The ICET-A Recommendations for the Diagnosis and Management of Disturbances of Glucose Homeostasis in Thalassemia Major Patients

Iron overload in patients with thalassemia major (TM) affects glucose regulation and is mediated by several mechanisms. The pathogenesis of glycaemic abnormalities in TM is complex and multifactorial. It has been predominantly attributed to a combination of reduced insulin secretory capacity and insulin resistance. The exact mechanisms responsible for progression from norm glycaemia to overt diabetes in these patients are still poorly understood but are attributed mainly to insulin deficiency resulting from the toxic effects of iron deposited in the pancreas and insulin resistance. A group of endocrinologists, haematologists and paediatricians, members of the International Network of Clinicians for Endocrinopathies in Thalassemia and Adolescence Medicine (ICET-A) convened to formulate recommendations for the diagnosis and management of abnormalities of glucose homeostasis in thalassemia major patients on the basis of available evidence from clinical and laboratory data and consensus practice. The results of their work and discussions are described in this article.

Comprehensive genotyping and clinical characterisation reveal 27 novel NKX2-1 mutations and expand the phenotypic spectrum

BACKGROUND

NKX2-1 encodes a transcription factor with large impact on the development of brain, lung and thyroid. Germline mutations of NKX2-1 can lead to dysfunction and malformations of these organs. Starting from the largest coherent collection of patients with a suspected phenotype to date, we systematically evaluated frequency, quality and spectrum of phenotypic consequences of NKX2-1 mutations.

METHODS

After identifying mutations by Sanger sequencing and array CGH, we comprehensively reanalysed the phenotype of affected patients and their relatives. We employed electrophoretic mobility shift assay (EMSA) to detect alterations of NKX2-1 DNA binding. Gene expression was monitored by means of in situ hybridisation and compared with the expression level of MBIP, a candidate gene presumably involved in the disorders and closely located in close genomic proximity to NKX2-1.

RESULTS

Within 101 index patients, we detected 17 point mutations and 10 deletions. Neurological symptoms were the most consistent finding (100%), followed by lung affection (78%) and thyroidal dysfunction (75%). Novel symptoms associated with NKX2-1 mutations comprise abnormal height, bouts of fever and cardiac septum defects. In contrast to previous reports, our data suggest that missense mutations in the homeodomain of NKX2-1 not necessarily modify its DNA binding capacity and that this specific type of mutations may be associated with mild pulmonary phenotypes such as asthma. Two deletions did not include NKX2-1, but MBIP, whose expression spatially and temporarily coincides with NKX2-1 in early murine development.

CONCLUSIONS

The high incidence of NKX2-1 mutations strongly recommends the routine screen for mutations in patients with corresponding symptoms. However, this analysis should not be confined to the exonic sequence alone, but should take advantage of affordable NGS technology to expand the target to adjacent regulatory sequences and the NKX2-1 interactome in order to maximise the yield of this diagnostic effort.

Growth and endocrine disorders in thalassemia: The international network on endocrine complications in thalassemia (I-CET) position statement and guidelines

The current management of thalassemia includes regular transfusion programs and chelation therapy. It is important that physicians be aware that endocrine abnormalities frequently develop mainly in those patients with significant iron overload due to poor compliance to treatment, particularly after the age of 10 years. Since the quality of life of thalassemia patients is a fundamental aim, it is vital to monitor carefully their growth and pubertal development in order to detect abnormalities and to initiate appropriate and early treatment. Abnormalities should be identified and treatment initiated in consultation with a pediatric or an adult endocrinologist and managed accordingly. Appropriate management shall put in consideration many factors such as age, severity of iron overload, presence of chronic liver disease, thrombophilia status, and the presence of psychological problems. All these issues must be discussed by the physician in charge of the patient's care, the endocrinologist and the patient himself. Because any progress in research in the field of early diagnosis and management of growth disorders and endocrine complications in thalassemia should be passed on to and applied adequately to all those suffering from the disease, on the 8 May 2009 in Ferrara, the International Network on Endocrine Complications in Thalassemia (I-CET) was founded in order to transmit the latest information on these disorders to the treating physicians. The I-CET position statement outlined in this document applies to patients with transfusion-dependent thalassemia major to help physicians to anticipate, diagnose, and manage these complications properly.

International network on endocrine complications in thalassaemia (I-CET): an opportunity to grow

Most of the endocrine complications in thalassaemia are attributable to iron overload which may be the result of economic circumstances (expense of the chelation therapy), late onset of chelation therapy or poor compliance with the iron chelation therapy. The major difficulties reported by hematologists or pediatric endocrinologists experienced in thalassaemias or thalassaemia syndromes in following growth disorders and endocrine complications were: lack of familiarity with medical treatment of endocrine complications (40%), interpretation of endocrine tests (30%), costs (65%), absence of paediatric endocrinologist for consultation on growth disorders and endocrine complications (27%), facilities (27%), other (e.g. lack of collaboration and on-time consultation between thalassaemic Centers supervised by hematologists and endocrinologists) (17%). Because any progress we make in research into growth disorders and endocrine complications in thalassaemia should be passed on to all those suffering from it, guaranteeing them the same therapeutic benefits and the same quality of life, on the 8th of May, 2009 in Ferrara (Italy), the International Network on Endocrine Complications in Thalassemia (I-CET) was founded. The I-CET group is planning to conduct, in Ferrara in May 2012, a workshop, "MRI and Endocrine Complications in Thalassaemia", and in Doha (Qatar) in September 2012, a 3-day intensive course entitled, "Growth disorders and Endocrine Complications in Thalassaemia", to provide interested pediatricians, physicians and hematologists from all over the world with an in-depth approach to the diagnosis and management of growth and endocrine disorders in thalassaemic patients.

Plasma aldosterone response to metoclopramide in patients with Cushing's disease

The acute effect of metoclopramide on aldosterone and prolactin levels were studied in 8 control subjects and 11 patients with Cushing's disease. Metoclopramide (10 mg i.v.) induced a similar plasma prolactin response in control subjects and patients. No difference was found in basal aldosterone levels between the two groups. Apart from a more delayed aldosterone response to metoclopramide in the Cushing's disease group, no significant difference in the peak aldosterone values was found between the patients and controls. The short-term treatment with DA2-receptor agonist bromocriptine was without effect on aldosterone response to metoclopramide in the Cushing's disease group. These results argue against an altered dopaminergic control of aldosterone secretion in patients with Cushing's disease. The lack of a bromocriptine effect on aldosterone response to metoclopramide is in accordance with the concept that the dopamine receptors involved in aldosterone regulation differ from classical DA2 receptors.

Novel mutations of the thyroid peroxidase gene in patients with permanent congenital hypothyroidism

OBJECTIVE

It is suggested that iodide organification defects account for 10% of all cases with congenital hypothyroidism (CH). One candidate gene for these defects is the thyroid peroxidase (TPO) gene.

DESIGN

Exons 2, 8-10 and 14 of the TPO gene were examined in 30 patients with permanent CH without a family history of CH. This group was characterized by the presence of an orthotopic thyroid gland and elevated TSH levels.

METHODS

The mutational screening was performed by single-strand conformational polymorphism followed by sequence analysis of fragments with abnormal migration patterns and by restriction enzyme analysis.

RESULTS

In four patients we were able to identify mutations on both alleles which have not been described so far. One patient was a carrier of a new homozygous point mutation in exon 9 resulting in an exchange from Leu to Pro at codon 458. Another patient was found to be compound heterozygous for two mutations, a 20 bp duplication in exon 2 and a new mutation in exon 9 (Arg491His). Two brothers of consanguineous parents showed a homozygous T deletion in exon 14 at position 2512.

CONCLUSIONS

Our findings confirm the genetic heterogeneity of TPO defects and support the suggested prevalence of organification defects.

Neonatal TSH screening--an instrument of iodine supplementation monitoring in Bulgaria in comparison to Berlin--a preliminary report

The challenge to eradicate iodine deficiency disorders (IDD) by the year 2000 worldwide will have positive consequences for more than 20 million people suffering from IDD. This is the main and common goal for the developing but also for a lot the developed countries. Sensitive tools like neonatal thyroid screening (NTS) can be used in order to make changes in iodine supplementation more transparent and to have a dynamic target oriented approach. The comparison between six districts in Bulgaria and Berlin revealed despite of some positive changes after the fortification of the iodine supplementation program still existing iodine deficiency in Bulgaria which is more profound than in Berlin in 1990. The shift to higher TSH-values in the Black-Sea region, classified by goitre-prevalence in 1956 as non-endemic for iodine deficiency, needs further investigation. Besides of iodine deficiency an influence of iodine-containing disinfectants and/or goitrogens is possible.

Aldosterone response to metoclopramide in patients with prolactinoma: effect of short-term bromocriptine treatment

The acute effect of 10 mg metoclopramide i.v. on prolactin and aldosterone levels was studied in 8 women with prolactinoma and 8 normal women. The prolactin response to metoclopramide was blunted in hyperprolactinemic patients in comparison with controls. Metoclopramide induced similar aldosterone increases in patients and controls, but hyperprolactinemic women showed a more sustained aldosterone response. Bromocriptine treatment (10 mg daily p.o. for 5 days) in patients with prolactinoma completely suppressed the prolactin response to metoclopramide and the aldosterone response curve was very similar to that of controls. The results did not exclude some degree of suppression of aldosterone in response to bromocriptine.

Role of prostaglandin E2 (PGE2) on the corticotropin-releasing hormone (CRH)-induced ACTH release in healthy men

The effect of PGE2 on ACTH and cortisol responses to CRH was studied in 6 healthy men who received CRH i.v. during either saline or PGE2 infusions which were started 60 min. before testing. ACTH and cortisol responses to CRH were greater during PGE2 infusion compared to the control study. The results indicate that PGE2 positively modulates CRH-induced ACTH secretion.

Serum aldosterone response to metoclopramide in normal subjects and acromegalic patients

The acute effects of metoclopramide on aldosterone and prolactin levels were studied in 11 normal subjects, 8 normotensive and 8 hypertensive acromegalics. Metoclopramide (10 mg i.v.) induced a similar serum aldosterone increase in normal subjects and normotensive acromegalics. Hypertensive acromegalics showed elevated basal serum aldosterone level and blunted aldosterone response to metoclopramide. The prolactin response to metoclopramide was blunted in acromegalics in comparison with normal subjects but the difference was statistically significant only in hypertensive patients. The blunted aldosterone and prolactin responses to metoclopramide in hypertensive acromegalics suggest that there is a dopamine deficiency at central and adrenal level in these patients.

Corticotropin-releasing factor (CRF) stimulation test in normal subjects and patients with Cushing's syndrome

The hormonal responses to human corticotropin-releasing factor (hCRF) were investigated in 6 normal subjects, 13 patients with Cushing's disease (8 with diffuse bilateral hyperplasia and 5 with nodular hyperplasia) and one patient with Cushing's syndrome due to an adrenal adenoma. hCRF (100 micrograms i.v.) was a potent stimulant of ACTH and cortisol in normal subjects. Patients with Cushing's disease due to diffuse hyperplasia showed variable ACTH and cortisol responses to hCRF. In both normal subjects and in patients hCRF consistently stimulated serum aldosterone levels. Patients with nodular hyperplasia had extremely suppressed plasma ACTH levels and no responses of ACTH, cortisol and aldosterone to hCRF like in the patient with adrenal adenoma. Our results suggest that hCRF-stimulation test may be a useful tool for differentiating pituitary and adrenal forms of Cushing's syndrome.