Allele-specific transcriptional activity of the variable number of tandem repeats of the inducible nitric oxide synthase gene is associated with idiopathic achalasia.
BACKGROUND
Polymorphisms of genes involved in the regulation of the immune response are risk factors for achalasia, but their contribution to disease pathogenesis is unknown. Nitric oxide is involved both in immune function and inhibitory neurotransmission.


OBJECTIVE
The objective of this article is to assess the association and the functional relevance of the CCTTT-inducible nitric oxide synthase (NOS2) gene promoter polymorphism in achalasia.


METHODS
Genomic DNA was isolated from 181 achalasia patients and 220 controls. Genotyping of the (CCTTT)n repeats was performed by PCR and capillary electrophoresis, and data analyzed by considering the frequency of the different alleles. HT29 cells were transfected with iNOS luciferase promoter-reporter plasmids containing different (CCTTT)n.


RESULTS
The alleles' distribution ranged from 7 to 18, with a peak frequency at 12 repeats. Analysis of the allele frequencies revealed that individuals carrying 10 and 13 CCTTT repeats were respectively less and more frequent in achalasia (OR 0.5, 95% CI 0.3-0.5 and OR 1.6, 95% CI 1-2.4, allp< 0.05). Long repeats were also significantly associated with an earlier onset of the disease (OR 1.69, 95% CI 1.13-2.53,p= 0.01). Transfection experiments revealed a similar allele-specific iNOS transcriptional activity.


CONCLUSIONS
The functional polymorphism (CCTTT) ofNOS2promoter is associated with achalasia, likely by an allele-specific modulation of nitric oxide production.
Gastroenterology Unit, Department of Clinical Medicine and Surgery University Federico II, Naples, Italy.
Giovanni
G
Sarnelli
Department of Biochemistry and Medical Biotechnology, University Federico II, Naples, Italy.
Michela
M
Grosso
Gastroenterology Unit, Department of Clinical Medicine and Surgery University Federico II, Naples, Italy.
Ilaria
I
Palumbo
Gastroenterology Unit, Department of Clinical Medicine and Surgery University Federico II, Naples, Italy.
Marcella
M
Pesce
Gastroenterology Unit, Department of Clinical Medicine and Surgery University Federico II, Naples, Italy.
Alessandra
A
D'Alessandro
Imperial College-St Mary's Hospital, Department of Academic Surgery, London, UK.
Giovanni
G
Zaninotto
Unit of Gastroenterology SOD2, Azienda Ospedaliera Universitaria, Careggi, Firenze, Italy.
Vito
V
Annese
Department of Biochemistry and Medical Biotechnology, University Federico II, Naples, Italy.
Raffaella
R
Petruzzelli
Department of Biochemistry and Medical Biotechnology, University Federico II, Naples, Italy.
Paola
P
Izzo
Department of Biochemistry and Medical Biotechnology, University Federico II, Naples, Italy.
Rossana
R
Sepulveres
Department of Public Health, University Federico II, Naples, Italy.
Dario
D
Bruzzese
Department of Physiology and Pharmacology, "La Sapienza" University of Rome, Italy.
Giuseppe
G
Esposito
Gastroenterology Unit, Department of Clinical Medicine and Surgery University Federico II, Naples, Italy.
Rosario
R
Cuomo
(CCTTT)n pentanucleotide; Idiopathic achalasia; genetic polymorphism; iNOS; nitric oxide