A case of one twin pair concordant or discordant as to a given disease is always very important for Clinical Genetics, especially when it is monozygotic. In Clinical Genetics, isolated pairs occur to the physician, and the diagnosis must therefore be based on intra-pair comparison. The statistical treatment of the case must consider the fact that a concordant monozygotic twin pair represents a statistical universe rather than a statistical unit. This entails taking into account many traits concerning the time of onset, the symptoms, development, result of treatment, etc. Suggestions are made for the statistical treatment of such cases.

The Authors describe the results obtained by their studies concerning the reaction of histocompatibility to homografts, the origin of parvicellular infiltration and regional lymphonodular modifications due to a skin graft.

The acceptance or reject of a homograft in rabbit twins makes it possible to establish the presence of MZ twins. As for the parvicellular infiltration, noticed in the case of kidney homografts, according to the researches of the Authors, who have depressed the graft by means of irradiation, it may be assumed that it is originated either from the graft, or from the host.

The study of regional lymph-nodes in the skin homograft in rabbit shows an evident proliferation of the lymphoreticular tissue starting in the very early days, when the graft is viable; in a subsequent stage corresponding to the graft's elimination there is a clear prevalence of plasmocytary elements in the lymphatic cords.

The homograft in mice of the inbred line C57 BL6 shows the graft's acceptance by tissural reactions equivalent to the ones of the autograft.

The homograft from random mouse on inbred mice shows the absence of a histiocytary lymphonodular reaction of the epithelioid type, which may be observed sometimes in the reaction to the allogenic homograft in the rabbit; it would be then a subsequent reaction not related to histocompatibility phenomena.

The Autor gives a genetic interpretation of homosexuality. A first division may be done between homosexuality cum materia and sine materia. For instance we speak of homosexuality cum materia in the case of such adrenogenital syndromes in which an augmented secretion of androgens may orientate the females towards the male direction, including psychological inversion. As for homosexuality sine materia, the Author reports the twin data by Kallman demonstrating, by means of a new statistical analysis, the presence of hereditary factors. According to the Author such cases could be microforms of inherited endocrine diseases originated by an enzyme affection, or equivalents of inherited psychiatric diseases.

The Authors have investigated the problem of foetal membranes in monozygotic and dizygotic twin pregnancies. The material consisted of anamnestic information derived from the twin case files of Rome's Mendel Institute.

In a sizable number of twin cases (3, 107) it was possible to establish zygosity and the various frequencies of monochorionic or dichorial single or double placenta.

Statistical analysis of this material shows that the frequency of monozygotic twin pregnancies with one placenta and one chorion is 68.35%, while 31.65% have two placentae and two choria. On the other hand, 83.29% of dizygotic twin pregnancies have two placentae and two choria, while 16.71% have one placenta and one chorion.

These figures exceed the material's margin of error, calculated on the basis of an appropriate index. Some case, diagnosed as bichorial with one placenta, are explained as due to two placentae fused into one piece, causing a mistaken diagnosis at birth.

The Authors report on a pair of MZ twins, only one of which affected by the Duchenne-type myopathy. Monozygosity is supported by the success of a reciprocal skin-graft.

Various hypotheses are discussed, including that of a somatic mutation during the first division of the egge producing the twins.

The Authors describe a case of aplasia of the upper limbs in a discordant MZ twin pair. According to the individual and genealogical findings, and especially to the fact that these female MZ twins are discordant, as well as to the caryologic finding, the Authors conclude that the malformation is not genetically induced but possibly originated by blastophthoric factors during the first and second month of fetal life.

The deterioration of mental health of our population is usually interpreted as the result of the increased modern life stress in our atomic age with its implications of the « cold war ». It is not a greater cultural life stress, however, but rather a lower individual resistance to it that accounts for the increased frequency of psychoneuroses in modern society. The term « mental retardation » comprises two categories: one is caused by genetic factors or acquired intra-and extrauterine diseases of infancy and childhood, the second is due to functional mental retardation if the normal individual genetic endowment has not developed to its full capacity and has persisted in a state of immaturity without any interference of a disease. The characteristics of such functional mental retardation (psychic infantilism) and their manifestation in society are outlined in detail. Instincts and emotions insufficiently inhibited by intellect determine the behavior of the functionally mentally retarded. Deficient ethics and responsibility are very often consequences of deficient intellect. Conformism is a subterfuge and evasion from personal responsibility. Exuberant imagination and fantasy of an immature mind, uncontroled by intellect, becoming prevalent in a schizoid personality have eliminated the concept of beauty-and this is the essence of aesthetics-from creative art, music and literature. Mental hygiene is chiefly the job of the family home and the teachers in primary and secondary schools. Education is more than drill and training. Teachers cannot be replaced by machines. Automation technics, recently used even for personality assessment, are out of place in this field.

The reported cases of aseptic gangrene of the skull in a brother and his sister, induce the Authores to reexamine the present theories on the etiopathogenesis of primitive gangrene of the newborn and to put forth the hypothesis of a hereditary etiology. The Authors stress the consanguinity of the parents and interpeter the case as a localised skull aplasia probably inherited with a recessive monomeric hereditary mechanism.

Weights of mineralized dental tissue have been determined in incisors dissected from ten pairs of twins failing to survive beyond 7-8 months' gestation. Logarithms of weights were compared as ratios (lower/upper) with data from foetuses of similar development. Intra-twin differences were thus shown to be significantly less than inter-twin differences when comparing central incisors. Lateral incisors were too variable to allow this demonstration. The linear regression equation combining logarithms of lower and upper central incisor weights was suitable for estimating foetal age to within one week of the recorded age.

The present report is of an infant male twin (Don) who developed a depressive illness with onset at 8½ months of age. At 22 months of age, Don's depressive expression and attitude gave way to an expression of toughness which was rewarded by the mother's increased attention to him when he would show his « though look ». Such a transformation of affect in Don is understood as partly adaptational (object capturing), partly defensive (denial of object loss), and partly characterological (counter-phobic attitudes developed). The twin sister, Donna, toward whom the mother was much closer, was spared such an illness. The presence of depression in Don and the lack of it in Donna is understood on the basis of interrelated experiential and constitutional (genetic and maturational) factors in development.

The study is reported in order to illustrate the use of twins in the exploration of differences, both constitutional and environmental, which surround development in boys and girls, while the parents's stage of development remains constant.

1. We collected 27 pairs of twins (MZ 21, DZ 6) ranging from 41 to 80 years, and 16 pairs of homosexual siblings (SL) ranging from 62 to 90 years, all of whom were Japanese in the western district of Honshū-Island. First, we measured the bodily constitution, certain body parts and certain bones, and investigated their life- histories. Next, we investigated various senescent phenomena. That is: — the approximate number of gray hairs on the head, the appearance and the size of alopecia senilis in the parietal region, the approximate number of wrinkles in the frontal region, the comparative number of sulci cutis on the nape of neck, the back of the right hand, and the anterior chest, the development of senile pigment spots on the face, the back of the right hand, the extensor surface of the right forearm, and the upper half of the back, the appearance of the senile wart, the development of pinguecula, the development of arcus senilis, the development of marginal protuberances on the lumbar vertebral bodies, and the upper end of the tibia, the existence of fabella in the right knee, and the calcification in the wall of the arch of the aorta.

With regard to these items we calculated the middle percentage deviation, the coefficient of correlation, or the rate of concordance, and on the photographs or X-ray photographs the resemblance between both partners was examined.

2. We have concluded that the following items are mainly subject to the control of heredity. That is, the approximate number of gray hairs on the head, the existence, the localization and the shape of alopecia senilis on the parietal region in ♂, the localization and the shape of wrinkles on the frontal region, the localization and the development of senile pigment spots on the face, the development of pinguecula and of arcus senilis of the eye, the development and the shape of marginal protuberances on the lumbar vertebral body, and the development of marginal protuberances on condylus lateralis et medialis of the tibia. On the other hand, the following items were found to be fairly subject to influence of the environmental factors. That is, the appearance of alopecia senilis on the parietal region in ♀, the number of wrinkles on the frontal region, the comparative number of sulci cutis on the nape of neck, the back of the right hand, and the anterior chest, the number of senile pigment spots on the back of the right hand, the extensor surface of the right forearm, and the upper half of the back, the appearance of senile wart on the body, and the calcification in the arch of the aorta.

3. Concerning those senescent phenomena, which are strikingly subject to the control of heredity, a certain degree of difference between both partners of MZ was sometimes recognized. When the differences in the progression of various senescent phenomena between both partners of MZ were observed, it was often recognized that some senescent phenomena make more progress in one partner, while on the other hand the other ones do in another partner.

4. In order to decide certain environmental factors, which have influence upon the difference between both partners of MZ, we referred to the existence of heavy labor for long duration, the number of deliveries, the grade of the sunburn, the habit of alcoholic drinking, smoking, and history of various diseases. However, we could not decide that some of these factors had certain definite relationship with the progression of certain senescent phenomena. However, we might probably presume that the old-styled Japanese hair dressing worn for many years had a certain relationship with the appearance of the baldness in ♀.

A study is described in which the spectral similarities in the voices of monozygotic, dizygotic and non-twin controls is compared. The results are based on a statistical comparison of the differences between pairs of individuals at a number of spectral points. The data are interpreted as showing that monozygotic twins are more similar in the higher but not the lower spectral ranges. It is suggested that the lower frequencies are more sensitive to transitory factors while the higher frequencies are more likely to reflect anatomic similarity.

A sibship is described showing partial aplasias of lower and upper limbs. The concordance of the malformations in the two brothers, the presence in the ascendents of various skeletal and extra-skeletal anomalies, as well as the lack of other causes which could have originated the malformations have made us diagnose the genetic origin of the malformation.

1. A tapeto-retinal degeneration can be observed in association with a disturbance in the metabolism of the lipids.

2. This fact gives a new argument in favor of the hypothesis that the tapeto-retinal degeneration is due to a metabolic alteration and more probably to an enzymatic disturbance in the sensorial epithelium of the retina.

3. The investigations of Hooft et al (1962) demonstrate that it may be an insufficiency of the pyridine nucleotide coenzymes following a primary disturbance in the metabolism of tryptophane.

4. In a case of pigmentary retinopathy, it is now indispensable to do a systematic blood examination both on the morphological and on the biochemical and metabolic point of view.

A family of Iranian-Jewish origin with two hereditary enzymatic defects in the red blood cells, catalase deficiency and glucose-6-phosphate dehydrogenase deficiency, is described. The two enzymatic defects were inherited independently of each other. The findings are compatible with a transmission of the catalase deficiency by an autosomal gene of incomplete dominance, the homozygous state resulting in severe catalase deficiency and the heterozygous state in intermediate catalase deficiency.

The clinical and histologic observations in an 18-year old male with osteopoikilosis are described. Twenty-four of the proband's relatives were roentgenographed; films were taken of their pelves, hips, knees and elbows. The father was found to have osteopoikilosis, but none of the others were affected.

It has been attempted to figure out how osteopoikilosis is transmitted by a study of the family data given in the literature. Though it is realized that these data are biased because of their selective nature, it is suggested that osteopoikilosis is inherited as an autosomal dominant disease.

In an anatomo-pathologic investigation on 21 twins (9 pairs and a set of triplets) who had died within 26 days from birth, the Authors have found a majority of lesions of the respiratory system (in 5 cases hyalin membrane, in 4 bronchpneumonia, in 10 desquamative alveolitis associated with atelectasia, emphysema, congestion, haemorragiae, ouedema and substances ab ingestis). Interval between cotwin death lies between 15-18 hours in 8 pairs, 12 days in one pair, 15-11 hours in the triplet set. The highest frequency of mortality was between the 11th and the 16th day: 55%, which differs from that for single born prematures and immatures. Qualitative and quantitative concordance of lesions was remarkable in seven pairs.

In one pair of twins, who died within 30 hours of each other, only the type of prevailing exsudate differred (leucocytes in one, monocytes in the other), while the degree of the lesions was similar. In another pair of twins, whose death was due to exsudative respiratory lesions, one, dead on the 2nd day, exhibited the symptoms of hyalin membrane syndrome, and the other, dead on the 14th day, the symptoms of bronchpneumonia. The two members of the triplet sets who died first, were affected by an egual degree of desquamative alveolitis, while the third, who died 11 hours later, by a leukocyte bronchial catarrh. With regard to the collected data, the Authors proceed with some considerations.

The authors report a case of regional ileitis (Crohn's disease) with an almost identical course in monozygotic twins. Monozygosity is determined by examination of many physical and serological characters.