Abstract

MAIA, José António Ribeiro et al. Zygosity determination: From Peeters´ questionnaire to DNA microsatelites. Rev. Port. Cien. Desp. [online]. 2007, vol.7, n.2, pp.147-155. ISSN 1645-0523.

This study had the purpose of testing the validity of an indirect method to assess zygosity in twin studies in the Portuguese population. The sample included 96 twins (45 monozygotic and dizygotic twin groups), of both sexes, from 6 to 12 yrs old, and their biological mothers, summing 141 subjects. Two methods were used to determine zygosity: (1) Indirectly, through Peeters et al. (1998) questionnaire filled out by the mothers; (2) Directly, through blood sampling of each twin member, and their DNA was analysed in the laboratory. Proportion of correct classification of twins as monozygotic or dizygotic through Peeters et al. (1998) Questionnaire was 97,8%. The Qui-Square test was highly significant (c²=41.053, p<0.0001), and it was reinforced by McNemar test (p<0.0001). The results allow us to conclude that Peeters et al. (1998) Questionnaire shows transcultural validity to assess zygosity in twin studies in the Portuguese Population.

Keywords : gemelarity; twins; questionnaire; DNA; validity.

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