A Case of Pseudohypoparathyroidism Type Ib Caused by Aberrant Methylation in the GNAS Complex Locus.
- Author:
Sung Jin JO
1
;
Eunhee HAN
;
Woori JANG
;
Hyojin CHAE
;
Yonggoo KIM
;
Gun Dong LEE
;
Won Kyoung CHO
;
Byung Kyu SUH
;
Myungshin KIM
Author Information
- Publication Type:Case Report
- Keywords: Pseudohypoparathyroidism; Methylation; GNAS complex locus; MLPA
- MeSH: Alleles; Epigenomics; GTP-Binding Proteins; Humans; Hyperphosphatemia; Hypocalcemia; Lower Extremity; Male; Methylation*; Motor Activity; Multiplex Polymerase Chain Reaction; Muscle Cramp; Parathyroid Hormone; Pseudohypoparathyroidism*
- From:Laboratory Medicine Online 2017;7(2):83-87
- CountryRepublic of Korea
- Language:English
- Abstract: Pseudohypoparathyroidism (PHP) is a rare disorder caused by genetic and epigenetic aberrations in the GNAS complex locus resulting in impaired expression of stimulatory G protein (Gsα). PHP type Ib (PHP-Ib) is characterized by hypocalcemia and hyperphosphatemia due to renal resistance to the parathyroid hormone, and is distinguished from PHP-Ia by the absence of osteodystrophic features. An 11-yr-old boy presented with poor oral intake and cramping lower limb pain after physical activity. Laboratory studies revealed hypocalcemia, hyperphosphatemia, and increased parathyroid hormone levels. The GNAS complex locus was evaluated using the methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA) assay. Gain of methylation in the NESP55 domain and loss of methylation in the antisense (AS) transcript, XL, and A/B domains in the maternal allele were observed. Consequently, we present a case of PHP-Ib diagnosed using MS-MLPA.
