Germline mutations and genotype-phenotype correlation in Asian Indian patients with pheochromocytoma and paraganglioma.

BACKGROUND: Genetic aetiology of pheochromocytoma (PCC) and paraganglioma (PGL) is increasingly being studied; however, Asian Indian data on this aspect are scarce. OBJECTIVE: To study the prevalence of germline mutations and genotype-phenotype correlation in Asian Indian PCC/PGL patients. DESIGN: In this study, 150 index patients (M:F, 73:77) with PCC/PGL were evaluated. Phenotypic data were collected. Germline mutations in five susceptibility genes (RET, VHL, SDHB, SDHD and SDHC) were tested by sequencing and NF1 was diagnosed according to phenotype. RESULT: Of the total population, 49 (32.7%) PCC/PGL patients had germline mutations (VHL: 23 (15.3%), RET: 13 (8.7%), SDHB: 9 (6%), SDHD: 2 (1.3%) and NF1: 2 (1.3%)). Amongst the 30 patients with familial and/or syndromic presentation, all had germline mutations (VHL: 14 (46.7%), RET: 13 (43.3%), SDHB: 1 (3.3%) and NF1: 2 (6.7%)). Out of 120 patients with apparently sporadic presentation, 19 (15.8%) had a germline mutation (VHL: 9 (7.5%), SDHB: 8 (6.7%) and SDHD: 2 (1.7%)). Mutation carriers were younger (29.9 ± 14.5 years vs 36.8 ± 14.9; P = 0.01) and had a higher prevalence of bilateral PCC (26.5% vs 2.9%, P < 0.001) and multifocal tumours (12.2% vs 0.96%, P = 0.06). Based on syndromic features, metastasis, location and number of tumours, around 96% mutations in our cohort could be detected by appropriately selected single gene testing. CONCLUSION: Asian Indians with PCC/PGL differ from Western cohorts in having preponderance of VHL mutations in multifocal tumours and apparently sporadic unilateral PCC. Syndromic presentation, metastasis, location and number of PCC/PGL can be effectively used for guiding genetic prioritisation.

Management of diabetes insipidus in children.

Diabetes Insipidus (DI) is a heterogeneous clinical syndrome of disturbance in water balance, characterized by polyuria (urine output > 4 ml/kg/hr), polydypsia (water intake > 2 L/m(2)/d) and failure to thrive. In children, Nephrogenic DI (NDI) is more common than Central DI (CDI), and is often acquired. The signs and symptoms vary with etiology, age at presentation and mode of onset. Neonates and infants with NDI are severely affected and difficult to treat. Diagnosis is based on the presence of high plasma osmolality and low urinary osmolality with significant water diuresis. Water deprivation test with vasopressin challenge, though has limitations, is done to differentiate NDI and CDI and diagnose their partial forms. Measurement of urinary aquaporin 2 and serum copeptin levels are being studied and show promising diagnostic potential. Magnetic Resonance Imaging (MRI) pituitary helps in the etiological diagnosis of CDI, absence of posterior pituitary bright signal being the pathognomic sign. If pituitary stalk thickening of < 2 mm is present, these children need to be monitored for evolving lesion. Neonates and young infants are better managed with fluids alone. Older children with CDI are treated with desmopressin. The oral form is safe, highly effective, with more flexibility of dosing and has largely replaced the intranasal form. In NDI besides treatment of the underlying cause, use of high calorie low solute diet and drugs to ameliorate water excretion (thiazide, amelioride, indomethacin) are useful. Children with NDI however well treated, remain short and have mental retardation on follow up.

Gender dichotomy in long term growth trajectories of children with 21-hydroxylase deficiency congenital adrenal hyperplasia.

AIM: To evaluate longitudinal growth in 21-hydroxylase deficiency congenital adrenal hyperplasia (CAH), factors contributing to this and outcome for BMI, weight (Wt) and height (Ht) in adolescence. METHODS: Multi-level longitudinal models were used to evaluate growth patterns of 45 salt wasters (SW) and 12 non-SW with CAH. RESULTS: Ht, Wt and BMI growth curves differed between SW and non-SW, and by gender. In contrast to SW and males, non-SW females showed a markedly different pattern with a progressive increase in Wt and BMI SDS over childhood and adolescence and only a slight gain in Ht SDS. BMI SDS remained above 0 after early childhood. Over the 15 years, the growth variables were negatively associated with fludrocortisone (FC) (shorter children were receiving larger doses) but not hydrocortisone (HC) doses nor FC and HC doses in the first year. CONCLUSION: The growth patterns in these children with CAH were influenced by age, gender, phenotype and FC treatment. There was a trend to increasing BMI from an early age, greater adiposity during childhood and females had disproportionately greater adiposity but shorter stature during adolescence. These patients therefore have a predisposition to obesity in childhood and later life independent of early corticosteroid treatment.