Yasuo Mashio

Genetic and epigenetic states of the GNAS complex in pseudohypoparathyroidism type Ib using methylation-specific multiplex ligation-dependent probe amplification assay

CONTEXT Pseudohypoparathyroidism type Ib (PHP-Ib) is a rare disorder resulting from genetic and epigenetic aberrations in the GNAS complex. PHP-Ib, usually defined by renal resistance to parathyroid hormone, is due to a maternal loss of GNAS exon A/B methylation and leads to decreased expression of the stimulatory G protein α (Gsα) in specific tissues. OBJECTIVE To clarify the usefulness of methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA), we evaluated genetic and epigenetic changes of the GNAS locus in Japanese PHP-Ib patients. DESIGN Retrospective case series. PATIENTS We studied 13 subjects with PHP-Ib (three families with eight affected members and one unaffected member and four sporadic cases). MEASUREMENTS The methylation status of GNAS differentially methylated regions (DMRs) was evaluated using MS-MLPA. The main outcome measure was the presence of deletion mutations in the GNAS locus and STX16, which were assessed using MLPA. RESULTS In all familial PHP-Ib cases, a ~3 kb deletion of STX16 and demethylation of the A/B domain were identified. In contrast, no deletion was detected throughout the entire GNAS locus region in the sporadic cases. Broad methylation abnormalities were observed in the GNAS DMRs. CONCLUSIONS MS-MLPA allows for precise and rapid analysis of the methylation status in GNAS DMRs as well as the detection of microdeletion mutations in PHP-Ib. Results confirm the previous findings in this disorder and demonstrate that this method is valuable for the genetic evaluation and visualizing the methylation status. The MS-MLPA assay is a useful tool that may facilitate making the molecular diagnosis of PHP-Ib.

CK (creatine kinase)-linked immunoglobulins observed in patients with autoimmune thyroid diseases

CK (creatine kinase)-linked immunoglobulins observed in patients with autoimmune thyroid diseases Yasuo MASHIO 1), Mutsuo BENIKO 2), Akira MATSUDA 2),Shigeki KOIZUMI 2) Kumiko MATSUYA 3),Hiroaki MIZUMOTO 2),Akemi IKOTA 2), Haruhiko KUNITA 3) 1)Department of Internal Medicine, Kin-ikvo Sapporo Kita-ku Hospital 2)Department of Internal Medicine , Kin-ikyo Chuou Hospital 3)Department of Internal Medicine , Kin-ikyo Sapporo Nishi-ku Hospital