Dataset Information

GNAS, PDE4D, and PRKAR1A Mutations and GNAS Methylation Changes Are Not a Common Cause of Isolated Early-Onset Severe Obesity Among Finnish Children.

ABSTRACT: Context: Pseudohypoparathyroidism type Ia (PHP1A) is caused by inactivating mutations involving GNAS exons 1-13, encoding the alpha-subunit of the stimulatory G protein (Gs?). Particularly PHP1A, but also other disorders involving the Gs?-cAMP-signaling pathway, have been associated with early-onset obesity. Thus, patients with mutations in the genes encoding PDE4D and PRKAR1A can also be obese. Furthermore, epigenetic GNAS changes, as in pseudohypoparathyroidism type Ib (PHP1B), can lead to excessive weight. Objective: Search for genetic variants in GNAS, PDE4D, and PRKAR1A and for methylation alterations at the GNAS locus in Finnish subjects with isolated severe obesity before age 10 years. Methods: Next generation sequencing to identify pathogenic variants in the coding exons of GNAS, PDE4D, and PRKAR1A; Multiplex Ligation-dependent Probe Amplification (MLPA) and methylation-sensitive MLPA (MS-MLPA) to search for deletions in GNAS and STX16, and for epigenetic changes at the four differentially methylated regions (DMR) within GNAS. Results: Among the 88 subjects (median age 13.8 years, median body mass index Z-score +3.9), we identified one rare heterozygous missense variant of uncertain significance in the XL exon of GNAS in a single patient. We did not identify clearly pathogenic variants in PDE4D and PRKAR1A, and no GNAS methylation changes were detected by MS-MLPA. Conclusions: Our results suggest that coding GNAS mutations or methylation changes at the GNAS DMRs, or coding mutations in PDE4D and PRKAR1A are not common causes of isolated childhood obesity in Finland.

SUBMITTER: Loid P

PROVIDER: S-EPMC7155765 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

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GNAS, PDE4D, and PRKAR1A Mutations and GNAS Methylation Changes Are Not a Common Cause of Isolated Early-Onset Severe Obesity Among Finnish Children.

Loid Petra P Pekkinen Minna M Reyes Monica M Mustila Taina T Viljakainen Heli H Jüppner Harald H Mäkitie Outi O

Frontiers in pediatrics 20200407

Context: Pseudohypoparathyroidism type Ia (PHP1A) is caused by inactivating mutations involving GNAS exons 1-13, encoding the alpha-subunit of the stimulatory G protein (Gsα). Particularly PHP1A, but also other disorders involving the Gsα-cAMP-signaling pathway, have been associated with early-onset obesity. Thus, patients with mutations in the genes encoding PDE4D and PRKAR1A can also be obese. Furthermore, epigenetic GNAS changes, as in pseudohypoparathyroidism type Ib (PH ...[more]

PMID: 32318528

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Project description:Pseudohypoparathyroidism type 1A (PHP1A), pseudoPHP (PPHP), and PHP type 1B (PHP1B) are caused by maternal and paternal GNAS mutations and abnormal methylation at maternal GNAS promoter(s), respectively. Adult PHP1A patients are reportedly obese and short, whereas most PPHP patients are born small. In addition to parathyroid hormone (PTH) resistance, PHP1A and PHP1B patients may display early-onset obesity. Because early-onset and severe obesity and short stature are daily burdens for PHP1A patients, we aimed at improving knowledge on the contribution of the GNAS transcripts to fetal and postnatal growth and fat storage. Through an international collaboration, we collected growth and weight data from birth until adulthood for 306 PHP1A/PPHP and 220 PHP1B patients. PHP1A/PPHP patients were smaller at birth than healthy controls, especially PPHP (length Z-score: PHP1A -1.1?±?1.8; PPHP -3.0?±?1.5). Short stature is observed in 64% and 59% of adult PHP1A and PPHP patients. PHP1B patients displayed early postnatal overgrowth (height Z-score at 1 year: 2.2?±?1.3 and 1.3?±?1.5 in autosomal dominant and sporadic PHP1B) followed by a gradual decrease in growth velocity resulting in normal adult height (Z-score for both: -0.4?±?1.1). Early-onset obesity characterizes GNAS alterations and is associated with significant overweight and obesity in adults (bodey mass index [BMI] Z-score: 1.4?±?2.6, 2.1?±?2.0, and 1.4?±?1.9 in PPHP, PHP1A, and PHP1B, respectively), indicating that reduced Gs? expression is a contributing factor. The growth impairment in PHP1A/PPHP may be due to Gs? haploinsufficiency in the growth plates; the paternal XL?s transcript likely contributes to prenatal growth; for all disease variants, a reduced pubertal growth spurt may be due to accelerated growth plate closure. Consequently, early diagnosis and close follow-up is needed in patients with GNAS defects to screen and intervene in case of early-onset obesity and decreased growth velocity. © 2018 The Authors. Journal of Bone and Mineral Research Published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research (ASBMR).

Project description:ObjectiveInactivating heterozygous mutations in the GCK gene are a common cause of MODY and result in mild fasting hyperglycaemia, which does not require treatment. We aimed to identify the frequency, clinical and molecular features of GCK mutations in a Turkish paediatric cohort.Design and patientsFifty-four unrelated probands were selected based on the following criteria: age of diagnosis ≤17 years, family history of diabetes in at least two generations, anti-GAD/ICA negative, BMI<95.p and follow-up with diet, oral antidiabetic drug or low-dose insulin treatment (≤0·5U/kg/d). A MODY probability score (www.diabetesgenes.org) was calculated and 21 patients with a score ≥75%, HbA1c levels ≤7·5% (58·5 mmol/mol) and fasting blood glucose (FBG) levels 99-145 mg/dl (5·5-8·0 mmol/l) were selected for Sanger sequencing of the GCK gene. Targeted next-generation sequencing for all known monogenic diabetes genes was undertaken for any patient without a GCK gene mutation.ResultsGCK gene mutations (pathogenic or likely pathogenic variants) and a novel intronic variant of uncertain significance (c.208 + 3A>T) were identified in 13/54 probands (24%). Twelve of these patients had a MODY probability score ≥75%. FBG level and 2-h glucose level in OGTT were 123 ± 14 mg/dl (6·8 ± 0·7 mmol/l) (107-157 mg/dl) and 181 ± 30 mg/dl (10·1 ± 1·6 mmol/l) (136-247 mg/dl), respectively. Average of glucose increment in OGTT was 58 ± 27 mg/dl (3·2 ± 1·5 mmol/l) (19-120 mg/dl), and mean HbA1c level was 6·5 ± 0·5% (47·5 ± 5·5 mmol/mol) (5·9-7·6%). Five novel missense mutations were identified (p.F123S, p.L58P, p.G246A, p.F419C, and p.S151C). Two patients treated with low-dose insulin before the molecular analysis were able to stop treatment.ConclusionsApproximately 1 in 4 MODY cases in this Turkish paediatric cohort have a GCK mutation. Selection of patients for GCK gene analysis using the MODY probability score was an effective way of identifying most (11/12) patients with a GCK mutation.

Dataset Information

GNAS, PDE4D, and PRKAR1A Mutations and GNAS Methylation Changes Are Not a Common Cause of Isolated Early-Onset Severe Obesity Among Finnish Children.

Publications

<i>GNAS, PDE4D</i>, and <i>PRKAR1A</i> Mutations and <i>GNAS</i> Methylation Changes Are Not a Common Cause of Isolated Early-Onset Severe Obesity Among Finnish Children.

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