COMPARATIVE DIAGNOSES OF TWIN ZYGOSITY BY SSLP VARIANT ANALYSIS, QUESTIONNAIRE, AND DERMATOGLYPHIC ANALYSIS

Zygosity diagnosis has been performed in 79 pairs of twins using three methods. Simple sequence repeat length polymorphism (SSLP) analysis a llows an efficient classification (MZ or DZ) with only a few markers f ollowing a simplified technique of extraction and amplification. A met hod based on a full questionnaire completed by parents about twin simi larity correctly classifies 97.46% of the pairs; 92.41% are correctly classified using only four questions as suggested by logistic regressi on analysis. The third method, using dermatoglyphic analyses, correctl y classifies 86.76% of pairs. To lower the cost of DNA diagnosis we st ress the possibility of limiting its use to pairs with scores in the o verlap area between MZ and DZ twins with a validated questionnaire.