Toluene diisocyanate (TDI) is the most common cause of occupational asthma in western countries. The aim of this study was to investigate whether genetic factors are involved in toluene diisocyanate-induced asthma.We studied the frequency of human leucocyte antigen (HLA) class II genetic markers in three groups of subjects: 1) subjects with TDI-induced asthma (n=30); 2) exposed subjects with no history of TDI-induced asthma (n=12); and 3) normal subjects not exposed to TDI (n=126). Venous blood samples were collected from the three groups and the polymorphic second exon of DQA and DQB genes was amplified by the polymerase chain reaction (PCR) method.Evaluation of HLA class II gene products in TDI-induced asthma cases showed a positive association with HLA-DQB1*0503 and a negative association with HLA-DQB1*0501 alleles, which differed at residue 57 for a single amino acid, i.e. aspartic acid in DQB1*0503 and valine in DQB1*0501. No significant difference was found in the distribution of DQA1 alleles between asthmatics and controls.Our results confirm the hypothesis that HLA-DQB1*0503 has a role in conferring susceptibility to TDI-induced asthma and that residue 57 of HLA-DQB1 is a potentially critical location.

Epidemiological and genetic variables in clefts were analyzed during the years 1978-1986 in a case-control study of congenital malformations in the Emilia Romagna region of northern Italy. Among 150,168 newborns, 200 cases of cleft were detected, yielding a prevalence of 1.33 per 1,000. These clefts consisted of 112 (0.075%) cases of cleft lip with or without cleft palate (CL +/- P) and 88 cases (0.058%) of cleft palate (CP). Coexisting abnormalities were found in 32% of cases. The heritability coefficient of CL +/- P was 0.84. No cluster in time or space could be demonstrated. Epilepsy was the only maternal risk factor found to be correlated with clefts. A predominance of males was found among CL +/- P cases.

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