Biomedical subjects
Publications and source records attributed to R Vlietinck.
The twin model was used to assess the validity of an electromyographically recorded, masseter muscle reflex by measuring the sensitivity and specificity. Results were satisfying, implying that in future studies this reflex could be used to calculate heritability estimates between monozygotic and dizygotic twins.
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It is generally impossible to collect blood or to culture tissue from a macerated stillborn fetus. Accurate genotyping of such a fetus may, however, be critical for the diagnosis of genetic diseases and appropriate genetic counseling. In the East Flanders Prospective Twin Study, placental tissue of twin and triplet sets, in some of which one or both members were stillborn and macerated, has been stored at -20 degrees C. Of all these fetuses, sex and zygosity could be determined accurately on the placental deoxyribonucleic acid. We tested the possibility of nongenetic changes in deoxyribonucleic acid that result from maceration or tissue degradation over time in storage on placental samples from monochorionic twins in which only one member was stillborn and macerated. The deoxyribonucleic acid variants in these monozygotic twins were identical whether or not either cotwin was macerated. Thus deoxyribonucleic acid variants can be determined accurately on the placental tissue of macerated fetuses, even after prolonged freezing.
Based on Dutch twin incidence figures since the beginning of the current century, evidence is provided in support of the idea that the DZ unlike/like sexed ratio has gradually shifted (since 1900) from unity to less than unity. Opposing conclusions with regard to the justification of the use of Weingberg's differential rule are very probably correct in themselves but could depend on country and period of birth of the twin sample used. Furthermore, the fast drop and subsequent rise in DZ twinning rate between about 1963 and 1990 can very likely for the greater part be ascribed to a parallel shift in maternal age.
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In Lisala, Equateur province, Zaire, 25 patients from 21 pedigrees were identified with human T-lymphotropic virus type 1 (HTLV-1) associated tropical spastic paraparesis (TSP). In the 10 (48%) pedigrees with additional genuine TSP cases established mainly by history, seven of 10 patients' mothers, no fathers or spouses, one of 59 surviving offspring, five of 105 siblings, and six other close blood relatives had TSP. A child may develop TSP before its mother. Three familial cases were in paternal relatives only. In total, 39 cases (11 men, 28 women) were identified in this population of about 50,000. Half were in the Mundunga minority of less than or equal to 10% (p less than 0.001). The data suggest maternal transmission of HTLV-1 and enhanced TSP susceptibility in those infected due to familial, probably genetic factors.
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