Visfatin and its genetic variants are associated with obesity-related morbidities and cardiometabolic risk in severely obese children.

BACKGROUND: Visfatin is an adipokine, associated with obesity and possibly glucose regulation. OBJECTIVE: The aim of this study was to examine the association of visfatin and its genetic variants with adiposity, cardiometabolic risk factors and obesity-related morbidities in obese children. METHODS: Anthropometric measurements, dual energy X-ray absorptiometry scan, fasting blood samples and oral glucose tolerance tests were performed for 243 obese children. We screened the visfatin gene of 24 obese subjects and then performed genotyping of identified genetic variants in other 219 obese children through direct DNA sequencing. RESULTS: Fasting serum visfatin correlated with measures of obesity and liver enzymes and was elevated in obese children with abnormal glucose tolerance and non-alcoholic fatty liver disease. The two upstream single nucleotide polymorphisms, -3187G>A (rs11977021) and -1537C>T (rs61330082), were at complete linkage disequilibrium. The AA genotype of -3187G>A was associated with higher serum visfatin (6.17 ± 0.76 ng mL(-1) vs. 3.92 ± 0.44 ng mL(-1)) and higher triglyceride (1.39 ± 0.08 mmol L(-1) vs. 1.19 ± 0.07 mmol L(-1)) as compared with the GG genotype. There was also a significant linear increase in serum visfatin across GG to GA to AA genotype of -3187G>A, indicating possible additive effect of A allele. The dominant GA + AA genotype model of +21426G>A (rs2302559) was associated with lower serum visfatin (3.83 ± 0.56 ng mL(-1) vs. 5.13 ± 0.34 ng mL(-1)) and lower plasma glucose (4.37 ± 0.08 mmol L(-1) vs. 4.77 ± 0.12 mmol L(-1)) as compared with the GG genotype. CONCLUSION: Visfatin and its genetic variants were associated with adiposity, obesity-related morbidities and adverse cardiometabolic parameters. This supported our hypothesis that visfatin plays a significant role in the development of obesity-related morbidities and cardiometabolic risk.

Gonadal mosaicism 45,X/46,X,psu dic(Y)(q11.2) resulting in a Turner phenotype with mixed gonadal dysgenesis.

A two-year-and-eight-month-old girl presented with clitoromegaly and short stature. Two cell lines, 45,X and 46,X,idic(Y)(q11.2), were observed. Cytogenetic and fluorescence in situ hybridisation investigations were carried out on her peripheral lymphocytes and gonadal cells, to determine the genotype-phenotype effect with respect to differential tissue distribution, effects of the sex determining region of the Y chromosome, and the break-points in the azoospermia factor region.

Isolated haploinsufficiency of exon 1 of the SHOX gene in a patient with idiopathic short stature.

This paper reports the case of a 16-year-old woman with idiopathic short stature (ISS) who was detected to be haploinsufficient in only exon 1 of the short stature homeobox-containing (SHOX) gene by RQ-PCR and had two copies of the other six exons intact. The translation of the SHOX protein and of the SHOX promoter may be potentially affected if the deletion of exon 1 is extended further upstream. Further studies may help in determining the significance of partial exonic deletions of the SHOX gene in relation to ISS.

The perils of puberty.

Puberty and adolescence represent a transitional phase from childhood to adulthood, and are defined by the attainment of secondary sexual characteristics and reproductive capability, occurring concomitantly with psychological and social development. The perils of puberty lie in the difficult and complex inter-relationship of biological, psychological and social changes, as the adolescent strives to adjust to new social roles and identities, and new reproductive capacities. An appreciation of these changes in normal puberty is essential to all professionals caring for adolescents.

Tyrosine phosphatase-like protein (IA-2) and glutamic acid decarboxylase (GAD65) autoantibodies: a study of Chinese patients with diabetes mellitus.

Type 1 diabetes in most Asian populations may not have a salient autoimmune basis when assessed with single determinations of the major markers, islet cell antibodies (ICAs) and glutamic acid decarboxylase antibodies (GAD65ab). With the inclusion of antibodies to tyrosine phosphatase-like protein IA-2 (IA-2ab) as an additional major marker, we re-examined autoimmune diabetes in a group of Chinese patients. We studied 272 subjects at various stages of disease with blood samples procured for biochemical analysis. ICAs were measured by immunofluorescence, GAD65ab and IA-2ab by radioimmunoassay. Sixty-seven patients fulfilled clinical diagnosis of type 1 diabetes and the remaining 205 patients were type 2. Prevalence of single autoantibody type in recent-onset type 1 diabetes ( < 1 year duration; n = 47) showed 10.6% with ICAs, 44.7% GAD65ab and 36.2% IA-2ab. GAD65ab account for more than two-thirds of the markers found in type 1 diabetes. Combined analysis further showed that 51.1% had at least one antibody type, 31.9% with two or more antibodies and 8.5% with all three antibodies. Islet autoimmunity presence in childhood-onset type 1 diabetes improved with the addition of IA-2ab, though less impact was seen in the adult-onset. Similarly, combined analysis for type 2 patients with recent diabetes showed a modest increase to 13% with islet autoimmunity compared to 8% when assessed by GAD65ab alone. Combining IA-2ab and GAD65ab assays results detected slightly more immune-mediated diabetes, compared to using a single GAD65ab determination. Non-autoimmune causes need to be considered in the pathogenesis of type 1 diabetes in Chinese, particularly in adults.

Maternal thyrotoxicosis causing central hypothyroidism in infants.

We describe three infants born to mothers with poorly controlled Graves' disease, who developed transient central hypothyroidism in the immediate postnatal period. Suppression of the fetal pituitary-thyroid axis may be due to placental transfer of thyroxine from the hyperthyroid mother. This may persist for months postnatally, necessitating treatment to optimise neurodevelopmental outcome.

Epidemiology of 21-hydroxylase deficiency in Singapore.

We report the incidence and epidemiology of 21-hydroxylase deficiency in Singapore, based on a retrospective study of all known patients diagnosed with classical 21-hydroxylase deficiency in the past 21 years. The database was obtained from the case registry and questionnaire methodology, with 100% coverage of all practising pediatricians in Singapore. There were 42 patients affected with 21-hydroxylase deficiency in 964,558 live births over 21 years, comprising 64.3% salt wasters and 35.7% simple virilizers, of whom 50.0% were males and 50.0% females. The incidence of classical 21-hydroxylase deficiency is 4.5 per 100,000 live births, with a carrier frequency of 1:76, and a gene frequency of 0.0067. Although retrospective studies have inherent limitations, the gender and phenotype ratios suggest that the data provide a crude incidence level. This study underscores the necessity for prospective neonatal screening, so that the benefits of early diagnosis and treatment can be realized.

Molecular analysis of CYP-21 mutations for congenital adrenal hyperplasia in Singapore.

BACKGROUND: Congenital adrenal hyperplasia arising from 21-hydroxylase deficiency is associated with mutations in the CYP21 gene on chromosome 6p. This is the first report on the mutational spectrum of the CYP21 gene in Singapore. METHODS: To catalogue the mutations, ten exons of the CYP21 gene from 28 Singaporean patients were analyzed by PCR amplification and direct sequencing. RESULTS: Common mutations in descending order were the intron 2 splice site mutation (32.7% of the alleles), the I172N mutation (23.1% of the alleles), and the R356W mutation (19.2% of the alleles). Two potentially novel mutations were discovered: (1) duplication of 111 bp from codon 21 to codon 57 (exon 1) and (2) missense mutation (L261P, exon 7). There was generally a good genotype-phenotype correlation, allowing accurate prediction of the disease severity.

Mitochondrial tubulopathy: the many faces of mitochondrial disorders.

We report a rare presentation of mitochondrial disorder in a child with recurrent carpopedal spasms due to hypocalcemia and hypomagnesemia, secondary to renal proximal tubulopathy and possible hypoparathyroidism. At least two mutant mitochondrial DNA species were identified, and abnormal mitochondria were found in the muscle and renal biopsy specimens. The case illustrates the spectrum and diversity of mitochondrial presentations, arising because of heteroplasmy of mutations and the type of organs affected.

Prevalence of ICA and GAD antibodies at initial presentation of type 1 diabetes mellitus in Singapore children.

OBJECTIVE: To determine the prevalence of islet cell antibodies (ICA) and antibodies to glutamic acid decarboxylase (GAD) in Asian children with diabetes mellitus (DM) at the time of diagnosis. PATIENTS AND METHODS: 41 children were studied at their initial presentation from 1993 to 2000. RESULTS: Mean age of onset (+/- SD) of DM was 7.6 (+/- 4.2) years. One or both of the two autoantibodies, ICA and anti-GAD, were present in 17 of the 41 children (41.5%) at the time of diagnosis. Comparing the group of children with autoantibodies and the group without detectable autoantibodies, there were no significant differences in body mass index (15.4 vs. 16.3 kg/m2), age of onset (7.4 vs. 7.8 years), random C-peptide levels (203 vs. 311 pmol/l), HbA1c levels (13.2 vs. 12.7%), and frequency of diabetic ketoacidosis at presentation (53.3 vs. 55%). CONCLUSION: Prevalence of antibodies at presentation of DM in Singapore (41.5%) is lower than in Caucasian populations (60-90%). Other autoantibodies yet to be identified may be contributory. Alternatively, non-immune mediated mechanisms may be responsible for a significant proportion of type 1 DM in Singapore children.

Type II Gaucher disease: compound heterozygote with RecNciI and L444P mutations.

We report the phenotype and genotype of an Indonesian Chinese boy with type II Gaucher disease. He had a unique presentation of recurrent cyanosis from laryngospasm. He was compound heterozygous for L444P/L444P + A456P + V460V. There have been few reports of this heterozygosity and its phenoptype. This genotype-phenotype correlation will be important for physicians in genetic counselling. Type II Gaucher disease in Southeast Asia may not be as rare as was perceived, but may be a condition that is under-reported. The success of our technique together with the results have made it possible for us to perform prenatal diagnosis and carrier detection for the family.

IGFs and IGF-binding proteins in short children with steroid-dependent nephrotic syndrome on chronic glucocorticoids: changes with 1 year exogenous GH.

OBJECTIVE: Children with steroid-dependent nephrotic syndrome (SDNS), despite being in remission on glucocorticoids, continue to have growth retardation and short stature. The mechanism is uncertain as both chronic glucocorticosteroids and the nephrotic syndrome may independently affect growth. We investigated the changes in the IGFs and IGF-binding proteins (IGFBPs) in a group of short SDNS children, and studied the changes prospectively with 1 year's treatment with GH. DESIGN AND METHODS: Total and 'free' IGF-I, IGFBP-3 and acid-labile subunit (ALS) were studied in eight SDNS boys (mean age=12.6 years; mean bone age=9.1 years) on long term oral prednisolone (mean dose 0.46 mg/kg per day) before, during, and after, 1 year's treatment with GH (mean dose 0.32 mg/kg per week). Pretreatment comparisons were made with two control groups, one matched for bone age (CBA; mean bone age=9.2 years), and another for chronological age (CCA; mean chronological age=13 years). Subsequently, three monthly measurements of serum and urine IGFBPs were carried out in the GH-treated SDNS patients using Western ligand blot and Western immunoblot. RESULTS: Pre-treatment serum total IGF-I levels and the IGF-I/IGFBP-3 ratio were elevated significantly in SDNS compared with CBA, and were similar to CCA. Serum free IGF-I levels were elevated significantly compared with both control groups, but serum IGFBP-3 did not differ significantly. Urinary IGFBP-2, IGFBP-3 and ALS were detectable in the SDNS children only. With GH treatment, IGF-I and IGFBP-3, but not IGF-II, increased significantly compared with pre-treatment values, and returned to baseline after cessation of GH treatment. Urinary IGFBPs did not change significantly with GH treatment. CONCLUSIONS: There is persistent urinary loss of IGFBP-2, IGFBP-3 and ALS in children with SDNS in remission with growth retardation. However, the significant elevation in serum IGF-I suggests that glucocorticoid-induced resistance to IGF is the main factor responsible for the persistent growth retardation in these children. Exogenous GH was able to overcome this resistance by further increasing serum IGF-I.

Cyclic pamidronate infusion improves bone mineralisation and reduces fracture incidence in osteogenesis imperfecta.

UNLABELLED: A prospective open study was performed to determine the efficacy and safety of pamidronate in improving bone mineralisation and reducing fracture incidence in osteogenesis imperfecta (OI). Intravenous pamidronate was administered at 1.5 mg/kg bi-monthly to six children with OI, over 12-23 months. The number of fractures decreased from median of 3 (range 1-12) to 0 fractures/year (range 0-4) (P<0.05). After 12 months of treatment, there was significant improvement in areal bone mineral density (BMD) z-scores of the lumbar spine from median of -2.40 (range -3.20 to -1.67) to -1.90 (range -2.38 to -0.91) (P<0.05) and in the volumetric BMD which increased from median of 0.095 to 0.146 g/cm3 (P<0.05). Urine N-telopeptide levels (bone resorption marker) decreased from a median of 461.5 bone collagen equivalent/creatinine (BCE/Cr) (range 129-721 BCE/Cr) to 223.5 BCE/Cr (range 107-312 BCE/Cr) (P<0.05) and serum alkaline phosphatase (ALP) (bone formation marker) from a median of 230.0 U/l (range 148-305 U/l) to 133.5 U/l (range 79-233 U/l) (P<0.05), reflecting reduced bone turnover. This may represent a net reduction in bone resorption and provides a biochemical explanation for the increase in bone mineralisation. Height standard deviation scores were not affected and there were no significant adverse effects. CONCLUSION: 1 year cyclical pamidronate is effective and safe in improving bone mineralisation and reducing fracture incidence in osteogenesis imperfecta.

Sandhoff disease--a case report of 3 siblings and a review of potential therapies.

INTRODUCTION: Sandhoff disease is a GM2 gangliosidosis that may present within the first 6 months of life with developmental regression. This is the first report of a pedigree from Southeast Asia. CLINICAL PICTURE: All the affected siblings presented in the first year of life with developmental regression, spasticity, seizures and loss of vision. The diagnosis was confirmed by an enzymatic deficiency in both beta-hexosaminidase A and B. CONCLUSION: As the disorder is autosomal recessive, and no curative therapy is currently available, genetic counselling is necessary to prevent the burden of this devastating disease. We review the potential strategies of treatment for Sandhoff disease.

Prepubertal diagnosis of X-linked congenital adrenal hypoplasia presenting after infancy.

UNLABELLED: X-linked congenital adrenal hypoplasia (CAH) presents classically with adrenal insufficiency within the first 6 months of life, as the fetal adrenal cortex progressively involutes. However, there is increasing recognition of delayed presentation after infancy with the need for accurate molecular diagnosis to avoid an erroneous diagnosis of other more common causes of adrenal insufficiency in childhood. We report our genetic studies of a pedigree with two affected boys presenting with late onset X-linked CAH, diagnosed by the presence of a known W171X mutation of the DAX-1 gene, in whom the mother was an obligate heterozygote. Unlike other causes of adrenal insufficiency, the significance of this diagnosis lies in the important association of hypogonadotropic hypogonadism, and the provision of accurate genetic counselling. CONCLUSION: This study demonstrates that genetic analysis for X-linked congenital adrenal hypoplasia is essential to confirm the diagnosis in prepubertal patients presenting with adrenal insufficiency after infancy.

The molecular pathogenesis of obesity: an unfinished jigsaw puzzle.

INTRODUCTION: Obesity is a common but highly complex disease, which evolved from interactions of multiple genes and the environment. In the past decade, there have been major advances in our understanding of the molecular genetics and pathogenesis of obesity, especially with regards to the genetics and functions of chemical mediators and their receptors, such as leptin, the leptin receptor, neuropeptide Y, the melanocortin-4 receptor, agouti-related protein and the peroxisome-proliferator-activated receptor gamma 2. METHODOLOGY: Recent studies and reports on the obesity genes and chemical mediators were reviewed. RESULTS: Despite exciting discoveries of single gene mutations with haploinsufficiency in human subjects, and single-gene disorders resulting in obesity, most cases of obesity are likely the result of subtle interactions of several related genes with environmental factors, which favour the net deposition of calories as fat, culminating in the obese phenotype. Obesity is unlikely to be caused by a single gene defect unless it is extreme (body mass index > 60), or present in an isolated population group. However, research has established that genes at multiple loci may interact centrally to determine satiety, and peripherally to influence the metabolic rate of obese individuals. CONCLUSION: The mechanisms of action of these genes in the development of obesity are now being examined, with the aim of eventually discovering a therapeutic intervention for obesity.

An atypical kindred with X-linked adrenal hypoplasia congenita, normal puberty, and normal Dax-1 promoter and coding sequence.

We report a Chinese kindred with an atypical sex-linked form of isolated adrenal hypoplasia without hypogonadotropic hypogonadism. Evidence of sex linkage was supported by DNA analysis using three polymorphic markers from the X-chromosome: a restriction fragment length polymorphism 200 kb centromeric of the DAX-1 gene, a tetranucleotide repeat marker in the DAX-1 promoter (DAX-P), and a microsatellite in the Duchenne muscular dystrophy locus (3'-19). This pedigree therefore presents the novel phenotype of sex-linked hypoadrenalism without hypogonadotropic hypogonadism, with evidence of possible linkage to the DAX-1 gene. However, all three affected individuals were examined for mutations in the DAX-1 gene, and found to have no sequence anomalies in the coding region, splice sites or 5' non-coding region. This presentation may be due to a defect in the DAX-1 gene outside its known coding region, possibly modulated by functional polymorphisms at other loci, and/or environmental effects, or to a defect in a novel gene on the X chromosome which selectively influences adrenal development.

A novel parathyroid hormone (PTH)/PTH-related peptide receptor mutation in Jansen's metaphyseal chondrodysplasia.

Two heterozygous PTH/PTH-related peptide (PTHrP) receptor missense mutations were previously identified in patients with Jansen's metaphyseal chondrodysplasia (JMC), a rare form of short limb dwarfism associated with hypercalcemia and normal or undetectable levels of PTH and PTHrP. Both mutations, H223R and T410P, resulted in constitutive activation of the cAMP signaling pathway and provided a plausible explanation for the abnormalities in skeletal development and mineral ion homeostasis. In the present study we analyzed genomic DNA from four additional sporadic cases with JMC to search for novel activating mutations in the PTH/PTHrP receptor, to determine the frequency of the two previously identified missense mutations, H223R and T410P, and to determine whether different mutations present with different severity of the disease. The H223R mutation was identified in three novel JMC patients and is, therefore, to date the most frequent cause of JMC. In the fourth patient, a novel heterozygous missense mutation was found that changes isoleucine 458 in the receptor's seventh membrane-spanning region to arginine (I458R). In COS-7 cells expressing the human PTH/PTHrP receptor with the I458R mutation, basal cAMP accumulation was approximately 8 times higher than that in cells expressing the wild-type receptor despite impaired surface expression of the mutant receptor. Furthermore, the I458R mutant showed higher responsiveness to PTH than the wild-type receptor in its ability to activate both downstream effectors, adenylyl cyclase and phospholipase C. Like the H223R and the T410P mutants, the I458R mutant had no detectable effect on basal inositol phosphate accumulation. Overall, the patient with the I458R mutation exhibited clinical and biochemical abnormalities similar to those in patients with the previously identified H223R and T410P mutations.