Antonietta Amedei

Two Novel Mutations at Exon 8 of the Sequestosome 1 (SQSTM1) Gene in an Italian Series of Patients Affected by Paget's Disease of Bone (PDB)†

PDB is genetically heterogeneous. Mutations of the sequestosome1 gene have been reported in sporadic and familial forms of Pagets in patients of French Canadian and British descent. Mutational analyses in different ethnic groups are needed to accurately investigate hereditary diseases. We describe two novel mutations of sequestosome1 in 62 Italian sporadic patients, confirming the role of the encoded protein in this disorder.

A patient with MEN1-associated hyperparathyroidism, responsive to cinacalcet

Background A 30-year-old woman with suspected multiple endocrine neoplasia type 1 (MEN1) was referred to our center in 2001 with primary hyperparathyroidism caused by a multiglandular parathyroid adenoma. The patient also had hyperprolactinemia caused by an anterior pituitary macroadenoma. The patient underwent a parathyroidectomy with autotransplantation of parathyroid fragments into the nondominant forearm, resulting in resolution of the primary hyperparathyroidism. MEN1 was confirmed by analysis of the MEN1 gene, which revealed a 1555insG frameshift mutation. In 2006 serum calcium and parathyroid hormone (PTH) levels were again found to be high.Investigations After parathyroidectomy in 2001, the patient underwent regular measurements of PTH levels from both forearms, of serum calcium, prolactin and phosphate levels, and of urinary calcium and phosphate levels. When serum calcium and PTH levels were found to be elevated in 2006, circulating PTH levels were similar in both forearms. Ultrasound scan and technetium-99m-labeled hexakis-2-methoxyisobutylisonitrile (99mTc MIBI) scintigraphy evidenced a metabolically active parathyroid nodule in the neck.Diagnosis Local recurrence of a parathyroid adenoma associated with MEN1.Management Because the patient refused a further operation, we decided to initiate pharmacological treatment with cinacalcet. After 1 month of therapy, serum calcium and PTH levels returned to normal. The patient has now been closely monitored for 1 year. During this time calcium and PTH levels remained normal, morphologically the parathyroid nodular lesion remained unchanged and cinacalcet was well tolerated without the occurrence of adverse events. Cinacalcet could represent an important pharmacological intervention in MEN1-associated primary hyperparathyroidism before surgery and in postsurgical recurrences.

Segregation of a M404V mutation of the p62/sequestosome 1 (p62/SQSTM1) gene with polyostotic Paget's disease of bone in an Italian family

Mutations of the p62/Sequestosome 1 gene (p62/SQSTM1) account for both sporadic and familial forms of Pagets disease of bone (PDB). We originally described a methionine→valine substitution at codon 404 (M404V) of exon 8, in the ubiquitin protein-binding domain of p62/SQSTM1 gene in an Italian PDB patient. The collection of data from the patients pedigree provided evidence for a familial form of PDB. Extension of the genetic analysis to other relatives in this family demonstrated segregation of the M404V mutation with the polyostotic PDB phenotype and provided the identification of six asymptomatic gene carriers. DNA for mutational analysis of the exon 8 coding sequence was obtained from 22 subjects, 4 PDB patients and 18 clinically unaffected members. Of the five clinically ascertained affected members of the family, four possessed the M404V mutation and exhibited the polyostotic form of PDB, except one patient with a single X-ray-assessed skeletal localization and one with a polyostotic disease who had died several years before the DNA analysis. By both reconstitution and mutational analysis of the pedigree, six unaffected subjects were shown to bear the M404V mutation, representing potential asymptomatic gene carriers whose circulating levels of alkaline phosphatase were recently assessed as still within the normal range. Taken together, these results support a genotype–phenotype correlation between the M404V mutation in the p62/SQSTM1 gene and a polyostotic form of PDB in this family. The high penetrance of the PDB trait in this family together with the study of the asymptomatic gene carriers will allow us to confirm the proposed genotype–phenotype correlation and to evaluate the potential use of mutational analysis of the p62/SQSTM1 gene in the early detection of relatives at risk for PDB.