Mutation of the signal peptide-encoding region of the preproparathyroid hormone gene in familial isolated hypoparathyroidism

Andrew Arnold, Susan A. Horst, Thomas J. Gardella, Hisamitsu Baba, Michael A. Levine, Henry M. Kronenberg

    Research output: Contribution to journalArticlepeer-review

    Abstract

    Preproparathyroid hormone (preproPTH) gene mutation has been proposed as a cause of familial isolated hypoparathyroidism (FIH). We cloned the preproPTH alleles of a patient with autosomal dominant FIH and sequenced the coding regions, 5′ flanking regions, and splice junctions. The putatively abnormal (based on previous linkage studies) allele differed from the other allele's normal sequence at only one nucleotide. This T to C point mutation changes the codon for position 18 of the 31 amino acid prepro sequence from cysteine to arginine, disrupting the hydrophobic core of the signal sequence. Because the hydrophobic core is required by secreted proteins for efficient translocation across the endoplasmic reticulum, the mutant protein is likely to be inefficiently processed. Indeed, in vitro studies demonstrated dramatically impaired processing of the mutant preproPTH to proPTH. In summary, we observed a point mutation in the signal peptide-encoding region of a preproPTH gene in one FIH kindred and demonstrated a functional defect caused by the mutation. Mutation of the signal sequence constitutes a novel pathophysiologic mechanism in man, and further study may yield important insights both into this form of hormone deficiency and into the role of signal sequences in human physiology.

    Original languageEnglish (US)
    Pages (from-to)1084-1087
    Number of pages4
    JournalJournal of Clinical Investigation
    Volume86
    Issue number4
    StatePublished - Oct 1990

    Keywords

    • Leader
    • Point mutation
    • PTH

    ASJC Scopus subject areas

    • Medicine(all)

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