Academic journal article Genetic Counseling

Mode of Inheritance in Systemic Lupus Erythematosus in Saudi Multiplex Families

Academic journal article Genetic Counseling

Mode of Inheritance in Systemic Lupus Erythematosus in Saudi Multiplex Families

Article excerpt

Summary: Mode of inheritance in systemic lupus erythematosus in Saudi multiplex families: Systemic lupus erythematosus (SLE) is a an autoimmune disease causing inflammation and injury of multiple organs like joints, skin, kidneys, eyes, central nervous system, heart. The etiology of SLE remains unknown. However; genetic component significantly contributes to the etiology of SLE. Familial SLE patients were defined as a family with more than one sibling diagnosed with SLE. The objective of the study is to describe the clinical features of the familial SLE and analyze the family pedigrees. Twenty-five individuals with SLE belonging to seven Saudi families were included. Three-generation pedigree was taken from the candidate families. The mean age at onset of the disease was 84.5 months (range: 18-144) while the mean age at diagnosis was 90.6 months (range: 24- 144) and the mean duration of follow up was 48.5 months (range: 7-108). The proportion of girls was predominant (78 %). Malar rash, arthritis and nephritis were the more frequent features. Sixteen patients had renal lesions, 10 of them had class VI nephritis according WHO classification. Five of the seven families are consanguineous reflecting the high percentage of consanguinity in our population. As many other autoimmune diseases, multifactorial is the most common form of inheritance. In the current study, the suggested mode of inheritance is autosomal recessive assuming Mendelian inheritance of single gene disorder.

Key-words: Familial systemic Lupus Erythematosus- Family pedigree - Autosomal recessive inheritance- Saudi families.

INTRODUCTION

Systemic lupus erythematosus (SLE, MIM 152700) is a complex multisystem autoimmune disease characterized by the production of a variety of antibodies against nuclear components that causes inflammation and injury of multiple organs (3). Although SLE is a disease of young women, the onset can range from infancy to advanced age. The prevalence varies with race, ethnicity and socioeconomic status. Although no recent data are available, the incidence among children younger than 15 years of age has been estimated at 0.5 to 0.6 per 100,000. It constitutes up to 10% of the new diagnosis of systemic rheumatic diseases in children (5, 8).

The etiology of SLE is still unknown. However; genetic and environmental factors including ultraviolet light, drugs and viral infection may contribute in the etiology of SLE. Studies of multiplex families showed that 5-12% of patients have a relative affected by SLE. Many approaches have been used with partial success to delineate the genetic determinants of SLE, including analysis based on candidate genes, genome-wide linkage studies, and family based classical linkage studies (3;. First, familial clustering indicated that SLE has a significant genetic component with sibling risk ratio (? = 20). Secondly, association studies have shown that certain HLA antigens have strong association with SLE like HLA-DR2,-DR3,-B7,-B18,-DQA1,-DQB1,-DQ3, and DR7 (9, 12). Thirdly, several loci were found to have highly significant linkage (LOD>3) by genome wide linkage studies. More than 20 other loci showing suggestive linkage to SLE (LOD=1.9) were also identified (Table I) (6, 13).

In the present study, we describe the clinical phenotype and the extended family pedigrees of 7 Saudi Lupus multiplex families to decide the mode and inheritance.

METHODS AND SUBJECTS

Patients with SLE undergoing treatment in Pediatric Rheumatology Clinic at King Faisal Specialist Hospital and Research Center (KFSHRC) in Riyadh are included in this study. AU included patients fulfilled the definition of SLE using the revised 1982 American College of Rheumatology classification criteria. Drug-induced lupus, mixed connective tissue disease and overlap syndrome were excluded from the study. Familial SLE patients were defined as a family with more than one sibling diagnosed with SLE. The frequency of various variables is recorded. …

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