Giovanni Brenci

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Monozygotic twins are the best witnesses of the existence of a hereditary biological time, because they would not be identical if they had not also inherited the times of appearance and duration of their common hereditary information. The authors gave the name "chronogenetics" to this branch of genetics which concerns the temporal dimension of the gene and(More)
The condition of low birth weight is compared in twins and in singletons in terms of birth weight distributions and with respect to factors such as the incidence of stillbirths, length of gestation, maternal age, parity, and legitimacy. In the light of demographic, biological, and developmental considerations, it is concluded that low birth weight in twins(More)
The observation of a balanic hypospadia with chordee associated with a renal malformation in both of identical twins is reported. Monozygosity of twins was demonstrated with the study of ABO, MNS, HLA and RH factor systems. Urography, performed in both twins, showed a specular crossed renal ectopia with fusion. Abdominal ultrasounds, Chest-X-ray and barium(More)
A study of sleep and dream characteristics has been carried out by questionnaire on a sample of 77 MZ and 76 DZ same-sex twin pairs of two age groups, 6-8 and 16-18 years. Genetic effects could not be detected in the younger age group and appeared to be rather limited in the older one, possibly as a result of the limited variability of the considered(More)
A chronogenetic analysis of caries has been carried out in a sample of 100 twin pairs (27 MZ, 64 DZ, 9 UZ) aged 3-8 years, taking into account the number of decayed teeth and the intensity and severity of caries. Heritability estimates, calculated for each of the various parameters considered, support the hypothesis of a genetic control of the time of onset(More)
A case is reported of a 14-year old male MZ twin pair, with only one partner affected by situs viscerum inversus, whereby the condition is termed situs viscerum specularis. The high degree of mirror imaging is seen as an abnormal variation of the biological time of the cleavage giving rise to MZ twinning. Electrocardiographic findings are presented and the(More)
A concordance study of 6 infectious diseases of childhood has been carried out in a sample of 656 twin pairs classified by sex and zygosity. A new approach is proposed to estimate the respective influence of heredity and of common environment. The estimates thus obtained range from 86% hereditary component in the case of measles to 100% environmental(More)
A new approach is proposed in twin research based on the study of twins who, though reared together, have subsequently lived apart for a period of at least five years. With respect to the more powerful study of twins reared apart, the twins living apart test has the advantages of being more realistic and affording easier access to sufficiently large(More)