire coding region of KISS1R was amplified by PCR followed by automatic sequencing. In addition, screening for KISS1R exonic deletions was performed by multiplex ligation-dependent probe amplification. RESULTS: One novel homozygous KISS1R mutation was identified in two siblings with nIHH. This variant was an insertion/deletion (indel) mutation characterized by the deletion of three nucleotides (GCA) at position -2 to -4, and by the insertion of seven nucleotides (ACCGGCT) at the same position, within the 3' splice acceptor site of intron 2 of KISS1R. The brothers who carried this KISS1R mutation had no clinical evidence of pubertal development at the ages of 14 and 20 years. Computational analysis of this indel mutation predicted the generation of an abnormal protein. In addition, a new heterozygous KISS1R variant (p.E252Q) was identified in a male patient with sporadic nIHH. However, in vitro studies of this variant did not demonstrate functional impairment. Only known polymorphisms were identified in patients with CDP. CONCLUSION: Loss-of-function mutations of KISS1R represents a rare cause of nIHH, and was absent in patients with CDP. We have described a novel KISS1R homozygous splice acceptor site mutation in the familial form of nIHH.

Influence of gender on the EMG signal of the quadriceps femoris muscles and performance in high-intensity short-term exercise.

The aim of this study was to investigate the influence of gender on the EMG signal of the muscles of the quadriceps femoris and the physical performance in high-intensity, short-term exercise. Fourteen volunteers (7 men = 29.1 +/- 2.8 years and 7 women = 22.6 +/- 2.9 years) performed a Wingate Test (WT) with a load of 7.5% of body mass. The variables analyzed during the WT were the Relative Peak Power (W.Kg(-1)) (RPP), Relative Mean Power (W.Kg(-1)) (RMP), Fatigue Index (%) (FI) and Peak Power Instant (s) (PPI). EMG signals of the superficial muscles of the quadriceps femoris (QF) from the right leg: rectus femoris (RF), vastus lateralis (VL) and vastus medialis (VM) were analyzed through root mean square (RMS) values and the normalized median frequency (MNF) determined using the Fast Fourier Transform (FFT). The RPP and the RMP were significantly higher in men when compared to women (9.99 +/- 0.96 vs. 7.66 +/- 1.00 W.kg(-1); 7.23 +/- 0.49 vs. 5.65 +/- 0.61 W.kg(1), P < 0.05; respectively). No significant difference between genders was found on RMS and NMF during WT (P > 0.05). Although RPP and RMP were influenced by gender, the RMS and the NMF of the superficial muscles of the QF did not show the same behavior, suggesting that other mechanisms, not related to motor unit recruitment and speed of nervous stimuli in the muscle fiber may be associated to the lower performance of women in high-intensity, short-term exercise.

Complement 4 phenotypes and genotypes in Brazilian patients with classical 21-hydroxylase deficiency.

The aim of this work was to analyse C4 genotypes, C4 protein levels, phenotypes and genotypes in patients with the classical form of 21-hydroxylase deficiency. Fifty-four patients from 46 families (36 female, 18 male; mean age 10.8 years) with different clinical manifestations (31 salt-wasting; 23 simple-virilizing) were studied. Taq I Southern blotting was used to perform molecular analysis of the C4/CYP21 gene cluster and the genotypes were defined according to gene organization within RCCX modules. Serum C4 isotypes were assayed by enzyme-linked immunosorbent assay. The results revealed 12 different haplotypes of the C4/CYP21 gene cluster. Total functional activity of the classical pathway (CH50) was reduced in individuals carrying different genotypes because of low C4 concentrations (43% of all patients) to complete or partial C4 allotype deficiency. Thirteen of 54 patients presented recurrent infections affecting the respiratory and/or the urinary tracts, none of them with severe infections. Low C4A or C4B correlated well with RCCX mono-modular gene organization, but no association between C4 haplotypes and recurrent infections or autoimmunity was observed. Considering this redundant gene cluster, C4 seems to be a well-protected gene segment along the evolutionary process.

Congenital perineal lipoma presenting as ambiguous genitalia.

BACKGROUND: Congenital perineal lipoma is extremely rare and may lead to a misdiagnosis of ambiguous genitalia. CASE REPORTS: We report on two girls referred to our service for ambiguous genitalia. Patient 1 (17 days old) and patient 2 (2 months old) had unremarkable gestational and perinatal histories. Both had normal female external genitalia and a 46,XX karyotype. Patient 1 had a polypoid, protruding 3.0 x 2.0 x 1.5-cm phallic-like mass arising at the inferior border of the left labium majora, and patient 2 had a similar mass of 1.5 x 1.5 x 1.0 cm at the same site and an imperforate anus. In both cases the mass was removed and found to be a lipoma. DISCUSSION: To our knowledge, perineal lipoma has been reported only in eleven girls, nine of them with associated anorectal malformation. Migration and fusion of the labioscrotal folds and formation of the urorectal septum are simultaneous developmental events occurring in the same region, which may explain the association of perineal lipoma and anorectal malformations.

Inhibition of CYP21A2 enzyme activity caused by novel missense mutations identified in Brazilian and Scandinavian patients.

BACKGROUND: Most patients with 21-hydroxylase deficiency carry CYP21A1P-derived mutations, but an increasing number of novel and rare mutations have been reported in disease-causing alleles. OBJECTIVE: Functional effects of three novel (p.G56R, p.L107R, p.L142P) and one recurrent (p.R408C) CYP21A2 mutations were investigated. The degree of enzyme impairment caused by p.H62L alone or combined to p.P453S was also analyzed. DESIGN: The study included 10 Brazilian and two Scandinavian patients. To determine the deleterious role of each mutant protein, in vitro assays were performed in transiently transfected COS-1 cells. For a correct genotype-phenotype correlation, the enzymatic activities were evaluated toward the two natural substrates, 17-hydroxyprogesterone and progesterone. RESULTS: Low levels of residual activities obtained for p.G56R, p.L107R, p.L142P, and p.R408C mutants classified them as classical congenital adrenal hyperplasia mutations, whereas the p.H62L showed an activity within the range of nonclassical mutations. Apparent kinetic constants for p.H62L confirmed the nonclassical classification as the substrate binding capacity was within the same magnitude for mutant and normal enzymes. A synergistic effect was observed for the allele bearing the p.H62L+p.P453S combination because it caused a significant reduction in the enzymatic activity. CONCLUSIONS: We describe the functional analysis of five rare missense mutations identified in Brazilian and Scandinavian patients. The p.G56R, p.L107R, and p.L142P are reported for the first time. Most probably these novel mutations are closer to null than the p.I172N, but for the p.G56R, that might not be the case, and the p.H62L is definitely a nonclassical mutation.

Bone density gain at proximal phalanges in healthy males aged 18-25 years after 16 weeks of upper-arm muscle weight training.

AIM: The aim of this study was to determine the effect of an upper-arm muscle weight training (WT) protocol over 16 weeks on bone density at the proximal phalanges in young healthy men. METHODS: Fifty-one healthy volunteer men were selected, 16 for an experimental group and 35 for a control group. The experimental group was submitted to the prescribed WT protocol to develop the strength of upper arm muscles, during 16 weeks, at a frequency of 3 times per week for approximately 60 min per session. Anthropometric data (weight, height, body mass index, corrected mid upper-arm circumference [cMUAC], and percentage of upper-arm muscle mass [%UAMM]) and bone density by quantitative ultrasound (DBM Sonic BP, IGEA, Italy) at proximal phalanges (amplitude dependent speed of sound [AD-SoS], T-score, %T-score) were evaluated on non-dominant limb before the beginning of the study (T0) and after 16 weeks (T1). RESULTS: There were no significant differences among all variables at T0 and T1 in the control group, nor at T0 between both groups. In the experimental group, cMUAC, %UAMM, AD-SoS, T-score and %T-score were significantly higher at T1 in relation to T0, as well as between T1 of the experimental group and T1 of the control group (all with P<0.0001). The gain of %T-score showed a correlation between cMUAC gain (P=0.005) and %UAMM gain (P=0.002). The experimental group showed 7% of bone mass gain. CONCLUSION: These data suggested that a WT protocol to develop strength of upper arm muscles over 16 weeks was effective for increasing bone density at the proximal phalanges in healthy young men.

The influence of parental origin of X chromosome genes on the stature of patients with 45 X Turner syndrome.

Thirty-seven 45 X Turner syndrome patients with confirmed peripheral blood lymphocyte karyotype were initially selected to determine the origin of the retained X chromosome and to correlate it with their parents' stature. Blood samples were available in 25 families. The parental origin of the X chromosome was determined in 24 informative families through the analysis of the exon 1-CAG repeat variation of the androgen receptor gene. In 70.8% of the cases, the retained X chromosome was maternal in origin and 29.2% was paternal. When we classified the patients according to maternal (Xm) or paternal (Xp) X chromosome, there was a positive correlation between patients' and maternal heights only in the Xm group. There was no correlation with paternal height in either group, and a significant correlation with target height was only observed in the Xm group. In conclusion, maternal height is the best variable correlating with the height of 45 X Turner syndrome patients who retain the maternal X chromosome, suggesting a strong influence of genes located on the maternal X chromosome on stature.