Dinesh Giri

Novel FOXA2 mutation causes Hyperinsulinism, Hypopituitarism with Craniofacial and Endoderm-derived organ abnormalities

Congenital hypopituitarism (CH) is characterized by the deficiency of one or more pituitary hormones and can present alone or in association with complex disorders. Congenital hyperinsulinism (CHI) is a disorder of unregulated insulin secretion despite hypoglycaemia that can occur in isolation or as part of a wider syndrome. Molecular diagnosis is unknown in many cases of CH and CHI. The underlying genetic etiology causing the complex phenotype of CH and CHI is unknown. In this study, we identified a de novo heterozygous mutation in the developmental transcription factor, forkhead box A2, FOXA2 (c.505T>C, p.S169P) in a child with CHI and CH with craniofacial dysmorphic features, choroidal coloboma and endoderm-derived organ malformations in liver, lung and gastrointestinal tract by whole exome sequencing. The mutation is at a highly conserved residue within the DNA binding domain. We demonstrated strong expression of Foxa2 mRNA in the developing hypothalamus, pituitary, pancreas, lungs and oesophagus of mouse embryos using in situ hybridization. Expression profiling on human embryos by immunohistochemistry showed strong expression of hFOXA2 in the neural tube, third ventricle, diencephalon and pancreas. Transient transfection of HEK293T cells with Wt (Wild type) hFOXA2 or mutant hFOXA2 showed an impairment in transcriptional reporter activity by the mutant hFOXA2. Further analyses using western blot assays showed that the FOXA2 p.(S169P) variant is pathogenic resulting in lower expression levels when compared with Wt hFOXA2. Our results show, for the first time, the causative role of FOXA2 in a complex congenital syndrome with hypopituitarism, hyperinsulinism and endoderm-derived organ abnormalities.

Novel compound heterozygous ASXL3 mutation causing Bainbridge-ropers like syndrome and primary IGF1 deficiency

BackgroundDe novo truncating and splicing mutations in the additional sex combs-like 3 (ASXL3) gene have been implicated in the development of Bainbridge-Ropers syndrome (BRPS) characterised by severe developmental delay, feeding problems, short stature and characteristic facial features.Case presentationWe describe, for the first time, a patient with severe short stature, learning difficulties, feeding difficulties and dysmorphic features with a novel compound heterozygous mutation in ASXL3.Additionally the patient also has primary insulin like growth factor-1 (IGF1) deficiency. The mutations occur in exon 11 and proximal part of exon 12 and are strongly conserved at the protein level across various species. In-silico analyses using PolyPhen-2 and SIFT predict the amino acid substitutions to be potentially deleterious to the protein function. Detailed bioinformatics analysis show that the molecular defects caused by the two compound heterozygous mutations synergistically impact on two points of the molecular interaction network of ASXL3.ConclusionWe hypothesise that ASXL3 potentially has a role in transcriptional activation of IGF1 involved in signalling pathways that regulate cell proliferation and growth, which could be contributing to short stature encountered in these patients.

Testosterone Therapy Improves the First Year Height Velocity in Adolescent Boys with Constitutional Delay of Growth and Puberty

Background Constitutional delay of growth and puberty (CDGP) can cause significant psychological distress in adolescent boys. Although testosterone usage in this group has not been shown to affect the final adult height, the effect on the first year height velocity has not been widely reported. Objectives The aim is to determine whether testosterone treatment improves the first year height velocity in boys with CDGP when compared to boys with CDGP who go through puberty spontaneously Methods Retrospective data from 23 adolescent boys with CDGP was analysed. Ten out of 23 boys (43%) received testosterone injection (testosterone enanthate, 125 mg), once every 6 weeks for 3 doses in total. Both the groups (treated and untreated) had their height, bone age and testicular volume measured at the baseline, The height velocity and final predicted adult height were compared at the end of one year between both the groups. Results In the testosterone-untreated group, the mean (± SD) chronological age, bone age, height standard deviation scores (SDS) and testicular volume were 14.3 years (± 0.3),12.1 years (± 1.6), -1.9 (± 0.8) and 4.7 mL (± 1.1) respectively. Within the testosterone-treated group the mean (± SD) chronological age, bone age, height SDS and testicular volume at presentation were 14.4 years (± 0.4), 11 years (± 1.6), -2.1 SD(± 0.6) and 4.5 mL (± 1.2) respectively. The mean age of treatment with testosterone was 14.4 years (± 0.44). The mean height velocity one year after treatment was 8.4 cm/year (± 1.7) in the testosterone treated group when compared to 6.1 cm/year (± 2.1) in the patients who did not receive treatment (P = 0.01). There was no significant difference in the final predicted height between the 2 groups (P = 0.15). Conclusions Testosterone therapy improves the first year height velocity in boys with CDGP, without influencing their final predicted height.

Congenital hyperinsulinism and Poland syndrome in association with 10p13–14 duplication

Summary Poland syndrome (PS) is a rare congenital condition, affecting 1 in 30 000 live births worldwide, characterised by a unilateral absence of the sternal head of the pectoralis major and ipsilateral symbrachydactyly occasionally associated with abnormalities of musculoskeletal structures. A baby girl, born at 40 weeks’ gestation with birth weight of 3.33 kg (−0.55 SDS) had typical phenotypical features of PS. She had recurrent hypoglycaemic episodes early in life requiring high concentration of glucose and glucagon infusion. The diagnosis of congenital hyperinsulinism (CHI) was biochemically confirmed by inappropriately high plasma concentrations of insulin and C-peptide and low plasma free fatty acids and β-hydroxyl butyrate concentrations during hypoglycaemia. Sequencing of ABCC8, KCNJ11 and HNF4A did not show any pathogenic mutation. Microarray analysis revealed a novel duplication in the short arm of chromosome 10 at 10p13–14 region. This is the first reported case of CHI in association with PS and 10p duplication. We hypothesise that the HK1 located on the chromosome 10 encoding hexokinase-1 is possibly linked to the pathophysiology of CHI. Learning points: Congenital hyperinsulinism (CHI) is known to be associated with various syndromes. This is the first reported association of CHI and Poland syndrome (PS) with duplication in 10p13–14. A potential underlying genetic link between 10p13–14 duplication, PS and CHI is a possibility.

A Rare Case of Heterozygous Gain of Function Thyrotropin Receptor Mutation Associated with Development of Thyroid Follicular Carcinoma

Activating mutations in thyrotropin receptor (TSHR) have been previously described in the context of nonautoimmune hyperthyroidism and thyroid adenomas. We describe, for the first time, a mutation in TSHR contributing to follicular thyroid carcinoma (FTC) in an adolescent. A 12-year-old girl presented with a right-sided neck swelling, increasing in size over the previous four weeks. Clinical examination revealed a firm, nontender thyroid nodule. Ultrasound scan of the thyroid showed a heterogeneous highly vascular mass. Thyroid function tests showed suppressed TSH [<0.03mU/L], normal FT4 [10.1pmol/L, 9-19], and raised FT3 [9.1pmol/L, 3.6-6.4]. Thyroid [TPO and TRAB] antibodies were negative. A right hemithyroidectomy was performed and the histology of the sample revealed follicular carcinoma with mild to moderate nuclear pleomorphism and evidence of capsular and vascular invasion (pT1b). Sanger sequencing of DNA extracted from the tumour tissue revealed a missense somatic mutation (c.1703T>C, p.Ile568Thr) in TSHR. Papillary thyroid carcinomas constitute the most common thyroid malignancy in childhood, while FTC is rare. FTC due to TSHR mutation suggests an underlying, yet to be explored, molecular pathway leading to the development of malignancy. The case is also unique in that the clinical presentation of FTC as a toxic thyroid nodule has not been previously reported in children.