It has been recently shown that the human requirement for exogenous ascorbic acid and the disease, scurvy, are the result of a typical genetic disease syndrome caused by a defect on the gene controlling the synthesis of the enzyme protein, L-gulonolactone oxidase. The lack of this active enzyme in the human liver prevents Man from producing his own ascorbic acid; a synthesis which is regularly carried out by nearly all other mammals. This genetic disease has been named, Hypoascorbemia. This new concept of the genetic etiology of scurvy gives a much broader outlook and opens perspectives which were lacking in the previous fifty year old nutritional or trace “vitamin C” hypothesis. “Correction” of this genetic defect in Man is now possible since the availability of ascorbic acid in large quantities. By “correction” is meant the long-term administration of ascorbic acid in the large amounts the human liver would be synthesizing had this genetic defect not occurred. The mammals have long used the increased liver biosynthesis of ascorbic acid, under stress, to maintain homeostasis. The genetic defect prevents Humans from utilizing this important mammalian biochemical protective mechanism. Supplying exogenous ascorbic acid at the proper high dosage for full “correction” is merely duplicating a normal mammalian reaction. The medical implications of the full “correction” of this genetic disease are discussed and speculations on the effects of “correction” in the rheumatoid diseases, cardiovascular conditions, strokes, cancer and the aging process are extrapolated from the meager data already in the medical literature. This paper is mainly a plea for more thought along the medical possibilities opened by this new concept and for more clinical tests based on the rationales derived from the genetic disease viewpoint.

In a sample of 105 concordant sex MZ and DZ twin pairs, the following characteristics were measured: red cell count, haemoglobin concentration, package cell volume, mean cell volume, mean cell haemoglobin, mean cell haemoglobin concentration, reticulocytes, platelets, white cell count and the six types of leucocytes, lymphocytes, monocytes, band and segmented neutrophils, eosinophils and basophils. The statistical model employed in the univariate twin analysis allows for three sources of variation: genetic (h2), shared environmental (c2) and specific environmental influences (e2). A genetic component was significant for red cell count, haemoglobin and mean cell haemoglobin (0.64, 0.60 and 0.46 respectively), with heritable variation suggested for package cell volume, mean cell volume, mean cell haemoglobin, lymphocytes and monocytes. Shared environmental variation was only present for neutrophils.

Stillbirth rates of MZ and DZ twins in Japan gradually decreased during the period 1960–1967 and in 1974. The stillbirth rates of MZ and DZ twins were 0.270 and 0.224 in 1960, respectively, whereas the corresponding figures in 1974 were 0.135 and 0.099. The stillbirth rate was higher in MZ than DZ twins, in males than females, and in the second- than in the first-born. In both zygosities, the rates were higher in the first birth order than in the second, and then increased with birth order except in the sixth birth or more for MZ twins and for DZ twins born to mothers aged 35–39 years. The shorter the gestational age, the higher the stillbirth rate in both MZ and DZ twins, as expected. Mean gestational age was slightly shorter in MZ than in DZ twins. The decrease of the stillbirth rates can be explained partly by the reduction of twins with higher birth order, where high stillbirth rates of MZ and DZ twins are seen, and the reduction of older mothers.

Provided the assumptions underlying Weinberg's method of differentiation of types of twin pairs are correct, this analysis of the statistics of twin births in Italy in the two years 1949 and 1950 shows that there are variations in the frequency of monovular twin births greater than can be attributed to chance deviations from a constant frequency of monovular twinning. There is a tendency for the frequency to increase with maternal age, and for young mothers, a tendency for it to increase also with parity. In general, the occurrence of monovular twinning is probably more closely related to maternal age than to parity.

The frequency of binovular twinning appears to be independently related to both maternal age and parity. Amongst births of each rank the frequency of twin births increases to a maximum at maternal ages 35-39 years; and, at each age level, the frequency does not change between birth ranks 1 and 2 but subsequently increases fairly continuously. There is a suggestion that there may be a modal birth rank as well as a modal maternal age, and that binovular twinning may be no more closely related to maternal age than to parity.

The birth of twins was believed by the earlier Yoruba communities to be an omen. Drastic measures were adopted in the form of infanticide, or, sometimes, banishment of the twins with their mothers. The ritual killings were gradually replaced by acceptance and reverence of the twins, and thus evolved the kinship cult of twins in which the orisa ibeji, a tutelary deity of twins, became part of the Yoruba pantheon. Twins could be identified in the community by their fixed names of Taiwo and Kehinde. The community prescribes occupations to the mothers, which is learned through consultation with the oracle. The usual forms of occupation, which reflect the nature of the twins, are trading in oil, beans, or clothing, or requesting alms. The orisa ibeji and, by association, the twins were attributed powers of fertility, prosperity, avenger, detector of thieves, and rainmaker. Propitiation and supplication with offerings and sacrifices are an integral part of the cult of twins.

Detailed twin birth rates for the United States are unavailable since 1964. In 1983 the crude twinning rate for women of white race was higher than in 1964, but there had been great changes in maternal age and parity. Indirect standardization for maternal age and birth order provides estimated total twinning rates that can be compared over the entire period. The adjusted rates for whites show a nearly continuous increase except after a 2-year reporting hiatus, 1969-70, when rates dropped back 10%. In blacks the adjusted rate increased between 1966 and 1978, except for the 1968-71 shift. The distributions of rate increases by maternal age and by race argue against effects of medical ovulation stimulants, but a disproportionate increase of triplets argues for such effects. Study is needed of rates specific for maternal age and parity, rather than of total rates.

Self-reported cold data have been analyzed for 95 pairs of identical twins aged 14–64 who took part in a double-blind trial of vitamin C tablets. One member of each twin pair took a tablet containing 1 g vitamin C and the other took a well-matched placebo each day for 100 days. In the total sample there was no effect of vitamin C in preventing colds. However, subdivision of the data showed a significant preventive effect of the placebo in the 51 pairs living together and an equal and opposite preventive effect of the vitamin C in the 44 pairs living apart. The placebo effect in the pairs living together may be attributed to the large proportion who wrongly perceived which treatment they were taking. The reduction of colds in the vitamin C group of the pairs living apart was about 20%. There were significant correlations between cold symptoms reported and the personality trait of neuroticism. No side effects or substantive changes in serum biochemistry could be attributed to the vitamin C dose.

After having examined the literature on the subject, the A. presents the study he has carried on 60 twin-pairs with one or both twins suffering from neurosis or psychosis.

In 50 pairs a psychic suffering of neurotic type was present: out of the 20 MZ pairs, 18 were concordant with a percentage of 90%; out the 30 DZ pairs, 13 were concordant 43%.

Although discriminating the various forms and admitting the interference of environmental factors and other somato-psychic and psychogenetic causes, in 50% of the cases an undoubted psychotic and neurotic heredity was ascertained.

In the four pairs suffering from dysthymic psychosis the 3 MZ were concordant and the DZ discordant.

In the four pairs suffering from schizophrenia the MZ pair was concordant while the 3 DZ pairs were discordant.

In the two pairs of uncertain zygosity the concordance could not be extimated due to the death of the cotwin.

Dysthymia seems to be trasmitted as a dominant character and schizophrenia as a recessive.

Both dystymia and schizophrenia may undergo changes of expressivity with phenotypical characters which can be clinically mistaken as psychoneurotic forms.

Monozygotic twins with typical trisomy 13 are reported. Despite an identical karyotype, the twins were dimorphic for the presence of an omphalocele. Reasons for the rarity of MZ twins with trisomy 13 are presented. It is suggested that the presence of a chromosomal abnormality in MZ twins may predispose to dimorphism.

In his recent book Dr. Roy J. Schepherd states that:

“Further information of genetic effects is likely to be derived from comparisons of identical (monozygotic) and fraternal (dizygotic) twins. Gedda (1961) has already shown that identical twins are more likely to have a similar interest in sports than are fraternal twins. It would be interesting to carry out comparisons of maximum oxygen intake and other objective measurements of endurance fitness on the two classes of twins, but this crucial experiment has yet to be completed”.

We are very glad to be able to announce here that Dr. Schepherd's wish is being fulfilled within the scope of a wider research project undertaken jointly by the Gregor Mendel Institute for Medical Genetics and Twin Research and the Italian Olympic Committee's Institute of Sports Medicine under the auspices of the Italian Sports Medicine Federation.

The studies we have undertaken aim to assess the respective roles of genetic and environmental factors as related to selection and training in sports and physical education.

The twin method affords, through a comparison of MZ and DZ within-pair concordances, an assessment of the degree of genetic conditioning in any individual trait.

It is quite obvious that the possible influence of training on any given trait is inversely proportional to the degree of genetic conditioning of the same trait.

If a given trait, required for a certain type of activity, is completely or almost completely conditioned by the genotype, we should seek those who have inherited it from their parents without wasting time and effort in useless training sessions.

As we can see, the scientific information we are seeking has great practical importance in the selection and training of athletes in every single field of sports and physical education.

A Cox proportional hazard regression analysis was carried out that evaluated age-specific death risk among 21,890 twins born in Sweden during 1886 through 1925 and followed during 1962 through 1980. Cotwin's survival was used as the primary covariable, and auxiliary covariables were smoking, marital status and, among men, police registration for alcohol abuse. In each age, sex and zygosity group, except the oldest DZ males, cotwin's mortality had a significant, independent, positive relationship to the mortality risk of the individual. The auxiliary covariables, except marital status among females, had significant, independent, positive relationships to mortality among the youngest twins of both zygosity groups and in the middle age group of MZ twins. In the oldest age group, the death of MZ cot wins was the only variable significantly related to the individual's mortality. Heritability estimates for the age-specific probability or death risk, developed by different methods for different analysis groups, range between 0.4 and 0.6. They have reasonable internal consistency, are not much affected by the covariates, and are in agreement with other studies that did not control covariates.

A group of 34 twin pairs was studied at four years of age. Characteristics of the group were a homogeneous social background, good parental interrelationship and conscientious care during pregnancy, delivery and the neonatal period. All the children were tested with the Griffiths' Mental Development Scales. The girls generally showed a higher development quotient than the boys. Birth weight seemed to be the most important factor; at 4 years of age, the twins with a birth weight of less than 2500 grams had a significantly lower locomotor quotient. The langage quotient showed a similar trend. This difference was, however, not significant. No significant differences in either locomotor or language development could be observed between MZ and DZ twins.

By cytological diagnosis of chromosomal sex it has been shown, that about 80 per cent of all cases of gonadal dysgenesis are genetically male. In about 8 per cent of male individuals various defects of red-green sensitivity may be expected. Deuteranopia was observed in a hetero-gametic pseudo-female with testicular dysgenesis. Tests for colour vision should be made in all patients with the syndrome of testicular feminization. From such tests a decision may be expected between sex- linked recessive and autosomal dominant transmission with sex limitation.

Fourteen triplet deliveries conducted between 1 January 1981 and 30 June 1986 at the principal teaching hospitals of Northwestern University Medical School are reviewed. Maternal demographic characteristics are listed, as are the obstetric outcomes, including mode of delivery, and the fetal outcome. The recent literature of triplet delivery is reviewed.

The rate of triplet delivery in our study was 0.37 per 1,000 live births. About two-thirds of the pregnancies resulted from the use of fertility-inducing agents. Ultrasonic confirmation was available in all cases. The majority of women were delivered by cesarean section (85%). No consistent pattern of presentation was seen. The mean weight of all 42 infants was 1,779 g (± 594). Unlike-sex triplets accounted for most of the sets (77%). The mean 5-min Apgar score of all infants was 9 and had no association with the order of deliveries. The weight differences by sex regardless of birth order were clinically insignificant. Neonatal mortality was 2.3%

Applying newly devised model, heritability (VA/VP) of plasma uric acid level, corrected for age and sex and standardized, was estimated at 0.8 in families consisting of twin parents, spouses and children. Correlation between spouses due to common genotype (ρ) was approximately 0.1, and variance due to common familial environment (VEC/Vp) was -0.3. Analysis of families of selected twin children and their parents resulted in two estimates of heritability: approximately 0.7 and 0.3, ρ being 0.34 and 0.04, and VEC/Vp being 0.04 and 0.34, respectively. Regression of IQ (y) on corrected and standardized plasma uric acid level (x) in the twin children was y = 5.56x + 123, correlation being 0.334 (p < 0.025). The result indicates a genetic basis of blood uric acid level, which may have resulted from polymorphisms in purine metabolism pathway, end product of which is uric acid in man. The significant correlation between plasma uric acid level and IQ suggests a contribution of partly common gene loci to the two quantitative traits.

A family investigation has been carried out on 301 consanguineous and the same number of nonconsanguineous couples, who married in Florence in the years 1939 through 1958. The sample turned out to be homogeneous as regards age of the couple, year of marriage, period of cohabitation, social level, and methods of survey.

The average rate of consanguinity in Florence in the above years was of 0.458 × 10−3, with a decrease from 0.595 to 0.327 × 10−3 between the first and the second decade.

While the number of pregnancies is not significantly different in the two groups, abortions are more frequent among blood relatives. As a result, the number of stillbirths being not significantly different, the birth rate is higher among the controls. Infant mortality is more than double in blood relatives. As regards morbidity, hereditary defects or anomalies show an average increase of 2.6 times in the offspring of blood relatives: the increase being higher for serious hereditary defects (3.44) than for lighter ones (1.98). The finding of slight delays in mental development was 4.8 times more frequent in the offspring of blood relatives.

By applying Morton-Crow-Muller's formula, it was possible to calculate the A and B values, and to find out, in the observed population, the presence of 2.2-2.4 pathological gene equivalents per gamete as to early mortality (abortions + stillbirths + infant mortality); 1.6-1.7 gene equivalents as to hereditary defects in general; and 0.82-0.85 gene equivalents as to slight delays in mental development.

Old-age twinning rates were evaluated over a period of 250 years (1611-1860), from 80,256 parish records of baptism in a church office in Görlitz, East Germany. Two periods with high and two periods with low twinning rates were observed. Twinning rates were relatively stable in spring and fall, but varied greatly in winter and summer.

This study describes a 5-year survey of activity in a single institution, and the effects of a change of policy for prevention of preterm birth in twin pregnancies.

The results show the advantages and drawbacks from the financial and medical viewpoints.

Dermatoglyphics of 81 females with Turner's syndrome are analysed with regard to the cytogenetic findings and they are compared with the data from normal relatives of both sex. The quantitative traits (total ridge count, a-b ridge count, atd angle) are shifted to an elevation of the means. Centric patterns on the hypothenar area as well as a longitudinal alignment of the main lines and transverse creases are found rather frequently. Previous studies are confirmed.

The theory of r selection, favoring population growth, as opposed to K selection, favoring more efficient utilization of resources, has in recent years been applied by Rushton to contrast human ethnic groups in terms of their r/K reproductive strategies, suggesting the existence of a continuum from r groups, producing many offspring but providing little parental care, to K groups, producing few offspring but providing much parental care. Rushton's theory, which is largely based on ethnic differences in twinning rates, is here critically examined. It is pointed out that twinning rate differences are not necessarily genetic in origin since various environmental factors clearly play a role, and also that twinning, as a mode of reproduction, is not necessarily an r strategy, considering the high prenatal and perinatal selection to which it has been, and still is, associated. Moreover, Rushton misinterprets a number of relevant aspects related to the biology of twinning. The claim that ethnic differences in twinning rates provide evidence for an r/K typology in human populations with respect to reproductive strategies does not appear to be warranted.