Acetylator phenotype in Iraqi patients with atopic dermatitis
Published Web Locationhttps://doi.org/10.5070/D32t24z87g
Acetylator phenotype in Iraqi patients with atopic dermatitis
1. Department of Pharmacology, College of Medicine, University of Baghdad, Baghdad, Iraq. firstname.lastname@example.org 2. Department
of Dermatology, College of Medicine, University of Baghdad, Baghdad, Iraq
Rafid A Najim1, Makram M Al-Waiz2, Rafi AM Al-Razzuqi1
Dermatology Online Journal 12 (7): 1
Atopic dermatitis (AD) is a common multifactorial disease which has an itchy, recurrent, flexural and symmetrical eczematous eruption. There are reports that indicate that AD is associated with a predominantly slow acetylator status. This study was designed to determine the acetylator status in children with AD and compare it to a matched group of normal children. The study included 36 AD patients diagnosed clinically and 42 healthy controls. A detailed history was taken from the parents of each patient and disease severity was assessed using the Hanifin-Rajka scoring system. After an overnight fast, each control subject and patient received a single oral dose of 50 mg of dapsone; a blood sample was collected after 3 hours and plasma separated for determination of dapsone and monoacetyldapsone by HPLC. The frequency of slow acetylators in the control group was 69.4 percent and the frequency of rapid acetylators was 30.6 percent. The frequency of slow acetylators among AD patients was 72.2 percent and the frequency of rapid acetylators was 27.80 percent. There were no statistically significant differences between the control and AD patients groups. There was an association in AD patients between the acetylator status and family history of allergy as well as the severity assessed by the Hanifin- Rajka scoring system. Although slow acetylators had lesions predominantly on the limbs, the distribution of lesions on the skin of rapid acetylators favored the face and neck. Although a slow acetylator status does not predispose to AD, it is associated with a different severity and distribution of the disease.
Atopy is a term referring to a group of patients who have a personal or a familial history of one or more of the following diseases: hay fever, asthma, eczema, and very dry skin . Atopic dermatitis (AD) is a common multifactorial disease that commonly manifests as an itchy, recurrent, flexural, and symmetrical eczematous eruption. Its frequency increases during childhood but it classically resolves by age 30 .
There are two functional arylamine N-acetyltransferases in human cells, NAT1 and NAT2, which are coded by different genes . The enzyme found in the liver and epidermis, NAT2, follows a bimodal distribution pattern . This cytosolic phase-II conjugation enzyme calalyzes N-acetylation of polymorphic substrates, such as aromatic amines or hydralazine . The human NAT2 locus is highly polymorphic with 30 known alleles . The genetic polymorphism in N-acetylation causes interindividual variations in the metabolism of various drugs, precarcinogens, and other xenobiotics . The human population can be divided, based on NAT2 activity, as rapid or slow acetylators . It has been shown that slow acetylation phenotype influences the development of allergic diseases [6, 7, 8, 9]. However a more recent report failed to find such an association .
The present paper examines the acetylator phenotype status in Iraqi AD children. The Iraqi population, as well as other Middle Eastern populations, is characterized by a predominance of slow acetylators . Therefore it is interesting to examine this problem in a predominantly slow acetylator population. In addition the possible association of the acetylator state on different aspects of the disease was also examined.
Patients and methods
Approval to conduct this study was granted by the appropriate local ethical committee. The nature of the trial was explained to each subject and the consent of parents of each subject was obtained. Excluded from this study were individuals with glucose-6-phosphate dehydrogenase deficiency or allergy to sulfonamides
We included 36 patients, 21 males and 15 females, with atopic dermatitis in the study. Their ages ranged from 8 to 11 years (mean 9.66 ± 0.91 years). Patients were recruited from the outpatient clinic of the Department of Dermatology in Baghdad Teaching Hospital/ Medical City. All patients were diagnosed by specialist dermatologists. A full history was taken from the parents by completing a questionnaire form that was designed by Hanifin- Rajka  to evaluate the sensitivity and the specificity of the disease using a scoring system.
The control group comprised 42 healthy children, 27 males and 15 females, who were recruited from two primary schools. Permission was obtained from their parents and the school's authorities. Their ages ranged from 8 to 11 years (mean 9.63 ± 0.59 years).
After an overnight fast, each subject received a single oral 50 mg dose of dapsone (AL-NILE Company for Pharmaceuticals and Chemical Industries, Cairo, Egypt). Drinking caffeinated beverages was not allowed throughout the study period. A blood sample (5 ml) was obtained 3 hours after drug intake by venipuncture that was added to a 10 ml polyethylene tube containing 50 µl of heparin (Heparin Leo 5000 IU/ml, Leo Pharmaceutical Products, Denmark). Plasma was separated within 1 hour after collection by centrifugation (3000 x g. for 10 min). The samples were subsequently stored frozen at -20° C pending analysis.
A rapid, simple, one-stage protein precipitation method for the estimation of plasma DDS and MADDS concentrations by high performance liquid chromatography (HPLC)  was described in a previous study .
Statistical analyses were done using SPSS version 10 computer software. Results were presented as mean ± S.D. Differences between groups were assessed by Fisher's Exact test. An estimate was considered to be statistically significant if p value was <0.05. Linear correlation was tested by simple regression analysis .
There were 42 subjects, 15 females and 27 males. Their ages ranged from 8 to 11 years (mean 9.63 ± 0.59 SD). According to the acetylator status, they were as follows:
Slow acetylators were those whose acetylation ratio was less or equal to 0.30. They were 29 subjects (12 females and 17 males) representing 69.4 percent of the group. Their mean age was 9.44 ± 0.79 years. The plasma concentration of DDS ranged from 0.31-2.84 µg/ml (mean 0.87 ± 0.23 µg/ml) and the plasma concentration of MADDS ranged from 0.09 -1.01 µg/ml (mean 0.45 ± 0.38 µg/ml). (Tables 1 and 2)
Rapid acetylators were those whose acetylation ratio was more than 0.30. They were 13 subjects (3 females and 10 males) representing 30.6 percent. Their mean age was 9.82 ± 0.73 years. The plasma concentration of DDS ranged from 0.57-1.64 µg/ml (mean 0.64 ± 0.27 µg/ml) and the plasma concentration of MADDS ranged from 0.21 to 1.12 µg/ml (mean 0.53 ± 0.22 µg/ml). (Tables 1 and 2)
There were 36 patients (15 females and 21 males). Their ages ranged from 8 to 11 years (mean 9.66 ± 0.91 SD). According to the acetylation ratio, they were as follows:
A. Slow acetylators were those whose acetylation ratio was less or equal to 0.30. They were 26 patients (10 females and 16 males) representing 72.2 percent. Their mean age was 9.76 ± 0.84 years). The plasma concentration of DDS ranged from 0.45 -2.18 µg/ml (mean 0.82 ± 0.31 µg/ml) and the plasma concentration of MADDS ranged from 0.08 to 0.64 µg/ml (mean 0.36 ± 0.17 µg/ml). (Tables 1 and 2)
Rapid acetylators were those whose acetylation ratio was more than 0.30. There were 10 patients (5 females and 5 males) representing 27.8 percent. Their mean age was 9.55 ± 0.98 years. The plasma concentration of DDS ranged from 0.65 to 1.91 µg/ml (mean 0.94 ± 0.37 µg/ml) and the plasma concentration of MADDS ranged from 0.20 to 0.92 µg/ml (mean 0.59 ± 0.18 SD). (Tables 1 and 2)
No significant difference was found between the frequency distribution of acetylation phenotype in AD patients and healthy subjects.
Acetylation in AD patients with and without a history of allergy
Patients with history of allergy represented 77.8 percent (28 out of 36 patients, 14 males and 14 females). Those without a history of allergy were 22.2 percent (8 out of 36 patients)(Table 3). When these allergic patients were subdivided according to acetylation phenotype, the allergic slow acetylators were 84.6 percent (22 out of 26 allergic patients). When they were subdivided according to the origin of allergy (personal, familial or from both origins), it was found that the allergic slow acetylators with familial predisposing factors represented 86.3 percent (19 out of 22 allergic slow acetylators). Slow acetylators represented 71.4 percent of the allergic patients (19 out of 28 allergic patients) (Table 3). This distinction was not found in allergic rapid acetylators. There were an equal number of non-allergic slow and rapid acetylators, 4 subjects. A significant association was found between the history of allergy as a variable and the acetylation ratio (p < 0.05).
Acetylation in AD patients and Hanifin-Rajka scoring system
The Hanifin-Rajka scoring system evaluates the sensitivity and the specificity of atopic dermatitis . Accordingly, the patients were divided into those with a score equal to or more than 50 points and those with score of less than 50 points (Table 4). Patients with scores equal to or more than 50 points were severely involved and aggressive, long-term therapy was required to produce remission . They represented 30.6 percent (11 out of 36 patients, 7 males and 4 females). All of them were slow acetylators. The association was significant (p <0.05) (Table 4).
Acetylation in AD patients and eczema sites
The sites of eczematous lesions in AD patients showed some correlation to the acetylation phenotype (Table 5). Patients with eczematous lesions located predominantly on the limbs (elbow, knee joints, hands and feet) were mostly slow acetylators. They represented 76.9 percent (20 out of 26 slow acetylator patients, 11 males and 9 females). Patients with eczematous lesions located mainly on the face and neck were mainly rapid acetylators. They represented 60 percent (6 out of 10 rapid acetylator patients, 3 males and 3 females). A significant association was found between the sites of eczematous lesions in AD patients and the acetylation ratio (p <0.05) (Table 5).
The results show that the control group composed of 42 healthy children were predominantly slow acetylators (69.4 %). In a previous report we found that among a control group composed of 67 healthy adults (age range 18-48 years) the slow acetylators were 71.6 percent . The difference in the percentage of slow acetylators was not statistically significant. This confirms that age does not affect the acetylation speed. This result agrees with the results of Philip et al. . Both failed to show any effect of age on acetylation status. However, it does not agree with a report from Hungary that found that acetylation ratio decreased with older age .
Results revealed that 72.2 percent of the AD patients were slow acetylators and 27.8 percent were rapid acetylators. These acetylation ratios were not significantly different from the age-matched control groups. This agrees with the report by Brocvielle et al.  who were unable to detect any association between the acetylation status phenotype or genotype and AD. However in that report AD patients were all adults with ages ranging between 22 to 59 years, in contrast to the population of this study, children (8-11 years). The Brocvielle et al.  study was carried out in a population of predominantly rapid acetylators (60 %) in contrast to the present study population of predominantly slow acetylators.
Some of our results contrast with results of other previous studies. According to Gawronska-Szklar et al. , there was a predominance of slow acetylators among allergic patients. Two other studies confirmed this association [6, 7]. The contrast may be explained by the fact that the population of this study as well as the population of Brocviell et al.  consisted exclusively of patients with atopic dermatitis. The three other studies included other allergic diseases such as allergic rhinitis asthma and food allergy.
The association between acetylator status and the clinical picture of AD has not been noted previously. Thus when the history of allergy in atopic dermatitis is considered, the allergic patients represent 77.8 percent while the allergic slow acetylators represent 84.6 percent. If the familial history of allergy is considered, the patients with this factor represent 71.4 percent of allergic patients while the allergic slow acetylators with this factor represent 86.3 percent of allergic patients. These findings confirm that in AD patients in our population a familial history of allergy is associated with the slow acetylator trait.
When the severity of the disease and acetylation is assessed using the Hanifin-Rajka scoring system, the results show that the severe cases (those with scores equal to or more than 50 points) are all slow acetylators and none are rapid acetylators. More severe disease correlates with a lower acetylation ratio. Therefore, we could conclude that although the acetylation status did not predispose to AD, a slow acetylator status in an AD patient together with a familial history of allergy, would correlate with more severe disease.
In addition, acetylation status correlates with the distribution of the eczematous lesions; slow acetylators exhibit dermatitis mainly on the limbs whereas rapid acetylators show dermatitis mainly on the face and neck.
Therefore, although AD is not associated with acetylator status, slow acetylator AD patients may be liable to have more severe disease that is located on the limbs.
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