1. Investigations carried out on twins and the families have revealed that within the major group of brain gliomatosis and glioblastomatosis there is a minor group (up to day) of accumulated familiar clinical cases.

Topographically, they are tumours localized in the region of the ventricular germinative centres, that is to say, in the background of the brain (they are not cortical gliomas!). They depend on the disturbances and inhibition of the matricial cellules on the ventricular wall towards the cerebral cortex. Histologically they are considered as dysplasias with a blastomatosis character, that is to say, neoplastological productions on an heredogenetic basis the cause of which lies in histological disorders, disontoge-netic, and therefore, congenital.

2. A work hypothesis is settled and established according to wich 2 factors at least are necessary for the formation of a tumour: a local one, hereditary: the neuroglial dyplasia in the region of the ventricular germinal centres with a tendency to tumours degeneration; and another or several general factors dependent on endogenous and exogenous influences, which on account of a disturbance of the general constitution (for example, hormone mechanisms of puberty, of the premenopause and of the beginning of the involution) which would allow the tumour to develop starting with the tumours genetic disposition.

3. At the present time it is not known whether the genesis causing this neuroglial dyplasia and the concomitant malformations of other organs, sonsists in the mutation of a gen, since so far the gen is ignored as well the pleotropic effet of the action developed by the gen.

4. The fact, that within the major group, in the majority of cases evidently not hereditary of gliomatosis and glioblastomatosis, there should appear a minor group, hereditary, must be considered, within the general investigation of the neoplasias, as a further proof that the essential thing of the hereditary predisposition to the development of tumours, must be considered as a specific local factor.

5. The attention is called to the possible existence, within the astrocytomes of a small hereditary group of familial cases.

6. The casuistry so far known has been enlarged with 20 cases (discordant) of twins and 6 observation in families which were compiled at the Neurological Clinic of Miinster Westfalen University.

A holoacardius from a monozygotic, monochorionic twin pregnancy of 36 weeks is described. Trisomy-18 was diagnosed in the viable female cotwin. Computerized tomographic, radiologic, and ultrasonographic procedures were applied to the acardiac. Its three-vessel umbilical cord was velamentously attached to the single placenta. Grossly malformed and poorly developed craniofacial structures, absence of neck and upper extremities, sirenomelic lower extremity, absence of heart, and development of only a few skeletal elements were prominent features. A review of selected world literature emphasizes the limits of the estimates dealing with the total number of reported cases and the incidence of acardii.

Eleven reports of osteopetrosis due to dominant genes (table 1) establish in a firm basis the existence of such a genetic variant. By personal interview with all radiologists and orthopedists of Pòrto Alegre and larger Rio Grande do Sul cities, an estimate of 1: 100,000 was obtained for the frequency of osteopetrosis in this Brazilian State.

The genetic and environmental contributions to physical aging (hair graying, balding, presbyopia) and longevity (age at death) were examined by within-pair comparison in monozygotic (MZ) and dizygotic (DZ) twins in later adulthood. Physical aging was investigated on 135 pairs of adult twins aged over 50. Hair graying and hair loss (baldness) showed significantly higher rates of concordance in the MZ twins than in the DZ twins. The intrapair difference of the degree of hair graying was negligible in 79%, slight in 15% and striking in 5% among the MZ pairs; while negligible in 40%, slight in 50% and striking in 10% among the DZ pairs. The intrapair difference of the degree of hair loss was negligible in 92%, slight in 8% (and striking in none) among the MZ pairs; while negligible in 69%, slight in 25% and striking in 6% among the DZ pairs. The age at onset of presbyopia showed a slightly higher rate of concordance in the MZ than in the DZ pairs. Longevity (age at death) was surveyed on 184 pairs of twins who died at over 40 years of age. The intrapair difference of longevity was 6.65 ± 5.6 years (maximum 18.0; minimum 0.04) in the MZ pairs, and 8.66 ± 7.2 years (maximum 18.6; minimum 2.9) in the DZ pairs. The MZ pairs showed a slightly smaller within-pair difference of longevity than the DZ pairs.

Important works on the question of hereditary influence on the occurrence of cancer with application of twin series are those by v. Verschuer and Kober (cf. Spranger and v. Verschuer, 1964), Jarvik and Falek (1961) and Harvald and Hauge (1963). Their findings are by and large consistent with most earlier reports (Schull et al, 1959) and indicate that hereditary factors do not seem to influence the development of cancer as such, but possibly play a role in the localization of the tumor. In view of the fact that (except for Harvald and Hauge's investigation) the twin series studied have been comparatively small and yielded statistically unreliable numbers of cancer of specific site, it seems to be of value to extend the data by reporting findings from the Swedish Twin Registry, comprising about 11000 unselected twin pairs.

The present paper reports mortality and morbidity in cancer of different site as well as concordance rates for MZ and DZ twins. In addition, the influence of smoking habits on cancer development has been analyzed, as this environmental factor is known to be associated with certain forms of cancer, particularly lung cancer (Smoking and Health, 1964).

Cancer data have been obtained from two sources, the Swedish Cancer Registry and the Registry of Causes of Death.

The Swedish Twin Registry in the present report comprises 10 945 twin pairs, and covers, in principle, all same-sexed twins born in Sweden in 1886-1925, and still living in the country as unbroken pairs at the time of compilation (1961). A detailed report of the compilation procedures and demographic data is given by Cederlöf (1966).

Within the Finnish Twin Cohort of like-sexed adult twin pairs, a subgroup of pairs separated at an early age has been identified. In 165 pairs, both cotwins responded to questionnaires in 1975 and 1979. An environmental dissimilarity score was formed which consists of items on whether the twins had lived after separation in the same community, attended the same school, were on the same grade at school, how often the cotwins met, how often they met common friends and relatives and whether they attended the same clubs etc, or not. To validate the zygosity diagnosis obtained by questionnaire in 1975, those pairs whose zygosity was unknown as well as those with the least contact after separation were contacted for blood sampling (11 bloodgroups). Of 15 pairs with no zygosity diagnosis, 10 responded (1 no address,2 abroad,2 refused). Six pairs were classified MZ and 4 DZ. In 12 MZ and 8 DZ pairs undergoing bloodgroup determination, the classification of only one pair changed from DZ to MZ. The following intraclass correlations for height and weight were found:

A study of 100 MZ and 67 DZ twin pairs aged 18 to 25 years has shown a highly significant genetic contribution to the following measurements: standing and sitting height; height on tragus; arm length; biacromial, biiliac, and bitrochanteric diameter; weight; circumference of thigh and of upper arm relaxed and contracted; and head length and breadth. The twins were brought up together and of the same socioeconomical, geographical, ethnical, and cultural origin. Zygosity diagnosis was based on 22 to 26 blood groups. The means of the measurements were smaller in MZ than in DZ twins, some of them significantly so. The intraclass correlation coefficients of the MZ cotwins were all significant and greater than those of the DZ cotwins. In families of same geographical origin, sib-sib correlations were somewhat smaller than those of the DZ cotwins, but for the three diameters of the body the order was reversed.

Twinning rates were studied in Swedes, Åland Islanders, Finns, Germans, and Dutch during years of starvation when death rates were two to three times higher than average. In contrast to the situation among some animals, this study suggests that nutrition above a certain threshold is unimportant for human reproduction, including twinning. The twinning rates for these different populations display marked temporal differences, but low values in the twinning rate are not consistently associated with periods of epidemics, famine, or similar nutritional stress. After years of privation and/or separation of spouses, a rapid “catch-up effect” can often be seen in the twinning rates, as well as marriage and birth rates. Psychoendocrine factors and interparental immunological conditions that may be involved in this phenomenon are discussed.

A case-control study was conducted to evaluate the association between maternal age and parity and dizygotic (DZ) and monozygotic (MZ) twinning, respectively. Mothers of all twins born alive in Denmark in 1984 or 1985 were included into the study as cases, and a random sample of mothers of singletons were controls. Data on maternal age at delivery and number of previous births were collected from the Danish Medical Birth Register. By means of logistic regression analysis, a significant and positive association was found betwen maternal age and DZ twinning, and a significant and negative association between parity and MZ twinning. No association was found for parity and DZ twinning, nor for maternal age and MZ twinning. The study suggests that human MZ twinning has predictors too, as has DZ twinning. The finding has implications for zygosity classification in future twin research.

1) An increase of hemoglobin A2 over 3% is regarded as one of the two fundamental manifestations of the commonest thalassemic mutant in the heterozygous condition i.e. thalassemia minima or typical microcytemia (here indicated as MA), while the other element is represented by the characteristic ensemble of the morphological and functional alterations of the erythrocytes. This assumption is based on the fact that the infrequent cases of sharp dissociation between the two elements i.e.i) red cells normality with A2 above 3 % (mA), and ii) microcytemia with normal levels of A2 (Ma). run in families and cannot be easily explained as a partial manifestation of a typical microcytemic gene.

2) The unilocal origin of the Ma variant seems to be well proved by the segregations from 5 Ma × ma (normal) matings where 10 Ma and 9 ma children have been observed. Moreover this variant has been detected among the relatives of a carrier of Hb H, born from a Ma × ma mating. This is in agreement with other recently published reports and strongly suggests that the relationship between Hb H and atypical microcytemia (with low A2) has a precise etiological significance.

3) The unilocal origin of the mA variant (normocytic thalassemia?) is at the moment less firmly established. However a family is described (mating mA × MA) where the father and one child show the same mA phenotype; moreover one other child is affected by constitutional microcytic anemia (Th. media). This finding supports the observations of Silvestroni and Bianco, who have already reported that a number of patients with intermediate thalassemic syndromes are born from mA × MA matings.

4) At the moment no data exist which enable to decide whether the different thalassemias are mutations of the same or of different loci; however if they shall be shown to be allelic, the hypothesis must be kept in mind that the Thalassemia locus is a complex locus with more than one mutation sides, responsible for different but correlated aspects of the phenotype (red cell structure and A2 level).

5) The new hemoglobin B2, is described which has been recently identified by Kunkel. Ceppellini, Dunn and Firsheim (unpublished data). Reasons are given for regarding B2 as the product of a mutation at the locus which is responsable for the synthesis of A2 (locus Hb2), The relationship of allelism between A2 and B2 is a proof of the genetic heterogeneity of the hemoglobin of the normal adult and may be taken as a model suggesting the genetic heterogeneity of hemoglobin A, notwithstanding its apparent chemical omogeneity.

6) It is concluded that the conditions generally indicated as Thalassemias represent a genetically heterogeneous group, which have nonetheless to do with related metabolic processes. It is therefore suggested that the term Thalassemia may be mantained for indicating all hereditary defects which directly interfere with hemoglobinogenesis although not producing a specific abnormal hemoglobin.

Birth weight data for 356 pairs of newborn twins of known zygosity and placentation are presented. The combined weights of dizygotic twins are heavier than those of monozygotic twins. The significance of this finding is discussed in relation to the association between increased maternal height and dizygotic twinning.

The objective of this study was to assess the childhood growth of twin children in terms of the effects of intrauterine growth retardation (IUGR) and discordancy at birth on the incidence and severity of stunting and discordancy in current height and weight. The study was part of a cross-sectional field project conducted at the Annual Twins Days Festival in Twinsburg. Ohio, USA, during 1990, 1991, and 1993, and including all twin children between 2 and 12 years of age. Mothers of twins were interviewed regarding their children's birthweights and gestational age; the twin children were measured for their current heights and weights. The study population included 990 twin children, including 555 boys and 435 girls, of which there were 254 boy pairs and 194 girl pairs. Birthweight for gestational age and current weight and height were each converted into Z-scores and characterized as severe (Z-score <−2,0), or moderate IUGR or stunting (Z-score > −2.0 and < −1.2). For the present study discordancy in birthweight, and current height and weight was calculated for like-gender twin pairs. Only twin children with severe IUGR at birth showed an increased risk of stunting in their current height or weight, and this risk was only for moderate, not severe, stunting. Boy twins with severe IUGR at birth were at increased risk of moderate stunting in their current weight (OR 2.67, 95% CI 1.55, 4.58, P = 0.002), while girl twins with severe IUGR at birth were at increased risk of moderate stunting in their current height (OR 4,09, 95% CI 1.49, 10.99, p = 0.003). Among like-gender twin pairs, there were no differences in mean or categories of birthweight or current weight discordancy, but boy twin pairs did show a significantly greater proportion of current weight discordancy compared to girl twin pairs (p = 0.005). Overall, there was a significant tendency for differences in height and weight between like-gender twin pairs to disappear over time, with the effect being greater for boy twin pairs. We conclude from these findings that twin children tend to overcome growth retardation and discordancy present at birth, and although children who had severe IUGR or discordancy at birth were more likely to have some residual moderate stunting or discordancy in height or weight, they still tended to be within normal values for their gender and current age.

Population studies on human twinning are scarce in Argentina. In order to analyze frequencies and certain maternal and neonatal variables related to twin births, we studied a series of 69.678 consecutive newborns with 500 g of weight and over, which occurred at a public hospital in the province Buenos Aires, during 14 years (1982-1995). The frequency of twin births (10 per 1000 deliveries) and sex ratio were similar to other studies reported in Caucasian population. Maternal age and order of gravity/parity were positively correlated with twinning rates, more markedly so in dissimilar sex-pairs. Stillbirths and neonatal deaths were more frequent in twins than in singletons, but less frequent when comparing groups of same weight. Congenital malformations were not found to be significantly more frequent in twins than in the total newborn population. However, their occurrence, predominantly in like-sexed pairs and the concordance for defect type in doubly affected same-sex pairs, suggests that monozygotic twinning carries an increased risk for malformation.

Background: Maternal nutrition has a strong influence on singleton and twin birthweight. This study evaluated the association between twin birthweight and maternal pregravid body mass index (BMI), weight gain, and cravings and aversions. Information was also obtained regarding sources of nutrition advice and advised versus actual weight gain.

Methods: This study is based on data from interviews with 928 mothers of twins. Univariate analysis included comparisons by source of nutritional advice, birthweight categories, and categories of cravings and aversions. Multiple logistic regression was used to formulate models for mean twin birthweights > 1,500 g and > 2,500 g.

Results: Mothers who received their nutrition advice from a registered dietitian had the highest weight gains and the lowest proportion of birthweights < 1,500 g. For mean twin birthweight > 2,500 g, the final model included prematurity, pregravid BMI, and weight gain; for birthweights > 1,500 g, the model additionally included maternal age and aversions.

Conclusions: Maternal pregravid BMI and gestational weight gain were shown to be important factors influencing twin birthweight. Nutrition advice, particularly from a registered dietitian, may be vital in assuring adequate weight gain, and therefore better birthweights, for these high-risk pregnancies.

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 biological implications of the condition are discussed.

Based on the outcome of 21 triplet pregnancies from Antoine Béclère Hospital, early diagnosis in the major requirement for improving rates of fetal survival in multiple pregnancies. The outcome was better in mothers with spontaneous ovulation than in those with induced ovulations. Elective cesarean section in proposed.

In order to examine the chronologic changes in genetic variance and heritability of anthropometric characteristics of Chinese infants in Taiwan, a total of 521 pairs of same-sexed twin neonates given birth in four major general teaching hospitals in Taipei City were studied. Based on the placental pattern and 12 red blood cell antigens, 428 MZ and 93 DZ twin pairs were identified and followed up to the age of one year. There was no significant genetic variance for all anthropometric characteristics adjusted for sex and gestational week before the age of six months. After adjusting for sex and gestational week, a significant genetic variance was observed at the age of six months, with heritability values of 0.51 (weight), 0.63 (head circumference), 0.77 (chest circumference), and 0.53 (arm circumference), as well as at one year, although with considerably lower heritability values. This implies that growth is dynamically determined by both genetic and environmental factors during infancy.

Seventy-nine pairs of same-sex twins were examined at the age of three years at a municipal clinic and their mothers were interviewed to assess the twins' current and past behaviours. The zygosity was determined after the interview by fingerprints and/or bloodtyping in the majority of cases. The following significant differences in concordance between monozygotic and dizygotic twins were found: 1) fear of strangers during observation at the clinic; 2) marked fear of strangers in the first year of life; 3) whether or not the child was startled by sudden noises during infancy; 4) whether or not the child was able to sleep alone at three years without a parent sitting nearby; 5) susceptibility to motion sickness; 6) nocturnal enuresis; 7) short attention span or restlessness during the test.