Prevalence of insulin resistance and impaired glucose tolerance in a sample of obese Spanish children and adolescents

The prevalence of obesity in children has increased in developed countries in the last decades. It is associated with alterations in glucose metabolism that may be present in childhood. To assess the frequency of glucose metabolism alterations and insulin resistance and their possible determinants in a sample of obese children from Valladolid (Spain), we retrospectively studied 100 obese children and adolescents (11.59 ± 2.73 years). Anthropometric measures, biochemical parameters, and oral glucose tolerance test (OGTT) were performed. Insulin resistance was evaluated with fasting insulin, HOMA index, and insulin values in OGTT. Impaired glucose tolerance was found in 15% of the sample, and was the most frequent of glucose metabolism alterations. Impaired fasting glucose was found in 2%. No case of type 2 diabetes was found. Acanthosis nigricans was present in 22%, with predominance in females, but not all presented insulin resistance. The prevalence of insulin resistance was 29% when HOMA index was used, and 50% when the insulin response in OGTT was used. Not all patients with impaired glucose tolerance had a pathological HOMA index, and not all with pathological HOMA index presented insulin resistance when insulin values in OGTT were used. Higher 2-h post-OGTT insulin levels were found in children with impaired glucose tolerance. It is paramount to identify young people with glucose regulation alterations for early, intensive intervention to prevent or at least postpone the onset of type 2 diabetes. OGTT is a screening tool necessary to fulfill this objective.

Klinefelter syndrome and short stature: an unusual combination

Klinefelter syndrome is not easy to diagnose in childhood because of the absence of significant manifestations before puberty. Three main clinical signs should suggest the diagnosis in a child: small testes, tall stature, and mental retardation or learning problems. We present a patient with Klinefelter syndrome and short stature due to growth hormone deficiency. His height was below the third percentile for age and his bone age delayed. Maximal serum GH levels after insulin-induced hypoglycemia and clonidine were low, demonstrating GH deficiency. He received growth hormone treatment with good response. The diagnosis of Klinefelter syndrome was made at puberty, because the patient did not present a normal progression of testicular development and puberty. At that moment, a karyotype was made confirming the suspected diagnosis. We wish to emphasize the rare association between Klinefelter syndrome and growth hormone deficiency.

Novel (60%) and recurrent (40%) androgen receptor gene mutations in a series of 59 patients with a 46,XY disorder of sex development

BACKGROUND

Androgen receptor (AR) gene mutations are the most frequent cause of 46,XY disorders of sex development (DSD) and are associated with a variety of phenotypes, ranging from phenotypic women [complete androgen insensitivity syndrome (CAIS)] to milder degrees of undervirilization (partial form or PAIS) or men with only infertility (mild form or MAIS).

OBJECTIVE

The aim of the study was to characterize the contribution of the AR gene to the molecular cause of 46,XY DSD in a series of Spanish patients.

SETTING

We studied a series of 133 index patients with 46,XY DSD in whom gonads were differentiated as testes, with phenotypes including varying degrees of undervirilization, and in whom the AR gene was the first candidate for a molecular analysis.

METHODS

The AR gene was sequenced (exons 1 to 8 with intronic flanking regions) in all patients and in family members of 61% of AR-mutated gene patients.

RESULTS

AR gene mutations were found in 59 individuals (44.4% of index patients), of whom 46 (78%) were CAIS and 13 (22%) PAIS. Fifty-seven different mutations were found: 21.0% located in exon 1, 15.8% in exons 2 and 3, 57.9% in exons 4-8, and 5.3% intronic. Twenty-three mutations (40.4%) had been previously described and 34 (59.6%) were novel.

CONCLUSIONS

AR gene mutation is the most frequent cause of 46,XY DSD, with a clearly higher frequency in the complete phenotype. Mutations spread along the whole coding sequence, including exon 1. This series shows that 60% of mutations detected during the period 2002-2009 were novel.