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Genetic testing in familial isolated hyperparathyroidism: unexpected results and their implications
1Department of Diabetes and Endocrinology, Princess Alexandra Hospital, Ipswich Rd, Woolloongabba 4102, Qld, Australia.
Journal of Medical Genetics
|February 27, 2004
Summary
Genetic testing for familial isolated hyperparathyroidism (FIHP) should prioritize MEN1 and CASR mutations, regardless of calcium excretion. HRPT2 testing is reserved for HPT-JT phenotypes, highlighting the need for further FIHP gene discovery.
Area of Science:
- Endocrinology
- Genetics
- Molecular Biology
Background:
- Familial hyperparathyroidism (FHP) comprises several genetic syndromes, including MEN1, MEN2A, HPT-JT, FHH, and FIHP.
- Differentiating these syndromes is crucial for patient and family management, yet challenging.
- Genetic testing aids diagnosis and family screening but requires cost-effective application.
Purpose of the Study:
- To investigate the genetic basis of familial isolated hyperparathyroidism (FIHP) in unrelated subjects.
- To determine the prevalence of MEN1, CASR, and HRPT2 mutations in FIHP phenotypes.
- To guide the rational use of genetic testing for FHP syndromes.
Main Methods:
- Genotyping for MEN1, CASR, and HRPT2 mutations was performed on 22 unrelated subjects with FIHP phenotypes.
- Phenotypic data, including urinary calcium excretion and gland involvement, were analyzed in relation to genotype.
- Subjects with mutations were assessed for multiglandular involvement and compared to typical FHH phenotypes.
Main Results:
- MEN1 mutations were identified in 5 (23%) subjects, and CASR mutations in 4 (18%) subjects.
- No HRPT2 mutations were found in the studied FIHP cohort.
- All subjects with MEN1 or CASR mutations exhibited multiglandular hyperparathyroidism; CASR mutation carriers did not present with the typical FHH phenotype.
Conclusions:
- MEN1 and CASR genotyping are recommended for patients with multiglandular FIHP, irrespective of urinary calcium levels.
- HRPT2 genotyping should be reserved for suspected HPT-JT syndrome cases.
- Further research is necessary to identify additional genes implicated in FIHP.