title: Establishment of diagnosis by bisulfite-treated methylation-specific PCR method and analysis of clinical characteristics of pseudohypoparathyroidism type 1b.
abstract: Pathogenesis of pseudohypoparathyroidism type 1b (PHP-1b) is related to the loss of methylation at the GNAS exon A/B region, which is combined with epigenetic defects at other differentially methylated GNAS regions in most sporadic cases.  In this study, we established a method for evaluating the methylation status of a CpG island in exon A/B using a methylation-specific polymerase chain reaction (MSPCR).  We designed two primer pairs specific for the methylated and unmethylated alleles and evaluated the methylation status of GNAS exon A/B in samples from PHP-1b patients and normal controls.  We examined 20 Japanese patients and 20 normal controls, and one primer set was found to be appropriate for diagnosis.  Furthermore, we evaluated the clinical data of patients.  Weight and height of patients were not significantly different from the normal population.  Short stature (adult height ≤ 2SD) was observed in one patient and short metacarpals in two.  Obesity was observed in six patients, and no patient showed ectopic subcutaneous calcification.  Seven patients showed subclinical hypothyroidism because of resistance to thyroid stimulating hormone, but no patient had an abnormally low free thyroxine level, and none received oral thyroid hormone replacement.  For diagnosis of PHP-1b, only clinical data is not sufficient because a few PHP-1b patients show clinical features similar to PHP-1a, and hence, molecular biology techniques are required for correct diagnosis.  We concluded that MSPCR is applicable for rapid molecular diagnosis of PHP-1b.
authors.affiliation: Department of Pediatrics, Graduate School of Medicine, Chiba University, Chiba, Japan. kaori_kinoshita@hotmail.com
authors.forename: Kaori
authors.initials: K
authors.lastname: Kinoshita
authors.forename: Masanori
authors.initials: M
authors.lastname: Minagawa
authors.forename: Tomozumi
authors.initials: T
authors.lastname: Takatani
authors.forename: Rieko
authors.initials: R
authors.lastname: Takatani
authors.forename: Mika
authors.initials: M
authors.lastname: Ohashi
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Kohno
mesh_terms: D000293:Adolescent; D000328:Adult; D001483:Base Sequence; D002648:Child; D002675:Child, Preschool; D002864:Chromogranins; D018899:CpG Islands; D019175:DNA Methylation; D005091:Exons; D005260:Female; D019205:GTP-Binding Protein alpha Subunits, Gs / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007037:Hypothyroidism / Q000209:etiology; D007202:Indicators and Reagents / Q000737:chemistry*; D008297:Male; D008499:Medical Records; D008969:Molecular Sequence Data; D009765:Obesity / Q000209:etiology; D016133:Polymerase Chain Reaction / Q000379:methods*; D011401:Promoter Regions, Genetic; D011547:Pseudohypoparathyroidism / Q000097:blood / Q000175:diagnosis* / Q000378:metabolism / Q000503:physiopathology*; D012189:Retrospective Studies; D013447:Sulfites / Q000737:chemistry*
chemical_list: D002864:Chromogranins; D007202:Indicators and Reagents; D013447:Sulfites; C406732:GNAS protein, human; D019205:GTP-Binding Protein alpha Subunits, Gs; C042345:hydrogen sulfite