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Open access

Rowena Speak, Jackie Cook, Barney Harrison, and John Newell-Price

Mutations of the rearranged during transfection (RET) proto-oncogene, located on chromosome 10q11.2, cause multiple endocrine neoplasia type 2A (MEN2A). Patients with mutations at the codon 609 usually exhibit a high penetrance of medullary thyroid cancer (MTC), but a sufficiently low penetrance of phaeochromocytoma that screening for this latter complication has been called to question. Patients with other RET mutations are at higher risk of younger age onset phaeochromocytoma if they also possess other RET polymorphisms (L769L, S836S, G691S and S904S), but there are no similar data for patients with 609 mutations. We investigated the unusual phenotypic presentation in a family with MEN2A due to a C609Y mutation in RET. Sanger sequencing of the entire RET-coding region and exon–intron boundaries was performed. Five family members were C609Y mutation positive: 3/5 initially presented with phaeochromocytoma, but only 1/5 had MTC. The index case aged 73 years had no evidence of MTC, but presented with phaeochromocytoma. Family members also possessed the G691S and S904S RET polymorphisms. We illustrate a high penetrance of phaeochromocytoma and low penetrance of MTC in patients with a RET C609Y mutation and polymorphisms G691S and S904S. These data highlight the need for life-long screening for the complications of MEN2A in these patients and support the role for the screening of RET polymorphisms for the purposes of risk stratification.

Learning points:

  • C609Y RET mutations may be associated with a life-long risk of phaeochromocytoma indicating the importance of life-long screening for this condition in patients with MEN2A.

  • C609Y RET mutations may be associated with a lower risk of MTC than often quoted, questioning the need for early prophylactic thyroid surgery discussion at the age of 5 years.

  • There may be a role for the routine screening of RET polymorphisms, and this is greatly facilitated by the increasing ease of access to next-generation sequencing.

Full access

Shweta Birla, Viveka P Jyotsna, Rajiv Singla, Madhavi Tripathi, and Arundhati Sharma

Summary

Multiple endocrine neoplasia type 1 (MEN-1) is a rare autosomal-dominant disease characterized by tumors in endocrine and/or non endocrine organs due to mutations in MEN1 encoding a nuclear scaffold protein‘menin’ involved in regulation of different cellular activities. We report a novel 14 bp MEN1 deletion mutation in a 35-year-old female with history of recurrent epigastric pain, vomiting, loose stools and weight loss. On evaluation she was diagnosed to have multifocal gastro-duodenal gastrinoma with paraduodenal lymph nodes and solitary liver metastasis. She was also found to have primary hyperparathyroidism with bilateral inferior parathyroid adenoma. Pancreatico-duodenectomy with truncalvagotomy was performed. Four months later, radiofrequency ablation (RFA) of segment 4 of the liver was done followed by three and a half parathyroidectomy. MEN1 screening was carried out for the patient and her family members. MEN-1 sequencing in the patient revealed a heterozygous 14 bp exon 8 deletion. Evaluation for pathogenicity and protein structure prediction showed that the mutation led to a frameshift thereby causing premature termination resulting in a truncated protein. To conclude, a novel pathogenic MEN1 deletion mutation affecting its function was identified in a patient with hyperparathyroidism and gastrinoma. The report highlights the clinical consequences of the novel mutation and its impact on the structure and function of the protein. It also provides evidence for co-existence of pancreatic and duodenal gastrinomas in MEN1 syndrome. MEN1 testing provides important clues regarding etiology and therefore should be essentially undertaken in asymptomatic first degree relatives who could be potential carriers of the disease.

Learning points

  • Identification of a novel pathogenic MEN1 deletion mutation.

  • MEN1 mutation screening in patients with pituitary, parathyroid and pancreatic tumors, and their first degree relatives gives important clues about the etiology.

  • Pancreatic and duodenal gastrinomas may co-exist simultaneously in MEN1 syndrome.

Open access

Katsumi Taki, Takahiko Kogai, Junko Sakumoto, Takashi Namatame, and Akira Hishinuma

Summary

A de novo heterozygous inactivating mutation of calcium-sensing receptor (CASR) gene typically causes neonatal hyperparathyroidism (NHPT) with moderate hypercalcemia and hyperparathyroid bone disease. We present a case of asymptomatic hypocalciuric hypercalcemia with a de novo heterozygous mutation in CASR, S591C, which is primarily reported to be responsible for NHPT. A 54-year-old female was referred for investigation of asymptomatic hypercalcemia that was initially found in the 1980s but without a history of bone disease during the perinatal period. She had moderate hypercalcemia (12.4 mg/dl) and relative hypocalciuria (fractional extraction of calcium 1.07%) but normal intact parathyroid hormone and serum 1,25-dihydroxyvitamin D3. Pedigree analysis revealed that she carried a de novo heterozygous mutation of S591C, which she transmitted to an affected child with moderate hypercalcemia but not to other children, who had normal serum calcium levels. A de novo heterozygous CASR mutation that is responsible for NHPT may also present in individuals with asymptomatic hypocalciuric hypercalcemia. Caution is required when predicting course and outcome in a pedigree with CASR mutation, as well as incidental hypercalcemia, because of its variable phenotypes.

Learning points

  • The phenotype and severity of CASR mutations are thought to be dependent on genotypes.

  • We report an asymptomatic case of the de novo heterozygous S591C mutation in CASR, which has previously been reported as a responsible mutation of NHPT with bone diseases.

  • Variable phenotypes of CASR raise a cautionary note about predicting outcome by genotyping in a pedigree with CASR mutation.

Open access

Hanna Remde, Elke Kaminsky, Mathias Werner, and Marcus Quinkler

Summary

We report of a male patient aged 32 years who presented with primary hyperparathyroidism. Three parathyroid glands were resected. At the age of 46 years, nervus facialis irritation was noted, and an MRI scan incidentally revealed a non-functioning pituitary adenoma with affection of the chiasma opticum. The patient underwent transsphenoidal operation resulting in pituitary insufficiency postoperatively. At the same time, primary hyperparathyroidism reoccurred and a parathyroid adenoma located at the thymus was resected. The mother of the patient died early due to multiple tumors. The patient was suspected to have multiple endocrine neoplasia type 1 (MEN1) and genetic analysis was performed. In addition, on clinical examination, multiple exostoses were noticed and an additional genetic analysis was performed. His father was reported to have multiple osteochondromas too. MEN1 was diagnosed in the patient showing a novel heterozygote mutation c.2T>A in exon 2, codon 1 (start codon ATG>AAG;p.Met1?) of the MEN1 gene. In genetic mutational analysis of the EXT1 gene, another not yet known mutation c.1418-2A>C was found in intron 5 of the EXT1 gene (heterozygotic). In conclusion, we report novel mutations of the EXT1 and the MEN1 genes causing hereditary multiple osteochondromas and MEN1 in one patient.

Learning points

  • It is important to ask for the patient's family history in detail.

  • Patients with MEN1 are characterized by the occurrence of tumors in multiple endocrine tissues and nonendocrine tissues, most frequently parathyroid (95%), enteropancreatic neuroendocrine (50%), and anterior pituitary (40%) tissues.

  • Familiar MEN1 has a high degree of penetrance (80–95%) by the age over 50; however, combinations of the tumors may be different in members of the same family.

  • Patients with EXT1 gene mutations should be monitored for possible transformation of bone lesions into osteochondrosarcoma.

Open access

Kirun Gunganah, Ashley Grossman, and Maralyn Druce

Summary

A 22-year-old female student presented with a history of recurrent pancreatitis. The commonest causes of pancreatitis, including drugs, gallstones, corticosteroids, excess alcohol and hypertriglyceridaemia, were excluded. She was found to have an elevated serum calcium level that was considered to be the cause of her pancreatitis, with a detectable serum parathyroid hormone (PTH). An initial diagnosis of primary hyperparathyroidism was made. However, two neck explorations failed to reveal a parathyroid adenoma. She was referred to our unit three years later as her episodes of pancreatitis were becoming more frequent and her calcium level remained persistently elevated. Her investigations were as follows: elevated adjusted calcium level of 2.79 mmol/l (2.2–2.58), PTH level of 4.2 pmol/l (0.6–6.0), low 24 h urine calcium of 0.3 mmol/l and a urine calcium:creatinine ratio of <0.003. A clinical diagnosis of familial hypocalciuric hypercalcaemia (FHH) was made and confirmed on genetic testing that showed a c.1703 G>A mutation in the calcium-sensing receptor gene. Although the hypercalcaemia of FHH is usually without sequelae due to the generalised changes in calcium sensing, in the presence of this complication she was started on cinacalcet 30 mg daily. She had one further episode of pancreatitis with calcium levels ranging between 2.53 and 2.66 mmol/l. Her cinacalcet was gradually increased to 30 mg three times daily, maintaining her calcium levels in the range of 2.15–2.20 mmol/l. She has not had a further episode of pancreatitis for more than 2 years.

FHH is usually a benign condition with minimal complications from hypercalcaemia. Pancreatitis has been reported rarely, and no clear management strategy has been defined in these cases. Cinacalcet was successfully used in treating recurrent pancreatitis in a patient with FHH by maintaining calcium levels in the lower part of the reference range. Whether or not this is an effective long-term treatment remains yet to be seen.

Learning points

  • FHH is an important differential diagnosis for hypercalcaemia.

  • FHH can rarely cause pancreatitis.

  • No clear strategy is available to help in the management of patients with pancreatitis due to FHH.

  • Cinacalcet was effective in lowering serum calcium levels and reducing the frequency of pancreatitis in our patient with FHH.