RESUMEN
Primary immunodeficiency disorders [PID] are a heterogeneous group of diseases, characterized by an increased susceptibility to infections. To determine the frequency of PID in south of Tunisia to collect information on clinical experience with these disorders. Over a period of 16 years [1995 - 2010], primary immunodeficiency was confirmed in 51 patients [31 boys and 20 girls]. The immunological investigation included a study of specific and/or non specific humoral and cellular immunity. These 51 patients belonged to 47 families among which 37 were consanguine [80%]. The immunological investigations revealed a cellular or combined immunodeficiency in 21 cases, with a majority of ataxia-telangiectasia syndromes [11 cases], HLA class II deficiency [9 cases]. A predominant antibody defect was found in 3 patients and a chronic granulomatous disease in seven cases. Deaths occurred So far in 19 patients [37 %]. PID are relatively frequent in Tunisia, probably because of the high rate of consanguinity among the general population. The distribution of the different groups of primary immunodeficiencies is characterized by high frequency of ataxia - telangiectasia and HLA class II deficiency