Raja Padidela

Genetic Overlap in Kallmann Syndrome, Combined Pituitary Hormone Deficiency, and Septo-Optic Dysplasia

CONTEXT Kallmann syndrome (KS), combined pituitary hormone deficiency (CPHD), and septo-optic dysplasia (SOD) all result from development defects of the anterior midline in the human forebrain. OBJECTIVE The objective of the study was to investigate whether KS, CPHD, and SOD have shared genetic origins. DESIGN AND PARTICIPANTS A total of 103 patients with either CPHD (n = 35) or SOD (n = 68) were investigated for mutations in genes implicated in the etiology of KS (FGFR1, FGF8, PROKR2, PROK2, and KAL1). Consequences of identified FGFR1, FGF8, and PROKR2 mutations were investigated in vitro. RESULTS Three patients with SOD had heterozygous mutations in FGFR1; these were either shown to alter receptor signaling (p.S450F, p.P483S) or predicted to affect splicing (c.336C>T, p.T112T). One patient had a synonymous change in FGF8 (c.216G>A, p.T72T) that was shown to affect splicing and ligand signaling activity. Four patients with CPHD/SOD were found to harbor heterozygous rare loss-of-function variants in PROKR2 (p.R85G, p.R85H, p.R268C). CONCLUSIONS Mutations in FGFR1/FGF8/PROKR2 contributed to 7.8% of our patients with CPHD/SOD. These data suggest a significant genetic overlap between conditions affecting the development of anterior midline in the human forebrain.

SLC29A3 gene is mutated in pigmented hypertrichosis with insulin-dependent diabetes mellitus syndrome and interacts with the insulin signaling pathway

Pigmented hypertrichotic dermatosis with insulin-dependent diabetes (PHID) syndrome is a recently described autosomal recessive disorder associated with predominantly antibody negative, insulin-dependent diabetes mellitus. In order to identify the genetic basis of PHID and study its relationship with glucose metabolism, we performed homozygosity mapping in five unrelated families followed by candidate gene sequencing. Five loss-of-function mutations were identified in the SLC29A3 gene which encodes a member of a highly conserved protein family that transports nucleosides, nucleobases and nucleoside analogue drugs, hENT3. We show that PHID is allelic with a related syndrome without diabetes mellitus, H syndrome. The interaction of SLC29A3 with insulin signaling pathways was then studied using an established model in Drosophila melanogaster. Ubiquitous knockdown of the Drosophila ortholog of hENT3, dENT1 is lethal under stringent conditions; whereas milder knockdown induced scutellar bristle phenotypes similar to those previously reported in the knockdown of the Drosophila ortholog of the Islet gene. A cellular growth assay showed a reduction of cell size/number which could be rescued or enhanced by manipulation of the Drosophila insulin receptor and its downstream signaling effectors, dPI3K and dAkt. In summary, inactivating mutations in SLC29A3 cause a syndromic form of insulin-dependent diabetes in humans and in Drosophila profoundly affect cell size/number through interactions with the insulin signaling pathway. These data suggest that further investigation of the role of SLC29A3 in glucose metabolism is a priority for diabetes research.

Elevated basal and post-feed glucagon-like peptide 1 (GLP-1) concentrations in the neonatal period

BACKGROUND Glucagon-like peptide 1 (GLP-1) is an incretin hormone that stimulates glucose-induced insulin secretion, increases beta-cell proliferation, neogenesis and beta-cell mass. In adults, plasma concentrations of amidated GLP-1 are typically within the 5-10 pmol/l range in the fasting state and increases to approximately 50 pmol/l after ingestion of a mixed meal. RESEARCH DESIGN AND METHODS We measured plasma glucose, insulin and amidated forms of GLP-1 prefeed and then at 20 and 60 min post-feed following ingestion of a 60-70 ml of standard milk feed in preterm (n=10, 34-37 weeks) and term newborn infants (n=12, 37-42 weeks). Reverse-phase fast protein liquid chromatography was used to characterise the molecular nature of the circulating GLP-1. RESULTS Mean birth weight was 3.18 kg and mean age at sampling for GLP-1 was 7.7 days. The mean basal GLP-1 concentration was 79.1 pmol/l, which increased to 156.6 pmol/l (+/-70.9, P<0.001) and 121.5 pmol/l (+/-59.2) at 20 and 60 min respectively. Reverse-phase chromatography analysis suggested that the majority of GLP-1 immunoreactivity (>75%) represented GLP-1 (7-36) amide and (9-36) amide. CONCLUSIONS Basal and post-feed amidated GLP-1 concentrations in neonates are grossly raised with the major fractions of circulating GLP-1 being (7-36) amide and (9-36) amide. Elevated GLP-1 concentrations in the newborn period may have a role in regulating maturation of enteroendocrine system and also of increasing pancreatic beta-cell mass and regeneration. The high levels of GLP-1 may be due to immaturity of the dipeptidyl peptidase IV and or lower glomerular filtration rate in the neonatal period. Further studies are required to understand the role of GLP-1 in the neonatal period.

Abnormal Neurodevelopmental Outcomes are Common in Children with Transient Congenital Hyperinsulinism

Introduction: Neuroglycopenia is recognized to be associated with abnormal neurodevelopmental outcomes in 26–44% of children with persistent congenital hyperinsulinism (P-CHI). The prevalence of abnormal neurodevelopment in transient CHI (T-CHI) is not known. We have aimed to investigate abnormal neurodevelopment and associated factors in T-CHI and P-CHI. Materials and Methods: A cohort of children with CHI (n = 67, age 2.5–5 years) was assessed at follow-up review and noted to have normal or abnormal (mild or severe) neurodevelopmental outcomes for the domains of speech and language, motor, and vision. Children were classified as P-CHI (n = 33), if they had undergone surgery or remained on medical therapy, or T-CHI (n = 34), if medical treatment for hypoglycemia was stopped. Results: Overall, abnormal neurodevelopment was present in 26 (39%) children with CHI, of whom 18 (69%) were severe. Importantly, the incidence of abnormal neurodevelopment in T-CHI was similar to that in P-CHI (30 vs. 47% respectively, p = 0.16). The prevalence of severe abnormal neurodevelopment in speech, motor, and vision domains was similar in both T-CHI and P-CHI children. For this cohort, we found that the severity of disease [based upon maximal diazoxide dose (odds ratio 95% confidence intervals) 1.3 (1.1; 1.5), p = 0.03], and early presentation of CHI <7 days following birth [5.9 (1.3; 27.8), p = 0.02] were significantly associated with abnormal neurodevelopment. There was no significant association with gender, genotype, or the histopathological basis of CHI. Conclusion: Abnormal neurodevelopment was evident in one third of children with both T-CHI and P-CHI, early presentation and severe CHI being risk factors. Early recognition and rapid correction of hypoglycemia are advocated to avoid abnormal neurodevelopment in children with CHI.

Integrating genetic and imaging investigations into the clinical management of congenital hyperinsulinism

Congenital Hyperinsulinism (CHI) is a rare but important cause of hypoglycaemia in infancy. CHI is a heterogeneous disease, but has a strong genetic basis; a number of genetic causes have been identified with CHI in about a third of individuals, chiefly in the genes that code for the ATP sensitive K+ channels (KATP) in the pancreatic β‐cells. Rapid KATP channel gene testing is a critical early step in the diagnostic algorithm of CHI, with paternal heterozygosity correlating with the occurrence of focal lesions. Imaging investigations to diagnose and localize solitary pancreatic foci have evolved over the last decade with (18)F‐DOPA PET‐CT scanning as the current diagnostic tool of choice. Although clinical management of CHI has improved significantly with the application of genetic screening and imaging investigations, much remains to be uncovered. This includes a better understanding of the molecular mechanisms for dysregulated insulin release in those patients without known genetic mutations, and the development of biomarkers that could characterize CHI, including long‐term prognosis and targeted treatment planning, i.e. ‘personalised medicine’. From the perspective of pancreatic imaging, it would be important to achieve greater specificity of diagnosis not only for focal lesions but also for diffuse and atypical forms of the disease.

Abnormal Growth in Noonan Syndrome: Genetic and Endocrine Features and Optimal Treatment

Noonan syndrome (NS) is a phenotypically heterogeneous syndrome which is frequently associated with short stature. Recent genetic investigations have identified mutations in five genes, namely PTPN11, KRAS, SOS1, NF1 and RAF1 in patients with the NS phenotype. PTPN11 is the commonest, being present in approximately 50% of cases. The degree of short stature in children does not associate closely with the presence of mutations, however some PTPN11-positive patients have decreased GH-dependent growth factors consistent with mild GH insensitivity. GH therapy, using doses similar to those approved for Turner syndrome (TS), induced short-term increases in height velocity over 1–3 years, and may improve final adult height with longer-term treatment.

Diabetes mellitus, exocrine pancreatic deficiency, hypertrichosis, hyperpigmentation, and chronic inflammation: confirmation of a syndrome

Abstract:  Type 1 diabetes mellitus is characterized by dysregulation of the immune system leading to inflammation and selective destruction of pancreatic beta cells. Mild to moderate pancreatic exocrine insufficiency is found in patients with type 1 diabetes. Diabetes mellitus may also be part of a syndrome occasionally involving hair and skin abnormalities. We report our observations on two siblings with insulin‐dependent diabetes, severe exocrine pancreatic deficiency, pigmented hypertrichotic skin patches with induration and chronic inflammation. The first sibling presented at the age of 9 months with hypertrichosis and hyperpigmentation, particularly on her back and legs and then developed diabetes mellitus at the age of 4 yr. The second sibling presented with exactly the same clinical features but at a later age of 12 yr. Both siblings had severe pancreatic exocrine deficiency with chronic persistent inflammation. Some of the clinical features in these siblings resemble those described by Prendiville et al. although our patients had additional features. The chronic inflammatory response in both siblings is highly suggestive of some form of immune dysregulation. The presence of consanguinity in the parents and similarity of clinical features in the siblings are suggestive of a novel autoimmune disorder, possibly secondary to autosomal recessive inheritance.

Mineralocorticoid Deficiency and Treatment in Congenital Adrenal Hyperplasia

Approximately 75%–80% of patients with Congenital Adrenal Hyperplasia (CAH) fail to synthesize sufficient mineralocorticoids to maintain salt and water balance. In most instances genotype can predict mineralocorticoid deficiency in CAH. Early recognition and replacement with 9-fludrocortisone and salt supplements will prevent development of potentially lethal salt losing crises. In infancy a relative state of aldosterone resistance exists and replacement dose of 9-fludrocortisone based on body surface area is higher during infancy compared to childhood and adults. Salt supplementation is generally not required after weaning is started. Regular monitoring of blood pressure and measurements of plasma electrolytes and renin are required to prevent complications of under or over dosage.

Mutation in the TBCE Gene Is Associated with Hypoparathyroidism-Retardation-Dysmorphism Syndrome Featuring Pituitary Hormone Deficiencies and Hypoplasia of the Anterior Pituitary and the Corpus Callosum

CONTEXT Hypoparathyroidism-retardation-dysmorphism (HRD) syndrome, an autosomal recessive disorder characterized by distinct clinical, biochemical, and genetic abnormalities, is characterized by severe short stature, the etiology of which is unclear. Homozygous mutation of the tubulin cofactor E (TBCE) gene leading to loss of four amino acids (c.155-166del12; p.del 52-55) in the TBCE protein has been associated with the syndrome. AIM The aim of the study was to describe the clinical, biochemical, and neuroradiological features of children with genetically proven HRD syndrome. METHODS Six children from four independent Middle Eastern pedigrees with clinical features of HRD syndrome were confirmed to have the previously reported homozygous mutation in TBCE (c.155-166del12) and were investigated with magnetic resonance imaging (MRI) of the brain and standard pituitary function testing. RESULTS Cranial MRI in all children showed severe hypoplasia of the anterior pituitary and corpus callosum, with decreased white matter bulk. Four of five children tested had subnormal GH and cortisol responses to glucagon, and plasma IGF-I concentration was low in all six children. Cortisol response to synacthen was suboptimal in one of three patients tested. Male children (n = 3) had clinical features suggestive of hypogonadotropic hypogonadism. CONCLUSION GH insufficiency, hypocortisolemia, and abnormal cranial MRI appear to be associated with HRD syndrome and may contribute in part to the short stature. Our data support the need for longer term monitoring for evolving pituitary hormone deficiencies and raise the possibility that TBCE may play a role in development of the anterior pituitary, corpus callosum, and white matter in addition to the parathyroid glands.

Drug-induced hepatitis following use of octreotide for long-term treatment of congenital hyperinsulinism

Congenital hyperinsulinism (CHI) is a rare disorder of hypoglycaemia in children due to excessive and dysregulated insulin secretion. Octreotide, a somatostatin analogue, is used in the treatment of hypoglycaemia in Diazoxide unresponsive CHI, but is associated with side effects such as gastrointestinal dysmotility and rarely, necrotising enterocolitis. It would be important to recognise rare but serious side effects from Octreotide therapy, particularly with long-term use. In this report, we have described drug-induced hepatitis with moderately high doses of Octreotide in a child with diffuse CHI. While serum alanine transaminase levels rose significantly with Octreotide therapy (maximum dose 30 μg/kg/day), hepatitis resolved following discontinuation of medical treatment. Liver enzymes should be monitored routinely in children with CHI using long-term Octreotide treatment, particularly with high doses. The presence of drug-induced hepatitis should prompt discontinuation of Octreotide treatment with likely subsequent resolution.