Psoriasis is a chronic, inflammatory dermatosis that affects approximately 2% of the population, making it is one of the most common human skin diseases. Clinically, it is characterized by dry, reddish, thickened patches of the skin that are covered with silvery-gray scales. These patches are found on the scalp, elbows, knees, hands, feet, and/or lower back. These patches may be referred to as papules or plaques. They may be intensely itchy (pruritis) or sore. In some cases, patients may experience abnormalities affecting the fingernails, toenails, and the soft tissues inside the mouth. This disease has many clinical forms, vulgaris is the most common, and the pustular psoriasis is the less one. In this variety, the pustules are the predominant lessons, and it may be localized or generalized. Moreover, a substantial proportion of patients with psoriasis may develop a form of inflammatory arthritis known as psoriatic arthritis which contributes significantly to patient's disease burden with physical disability, pain and further reduction in quality of life. . The severity of psoriasis varies from case to case. Psoriasis may be classified as mild, moderate or severe depending upon the amount of skin involved and the effect on an individual's quality of life. The usual age of onset of psoriasis is between 15 and 30 years, although it can present at any age.
Psoriasis is a lifelong and progressive condition. There is currently no cure but various treatments can help to control the symptoms. These treatments include topical formulations, systemic therapies, phototherapies, and combination therapies.
The immunopathogenetic mechanisms in psoriasis development of this disease are not well known. It seems that psoriasis is a genetic disease of keratinocyte hyperproliferation mediated by T lymphocytes. A large number of triggering or aggravating environmental factors have been identified in subjects genetically predisposed to psoriasis such as bacterial (streptococci) and viral (HIV) infections, certain drugs, stress, alcoholism, and smoking.
It is well known that psoriasis is consistent with a multifactorial pattern of inheritance. However, family history is present in approximately one-third of cases. Psoriasis is genetically heterogeneous disease. The strongest genetic determinant of psoriasis identified to date lies within the class 1 region of the multiple histocompatibility locus antigen cluster on chromosome 6p21, particularly HLA-Cw6 allele which is highly associated with the disease.
Out of 84 patients (57 males, and 27 females, aged from 4 weeks to 58 years) with alopecia areata (AA), Mahmoud and Kamal (1998) found six patients with psoriases including three who had nail changes. Additionally, some patients were found to have a family history for psoriases.
[Mahmoud SF, Kamal AM. Nail changes in minimal alopecia areata. Gulf J Dermatol. 1998; 5 (1): 36-39.]
Al-Hamdi (2008) conducted an outpatient-based, cross sectional clinical study in the Dermatology Department of Basra Teaching Hospital, Basra, Iraq, from April 2004 to June 2007, where a total of 104 psoriatic children (59 females and 45 males; mean age 6.8 years) were analyzed. The study showed that scalp (20.2%), guttate (17.3%), and flexural psoriasis involving the napkin area (14.4%) or one or more of the body flexures, were the common modes of presentation reported in most cases. Many other atypical forms were also reported, and many aggravating factors were recognized.
Al Fouzan et al. (1994) studied childhood psoriasis and showed that the mean age of onset is 5.3 years. The most prevalent clinical variant was reported to be plaque psoriasis [83%] while guttate psoriasis came second. As for the most common site of lesions; extensor surfaces of the extremities came first [73%] followed by trunk and scalp. Nails were affected in 44% of the cases. [Al Fouzan AS, Nanda A. Childhood psoriasis in Kuwait: a prospective survey. Kuwait Med J. 1994; 26 (Supp.):45-7.]
Mahmoud (1998) studied the expression frequencies of the major histocompatibilty complex (MHC) in 26 Kuwaiti patients with psoriasis and 60 age, sex, and ethnic origin matched controls. The study revealed significantly increased expression of HLA-CW6, DQ2 and DQ7, while HLA-B7, DR5, and DR52 expression was significantly reduced in the cases versus the controls. [Mahmoud F. Association of major histocompatibility complex with psoriasis vulgaris in adult Kuwaitis. Med Princ Pract. 1998; 7(4):261-3.]
Nanda et al. (2000) studied 305 consecutive Kuwaiti children (60% females), under the age of 12-years, with psoriasis to understand the salient features, the course and prognosis and the HLA tissue typing of the disease in this ethnicity. Comparing to reports of childhood psoriatic patients from the Indian subcontinent, the Kuwaiti patients differed in terms of their female preponderance, and higher mean age of onset (5.7 years). Compared to reports of psoriasis from Western countries, the Kuwaiti patients differed in having an earlier age of onset, plaque psoriasis as the dominant clinical type (89%), more frequent nail involvement (32%), and greater frequency of pruritus. A family history of psoriasis was seen in 34% of the cases; higher than reports from the Indian subcontinent and lower than those reported in studies on Western populations. Fifty of these children, including 25 of those with a positive family history, were tissue typed for their HLA class I and II antigens. Overall, the patients showed a significant association with HLA-A3, Cw1, and DR7 antigens. The patients with a positive family history showed a significant positive association with HLA-DR8 and negative association with Cw4. Interestingly, contrary to previous reports, Nanda et al. (2000) did not find that an earlier age of onset of psoriatic symptoms led to a graver prognosis and a higher familial occurrence in their population.
El Shazly et al. (2003) conducted a descriptive study to determine the extent of psoriasis in Kuwait and the risk factors associated with it. The incidence and prevalence of psoriasis were calculated to be 0.11% and 0.45%, respectively. Case control study involving 200 patients and an equal number of controls found the risk factors for developing psoriasis to be male gander, smoking, sunbathing, the presence of arthritis or pharyngitis, liver impairment, and a positive family history for the condition. Progression of the disease was found to be positively influenced by alcohol consumption and more than five patches at initial presentation. Interestingly, a positive family history and treatment with PUVA were associated with a slower rate of progression. [El Shazly M, Al Mazeedi K, Hay RG, Makboul G. Epidemiology of psoriasis in Kuwait. Bull High Inst Public Health. 2003; 33(2):405-22.]
Out of 87 patients (33 Qatari, and 54 other nationalities; 73 males, and 14 females;76 adults, and 11 children; aged 2 to 56 years) with alopecia areata (AA), El-Tonsy et al. (1998) identified three patients (3.4%) with psoriases, and found four patients (4.6%) with a family history for the condition.
[El-Tonsy MH, Azadeh B, Kamal AM, El-Domyati MBM, Ibrahim FA. Auto antibodies and immunohistochemical studies in alopecia areata. Gulf J. Dermatol. Venerol. 1998; 5 (1): 40-45.]
Twenty five psoriasis Saudi patients were studied by Abanmi et al., (2005) to examine the association between HLA-C (Alanine-73 and Aspartate-9) and susceptibility to psoriasis. Using specific primers to detect nucleotide coding sequence for Ala-73 and Asp- 9 were applied for 25 PsV patients and 75 controls. The frequency of Asp-9 was significantly higher in PsV patients as compared to controls accounting for 84% and 61%, respectively. There was no significant difference in Ala-73 frequencies among PsV patients and controls. Patients and controls that were positive for Asp-9 were also positive for Ala-73, except one control.