Molecular defects of the CYP21 gene in Spanish girls with isolated precocious pubarche.

OBJECTIVE: To determine the frequency of mutant alleles in the CYP21 gene in Spanish girls presenting with precocious pubarche (PP) and to assess the relationships between genotype and endocrine-metabolic variables. DESIGN: Fifty-three unrelated girls with a history of PP (14 prepubertal, 8 pubertal and 31 postmenarcheal) and 35 controls were studied. METHODS: Genomic DNA was extracted from peripheral blood leukocytes. After selection against the pseudogen, an allele-specific PCR was used to identify 14 known mutations in the CYP21 gene. The mutations studied were Pro30Leu, splice intron 2, Ilel72Asn, Cluster E(6), Glyl92Ser, Ins T, GT-CT, Gln318-stop, Arg357Trp, Trp406-stop, Pro453Ser, Arg483Pro, Arg483 frameshift and Val281Leu. A standard 2-h oral glucose tolerance test was performed in all PP girls. Ovarian 17-hydroxyprogesterone (17-OHP) responses to gonadotrophin-releasing hormone-agonist stimulation was assessed in postmenarcheal PP girls. RESULTS: Thirteen PP girls and eight control girls were heterozygous for one of the mutations studied. The frequency of the carrier status was 25% and 23% in the PP and control groups respectively. Severe mutations were found in 33% of the carrier girls. Serum 17-OHP responses to ACTH stimulation were similar in carriers and non-carriers (351+/-65 vs 334+/-22 ng/dl). The presence of ovarian hyperandrogenism and/or hyperinsulinism was also not related to the carrier status. CONCLUSION: The incidence of molecular defects in the CYP21 gene in the present study was comparable in the PP and control groups. We found no relationship between the presence of carrier status and endocrine-metabolic abnormalities. Prospective studies of larger cohorts of PP girls are needed to ascertain the long-term clinical relevance of CYP21 heterozygosity.

Hyperinsulinemia in pre- and post-pubertal children born small for gestational age.

BACKGROUND: Reduced fetal growth is a potential risk factor for development of metabolic abnormalities in later life. The relationship between low birthweight and impaired glucose tolerance, type 2 diabetes and insulin resistance in adulthood has been well documented. PURPOSE: Assuming that fetal undernutrition is associated with insulin resistance in middle age, we elected to study whether this process may already be present in young adults and adolescents born small for gestational age (SGA). SUBJECTS AND METHODS: Children born in Vall d'Hebron Hospital Infantil, Barcelona, between 1986 and 1989 and between 1978 and 1983 with birthweights below the third centile for the local standard values, were invited to participate in the present study. Of those, 51 (22 girls and 29 boys) were pre-pubertal with 9.4 +/- 0.2 years of age and 49 (29 girls and 20 boys ) were post-pubertal, with 17.3 +/- 0.3 years of age. All patients underwent a standard, 2-hour oral glucose tolerance test. Insulin and glucose responses were compared with our previously published data in control children with normal birthweight. RESULTS: The insulin response at 30 min after glucose load was significantly higher (p < 0.001) in pre- and post-pubertal girls and boys formerly SGA than in controls. In addition, the girls also had a higher insulin response at 60 and 120 min. Mean serum insulin (MSI), the area under the insulin curve during the glucose challenge, was statistically increased in pre- and post-pubertal boys and girls born SGA when compared to controls. CONCLUSION: The presence of high insulin levels after an oral glucose challenge in children and adolescents born SGA might be considered as an early marker of subsequent insulin resistance in adulthood. Furthermore, our population offers the opportunity to study the natural course of hyperinsulinemia and its outcome. Follow-up of this cohort may be helpful in distinguishing a subset of young children and adolescents in whom therapeutic intervention could be done.

Identification of three novel mutations in the insulin receptor gene in type A insulin resistant patients.

Type A insulin resistance syndrome is characterized by the association of ovarian hyperandrogenism, acanthosis nigricans, and severe insulin resistance. We have identified three novel mutant alleles of the insulin receptor gene in 3 patients with type A syndrome, a severe form of insulin resistance. Two of the patients were sisters (A1, A2), 1 of them was a compound heterozygote for a mutation at the 3'-splice acceptor site of intron 21 (AG-->AA), and a missense mutation Val140Leu in exon 2. Her sister was a simple heterozygote for the 3'-splice acceptor mutation. The third patient (A3) was heterozygous for the missense mutation Ala1028Val in exon 17, in the consensus sequence for ATP binding.

Pronounced adrenarche and precocious pubarche in boys.

In girls, pronounced adrenarche with precocious pubarche (PP) has been related to reduced fetal growth and to a cluster of endocrine-metabolic abnormalities. We examined whether these associations are also evident in boys with PP. The study population consisted of matched groups of boys (n = 58; age range 5-15 years) without or with a history of PP. After stratification for pubertal development, non-PP and PP boys displayed comparable results for the studied variables, including serum insulin-like growth factor I, sex hormone binding globulin, insulin-like growth factor binding proteins 1 and 3, indices of circulating glucose and insulin responsiveness to an oral glucose load, and birth weight SD score. In conclusion, the present results indicate that adrenarche-driven PP in boys is, in contrast to PP in girls, not associated with a cluster of endocrine-metabolic abnormalities and is not related to reduced fetal growth. These observations support the view that adrenarche-driven PP in boys may be regarded as a variant of normal development. Copyrightz1999S.KargerAG,Basel

Leptin values in placental cord blood of human newborns with normal intrauterine growth after 30-42 weeks of gestation.

OBJECTIVE: To evaluate leptin values in placental cord blood of newborns with normal intrauterine growth after 30-42 weeks of gestation. DESIGN: Leptin, a protein encoded by the ob gene, plays an important role in the regulation of feeding behaviour and energy balance in rodents, primates and humans. The presence of leptin in human amniotic fluid and cord blood has recently been reported in human gestations at term and the possible role of leptin in human fetal growth suggested. However, little is known of leptin synthesis during human foetal development. Thus, the aim of our work was to measure leptin (RIA, Linco Research, Inc.) in placental cord blood of human newborns at different fetal ages. PATIENTS: One hundred and twenty-six healthy newborns with normal intrauterine growth were studied. Twenty-nine were preterm (15 males and 14 females; gestational age: 30-36 weeks) and 99 were at term (49 males and 48 females; gestational age: 37-42 weeks). RESULTS: Leptin values increase progressively throughout gestation from 1.30 +/- 0.53 ng/ml at 30 weeks of gestation to 7.98 +/- 4.96 ng/ml (mean +/- SD) at term, and correlate positively with birth weight (r = 0.56, p < 0. 005, n = 126), length (r = 0.37, p < 0.005, n = 126), BMI (r = 0.57, p < 0.005, n = 126), head circumference (r = 0.37, p < 0.005, n = 126), gestational age (r = 0.48, p < 0.005, n = 126) and placental weight (r = 0.38, p < 0.003, n = 59). Leptin values are statistically significantly lower (p < 0.005) preterm (median: 2.05 ng/ml; range: 0.7-8.3 ng/ml) than at term (median: 7.0 ng/ml; range: 1.1-28.1 ng/ml). Leptin values are also significantly (p < 0.005) higher in females (median: 7.2 ng/ml; range: 0.9-23.6 ng/ml, n = 62) than in males (median: 4.8 ng/ml; range: 0.7-28.1 ng/ml, n = 64), although there are no differences in weight (2,864 +/- 536 g in females vs. 2,937 +/- 744 g in males). Multiple regression analysis shows weight to be a positive sex-independent predictor of serum leptin values (p < 0.0005). Sex also proves to be a predictor of leptin, independently of weight and is higher in females than in males (p < 0.003). CONCLUSION: Leptin is present in placental human cord blood after 30-42 weeks of gestation. Newborn weight and sex are independent predictors of leptin values.

Hyperinsulinemia and decreased insulin-like growth factor-binding protein-1 are common features in prepubertal and pubertal girls with a history of premature pubarche.

The fasting insulin resistance index, mean blood glucose, mean serum insulin (MSI), early insulin response to glucose, glucose uptake rate in peripheral tissues, and insulin sensitivity indexes in response to a standard oral glucose tolerance test; serum insulin-like growth factor I (IGF-I), IGF-binding protein-1 (IGFBP-1), IGFBP-3, and sex hormone binding-globulin (SHBG) levels; and the free androgen indexes were evaluated in 98 girls with premature pubarche [PP; prepubertal (B1; n = 32), early pubertal (B2; n = 27), midpubertal (B3; n = 23), and postmenarcheal (B5; n = 16)] and in 86 Tanner stage- and bone age-matched controls. We ascertained whether hyperinsulinemia is already present in PP girls before or during pubertal development and whether these patients show a similar pattern of growth factor secretion as normal girls. Body mass indexes did not differ significantly between patients and controls within the same pubertal stage. MSI levels showed a significant increase with pubertal onset in all subjects, as expected. Patients showed significantly higher MSI values than controls at all Tanner stages (P < 0.03, P = 0.03, P = 0.03, and P < 0.05 for B1, B2, B3, and B5, respectively); higher insulin response to glucose at B1, B2, and B3 (P < 0.03, P = 0.03, and P < 0.05, respectively); higher glucose uptake rate in peripheral tissues at B1 and B2 (P < 0.04 and P = 0.02, respectively); and a later rise in insulin sensitivity compared to controls. PP girls also showed lower IGFBP-1 levels at B1 and B5 (P < 0.01 and P = 0.02, respectively), lower SHBG concentrations at B5 (P < 0.0005), and higher free androgen indexes at B1, B3, and B5 (P < 0.01, P < 0.05, and P < 0.001, respectively) compared to controls. Among others, significant correlations between SHBG and MSI levels (r = -0.49; P < 0.0001) and between SHBG and IGFBP-1 levels (r = 0.41; P < 0.0001) were found in all subjects. Hyperinsulinemia, increased early insulin responses to glucose, increased glucose uptake rate in peripheral tissues, elevated free androgen indexes, and decreased SHBG and IGFBP-1 levels are present in most girls with PP from childhood. These findings lend strong support to the concept that PP is not a benign condition, and long term follow-up of these patients into adulthood is recommended. The possible causal role of hyperinsulinemia in adrenal and/or ovarian androgen hypersecretion remains to be established.

Pubertal changes in insulin secretion and peripheral insulin sensitivity.

Using a simple and standardized method we estimated both insulin secretion and insulin sensitivity in peripheral tissues in relation to Tanner pubertal stages. Early insulin response, mean blood glucose (MBG), mean serum insulin (MSI), glucose uptake rate in peripheral tissues and insulin sensitivity index (SI) in response to the standard oral glucose tolerance test were evaluated in 73 normal girls. Study subjects were divided into 4 groups: group 1 (Tanner stage I, n = 20); group 2 (Tanner stage II, n = 14); group 3 (Tanner stages III and IV, n = 15), and group 4 (Tanner stage V, n = 24). Steroid levels and insulin-like growth factors were determined to characterize clinical pubertal development. MBG was similar in all groups but MSI increased at stage II and retained similar values throughout puberty, with those of group I being statistically lower than in the other groups (p < 0.001). When MSI values were adjusted per kilogram of body weight, a significant increase was observed in group II (p < 0.05). The MSI adjusted values were: group 1, 1.0 +/- 0.4; group 2, 1.4 +/- 0.4; group 3, 1.0 +/- 0.3, and group 4, 1.0 +/- 0.4 mU/l/kg. SI values were similar in groups 1 and 2 and significantly lower than in groups 3 and 4 (p < 0.001). Our results confirm both that insulin secretion is related to age and that an insulin-resistant state occurs during puberty. Thus, the insulin-resistant state coincides with Tanner stage II. In conclusion, this mathematical approach is considered to be a simple and reliable method for analyzing the possible alterations in insulin secretion and action in children and adolescents in whom more sophisticated procedures must be limited in this early period of life for ethical reasons.