A novel TRPM6 variant (c.3179T>A) causing familial hypomagnesemia with secondary hypocalcemia

SUMMARY

Familial hypomagnesemia with secondary hypocalcemia (FHSH) is a rare autosomal recessive disorder (OMIM# 602014) characterized by profound hypomagnesemia associated with hypocalcemia. It is caused by mutations in the gene encoding transient receptor potential cation channel member 6 (TRPM6). It usually presents with neurological symptoms in the first months of life. We report a case of a neonate presenting with recurrent seizures and severe hypomagnesemia. The genetic testing revealed a novel variant in the TRPM6 gene. The patient has been treated with high-dose magnesium supplementation, remaining asymptomatic and without neurological sequelae until adulthood. Early diagnosis and treatment are important to prevent irreversible neurological damage.

LEARNING POINTS

Loss-of-function mutations of TRPM6 are associated with FHSH. FHSH should be considered in any child with refractory hypocalcemic seizures, especially in cases with serum magnesium levels as low as 0.2 mM. Normocalcemia and relief of clinical symptoms can be assured by administration of high doses of magnesium. Untreated, the disorder may be fatal or may result in irreversible neurological damage.

Congenital hyperreninemic hypoaldosteronism due to aldosterone synthase deficiency type I in a Portuguese patient - Case report and review of literature

Hyperreninemic hypoaldosteronism due to aldosterone synthase (AS) deficiency is a rare condition typically presenting as salt-wasting syndrome in the neonatal period. A one-month-old Portuguese boy born to non-consanguineous parents was examined for feeding difficulties and poor weight gain. A laboratory workup revealed severe hyponatremia, hyperkaliaemia and high plasma renin with unappropriated normal plasma aldosterone levels, raising the suspicion of AS deficiency. Genetic analysis showed double homozygous of two different mutations in the CYP11B2 gene: p.Glu198Asp in exon 3 and p.Val386Ala in exon 7. The patient maintains regular follow-up visits in endocrinology clinics and has demonstrated a favourable clinical and laboratory response to mineralocorticoid therapy. To our knowledge, this is the first Portuguese case of AS deficiency reported with confirmed genetic analysis.

Endoscopic ultrasound-guided ethanol ablation therapy for pancreatic insulinoma: an unusual strategy

Summary

Insulinomas are the most frequent cause of hyperinsulinaemic hypoglycaemia. Although surgical enucleation is the standard treatment, a few other options are available to high-risk patients who are elderly or present with co-morbidities. We present a case report of an 89-year-old female patient who was admitted to the emergency department due to recurrent hypoglycaemia, especially during fasting. Laboratory work-up raised the suspicion of hyperinsulinaemic hypoglycaemia, and abdominal CT scan revealed a 12 mm nodular hypervascular lesion of the pancreatic body suggestive of neuroendocrine tumour. The patient was not considered a suitable candidate for surgery, and medical therapy with diazoxide was poorly tolerated. Endoscopic ultrasound-guided ethanol ablation therapy was performed and a total of 0.6 mL of 95% ethanol was injected into the lesion by a transgastric approach; no complications were reported after the procedure. At 5 months of follow-up, no episodes of hypoglycaemia were reported, no diazoxide therapy was necessary, and revaluation abdominal CT scan revealed a pancreatic nodular lesion with a size involution of about half of its original volume. The patient is regularly followed-up at the endocrinology clinic and shows a significant improvement in her wellbeing and quality of life.

Learning points:

Diffuse large B-cell lymphoma of the adrenal gland: a rare cause of primary adrenal insufficiency

Although it is a rare entity, primary lymphoma of the adrenal gland should be considered in the differential diagnosis of bilateral nodular adrenal lesions, particularly when there is evidence of associated adrenal insufficiency. We describe the case of an 83-year-old woman admitted to the emergency department due to a month's history of asthenia, weight loss, anorexia and nausea. Abdominopelvic CT showed bilateral nodular lesions of adrenal glands and a stimulation test with tetracosactide was compatible with primary adrenal insufficiency. CT-guided biopsy of the left adrenal gland was performed, and histopathological results were consistent with diffuse large B-cell lymphoma. Positron emission tomography (18)F-fluorodeoxyglucose detected two intensely hypermetabolic lesions limited to both adrenal glands. Replacement therapy with hydrocortisone 15 mg/day and fludrocortisone 0.1 mg/day was promptly started and chemotherapy with rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone was initiated after haematology-oncology consultation.