Objective: Myotonic dystrophy (DM) is a monogenic disorder. It is caused by expansion of a cytosine-thymineguanine triplet in the DMPK gene which encodes for myotonic dystrophy protein kinase (DMPK). Methods: A 24-year-old man with DM and the DMPK mutation presented with elevated adrenocorticotropic hormone (ACTH) levels twice (152 and 185 pg/mL; normal value is 10 to 52 pg/mL) with normal cortisol levels (134.6 and 113.0 ng/mL, or 371.3 and 311.7 nmol/L; normal values are 67 to 226 ng/mL or 184.8 to 623.5 nmol/L). ACTH, corticotropin-releasing hormone (CRH) and insulin tolerance test (ITT) demonstrated normal cortisol response to ACTH and partial response to CRH and ITT tests, and ACTH hyperresponse to CRH and ITT. We suspected ACTH and/or ACTH receptor (ACTHR) mutations and evaluated the genetic profile for pro-opiomelanocortin (POMC), melanocortin 2 receptor (MC2R) and follicle-stimulating hormone receptor (FSHR) genes. Results: No mutations were found in either the MC2R or FSHR genes. The patient was heterozygous for the c.614A>G mutation corresponding to a p.53D>G substitution with a glycine instead of an aspartate in position 53 in POMC gene. This mutation was outside the sequence for ACTH (which spans amino acids 138 to 176) but was included in the part originating the N-terminal peptide of pro-opiomelanocortin (also called pro-γ-melanocyte stimulating hormone) which spans amino acids 27 to 102 and is involved in the regulation of adrenal steroidogenesis. Conclusion: The pathologic expansion of the cytosine-thymine-guanine triplet repeat in the 3' noncoding region of DMPK could explain the hyperresponse of ACTH typical of DM. The mutation of pro-γ-melanocyte-stimulating hormone could be associated with the abnormal response of cortisol, compatible with a partial adrenal insufficiency. Other studies are necessary to demonstrate this hypothesis. © 2019 AACE.

Cantara, S., Chiofalo, F., Ciuoli, C., Marzocchi, C., Dotti, M., Maccora, C., et al. (2019). Rare POMC Mutation in a Patient With Myotonic Dystrophy Type 1 and Adrenocorticotropin Hyperresponse to Corticotropin-Releasing Hormone. AACE CLINICAL CASE REPORTS, 5(2), e132-e137 [10.4158/ACCR-2018-0382].

Rare POMC Mutation in a Patient With Myotonic Dystrophy Type 1 and Adrenocorticotropin Hyperresponse to Corticotropin-Releasing Hormone

Silvia Cantara
;
Francesco Chiofalo;Cristina Ciuoli;Carlotta Marzocchi;Maria Teresa Dotti;MACCORA, CARLA;Maria Grazia Castagna;Fabio Giannini
2019-01-01

Abstract

Objective: Myotonic dystrophy (DM) is a monogenic disorder. It is caused by expansion of a cytosine-thymineguanine triplet in the DMPK gene which encodes for myotonic dystrophy protein kinase (DMPK). Methods: A 24-year-old man with DM and the DMPK mutation presented with elevated adrenocorticotropic hormone (ACTH) levels twice (152 and 185 pg/mL; normal value is 10 to 52 pg/mL) with normal cortisol levels (134.6 and 113.0 ng/mL, or 371.3 and 311.7 nmol/L; normal values are 67 to 226 ng/mL or 184.8 to 623.5 nmol/L). ACTH, corticotropin-releasing hormone (CRH) and insulin tolerance test (ITT) demonstrated normal cortisol response to ACTH and partial response to CRH and ITT tests, and ACTH hyperresponse to CRH and ITT. We suspected ACTH and/or ACTH receptor (ACTHR) mutations and evaluated the genetic profile for pro-opiomelanocortin (POMC), melanocortin 2 receptor (MC2R) and follicle-stimulating hormone receptor (FSHR) genes. Results: No mutations were found in either the MC2R or FSHR genes. The patient was heterozygous for the c.614A>G mutation corresponding to a p.53D>G substitution with a glycine instead of an aspartate in position 53 in POMC gene. This mutation was outside the sequence for ACTH (which spans amino acids 138 to 176) but was included in the part originating the N-terminal peptide of pro-opiomelanocortin (also called pro-γ-melanocyte stimulating hormone) which spans amino acids 27 to 102 and is involved in the regulation of adrenal steroidogenesis. Conclusion: The pathologic expansion of the cytosine-thymine-guanine triplet repeat in the 3' noncoding region of DMPK could explain the hyperresponse of ACTH typical of DM. The mutation of pro-γ-melanocyte-stimulating hormone could be associated with the abnormal response of cortisol, compatible with a partial adrenal insufficiency. Other studies are necessary to demonstrate this hypothesis. © 2019 AACE.
2019
Cantara, S., Chiofalo, F., Ciuoli, C., Marzocchi, C., Dotti, M., Maccora, C., et al. (2019). Rare POMC Mutation in a Patient With Myotonic Dystrophy Type 1 and Adrenocorticotropin Hyperresponse to Corticotropin-Releasing Hormone. AACE CLINICAL CASE REPORTS, 5(2), e132-e137 [10.4158/ACCR-2018-0382].
File in questo prodotto:
File Dimensione Formato  
Rare POMC mutation.pdf

non disponibili

Tipologia: PDF editoriale
Licenza: NON PUBBLICO - Accesso privato/ristretto
Dimensione 1.03 MB
Formato Adobe PDF
1.03 MB Adobe PDF   Visualizza/Apri   Richiedi una copia

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11365/1071722