Glycated hemoglobin and sleep apnea syndrome in children: beyond the apnea-hypopnea index.

PURPOSE: Snoring and obstructive sleep apnea syndrome (OSA) are frequent conditions in pediatrics. Glycated hemoglobin (HbA1C) is a useful homeostatic biomarker of glycemia and may reflect alterations deriving from sleep breathing disorders. The aim of this study was to relate the severity of OSA with blood HbA1C levels in children. METHODS: A descriptive observational study in snoring patients was performed. All patients underwent a sleep study and classified either as simple snorers (apnea-hypopnea index; AHI ≤ 1 episodies/h) or as OSA patients (AHI > 1 episodes/h). In the following morning, a blood glycemic profile (fasting glucose, insulin, HbA1C, and the HOMA index) was performed to every individual. RESULTS: A total of 48 patients were included. HbA1C levels were shown to be increased in the moderate OSA (AHI > 5 episodes/h) group (5.05 ± 0.25 vs. 5.24 ± 0.29%; p = 0.019). Significant correlations were found between HbA1C values and AHI (r = 0.345; p = 0.016) and also with oxygen desaturation index (r = 0.40; p = 0.005). Correlations remained significant after adjusting by age and body mass index. The AHI-associated change in HbA1C was 13.4% (p = 0.011). CONCLUSIONS: In the pediatric population, HbA1C is a biomarker associated with OSA severity, and this relationship is age- and obesity-independent. The fact that this association was observed in snoring patients could help the physician in the distinction between those patients affected with OSA and those with simple snoring. Therefore, HbA1C measurement could play a major role in the diagnosis and the management of the syndrome.

Clinical and molecular evaluation of SHOX/PAR1 duplications in Leri-Weill dyschondrosteosis (LWD) and idiopathic short stature (ISS).

CONTEXT: Léri-Weill dyschondrosteosis (LWD) is a skeletal dysplasia characterized by disproportionate short stature and the Madelung deformity of the forearm. SHOX mutations and pseudoautosomal region 1 deletions encompassing SHOX or its enhancers have been identified in approximately 60% of LWD and approximately 15% of idiopathic short stature (ISS) individuals. Recently SHOX duplications have been described in LWD/ISS but also in individuals with other clinical manifestations, thus questioning their pathogenicity. OBJECTIVE: The objective of the study was to investigate the pathogenicity of SHOX duplications in LWD and ISS. DESIGN AND METHODS: Multiplex ligation-dependent probe amplification is routinely used in our unit to analyze for SHOX/pseudoautosomal region 1 copy number changes in LWD/ISS referrals. Quantitative PCR, microsatellite marker, and fluorescence in situ hybridization analysis were undertaken to confirm all identified duplications. RESULTS: During the routine analysis of 122 LWD and 613 ISS referrals, a total of four complete and 10 partial SHOX duplications or multiple copy number (n > 3) as well as one duplication of the SHOX 5' flanking region were identified in nine LWD and six ISS cases. Partial SHOX duplications appeared to have a more deleterious effect on skeletal dysplasia and height gain than complete SHOX duplications. Importantly, no increase in SHOX copy number was identified in 340 individuals with normal stature or 104 overgrowth referrals. CONCLUSION: MLPA analysis of SHOX/PAR1 led to the identification of partial and complete SHOX duplications or multiple copies associated with LWD or ISS, suggesting that they may represent an additional class of mutations implicated in the molecular etiology of these clinical entities.

The first clinical case of a mutation at residue K185 of Kir6.2 (KCNJ11): a major ATP-binding residue.

BACKGROUND: Closure of the adenosine triphosphate (ATP)-sensitive potassium (K(ATP)) channel plays a key role in insulin secretion from the pancreatic beta-cells. Many mutations in KCNJ11 and ABCC8, which respectively encode the pore-forming (Kir6.2) and regulatory (SUR1) subunits of the K(ATP) channel, cause neonatal diabetes. All such mutations impair the ability of metabolically generated ATP to close the channel. Although lysine 185 is predicted to be a major contributor to the ATP-binding site of Kir6.2, no mutations at this residue have been found to cause neonatal diabetes to date. METHODS: We report a 3-year-old girl with permanent neonatal diabetes (PNDM) caused by a novel heterozygous mutation (K185Q) at residue K185 of KCNJ11. The patient presented with marked hyperglycaemia and ketoacidosis at 70 days after birth, and insulin therapy was commenced. RESULTS: Wild-type and mutant K(ATP) channels were expressed in Xenopus oocytes and the effects of intracellular ATP on macroscopic K(ATP) currents in inside-out membrane patches were measured. In the simulated heterozygous state, the K185Q mutation caused a substantial reduction in the ability of MgATP to inhibit the channel. Heterozygous K185Q channels were still blocked effectively by the sulphonylurea tolbutamide. CONCLUSIONS: We report the first clinical case of a PNDM caused by a mutation at K185. Functional studies indicate that the K185Q mutation causes PNDM by reducing the ATP sensitivity of the K(ATP) channel, probably via a reduction in ATP binding to Kir6.2. Based on the experimental data, the patient was successfully transferred to sulphonylurea therapy.

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.

Pheochromocytoma and clear-cell renal carcinoma in a child with von Hippel-Lindau disease: a patient report.

A 6 year-old boy with von Hippel-Lindau (VHL) disease presented with hypertension due to bilateral pheochromocytomas. At age 13 he developed a renal carcinoma and bilateral paragangliomas. His mother had retinal angiomas, bilateral pheochromocytomas and a cerebellar hemangioblastoma. This unusual presentation illustrates the complexity and difficulties associated with the management of VHL disease.