Jan A. Böök

Schizophrenia in a North Swedish geographical isolate, 1900–1977. Epidemiology, genetics and biochemistry

Over 200 schizophrenic patients belonging to three major and interrelated pedigree complexes have been investigated over the past 30 years in a North Swedish geographically isolated population, presently numbering about 6,000. An intensive investigation of a number of biochemical correlates and genetic markers in a few selected families belonging to one of the major pedigrees has indicated new strategies for the current research program.

Platelet monoamine oxidase in a pedigree with schizophrenia: an interlaboratory project.

Conflicting reports on the association between platelet MAO activity and schizophrenia prompted a critical review and determinations on identical samples at one laboratory in Sweden and one in the USA. Samples originated from eight schizophrenics and 27 relatives belonging to a large pedigree, thus ensuring biological homogeneity.

GENETICS AND BIOCHEMISTRY OF SCHIZOPHRENIA IN A DEFINED POPULATION

ABSTRACT Over 200 schizophrenic patients belonging to three major and interrelated complexes have been investigated. A major dominant gene is operating in these pedigrees. Hypotheses that schizophrenia might be caused by gene controlled deficiencies in the catecholamine metabolism were tested in a few selected families. Schizophrenia was significantly associated with decreased activities of dopamine-hydroxylase (DBH) in plasma and monoamine oxidase (MAO) in platelets and with the genetic marker Gc 2 (Group specific antigen). There was no significant difference in the catechol-0-methyltransferase (COMT) activity in the red blood cells between schizophrenics and their non-schizophrenic relatives.

Plasma dopamine β-hydroxylase activity in a North Swedish isolate with a high frequency of schizophrenia

Plasma dopamine β‐hydroxylase (DBH) activity was determined in 115 members of a North Swedish geographical isolate with a high frequency of schizophrenia, of which 30 persons had schizophrenia, and was compared with a Middle Swedish population of 185 apparently healthy persons. There was no significant difference between the schizophrenic group and their healthy relatives or between the North and Middle Swedish populations. The number of persons with very low plasma DBH activity in the North Swedish population appeared to be less than those in the control population.

Epidermal ridge configurations in a boy with triploid-diploid mosaicism.

The palm prints of a 2A,XY/3A,XXY patient displayed a scarcity of patterns and a wider than normal atd angle. Both hands had typical four-finger lines. The digits of the right hand had radial loops on II, III and V.

DNA synthesis of human XYY cells. Autoradiography and fluorescence pattern.

The autoradiographic YY labelling pattern of the DNA replication in 47, XYY cells of two patients has been studied. Both Y chromosomes began DNA replication simultaneously but later than the rest of the chromosomes. During later stages the YY labelling pattern in both patients was correlated to the position of the cells in S, as indicated by the cell grain count: in cells with more than approximately 500 grains the synchronous labelling of the Y chromosomes was the rule; whereas during later stages in cells with approximately 100–400 grains, synchronous as well as asynchronous labelling in the same patient was found. In cells with less than about 100 grains, both Y chromosomes usually had completed replication. No obvious difference between the labelling pattern of the two Y chromosomes was found when cells from the 2 patients were compared at the same stage of S. Our results demonstrate the importance of analysing cells of comparable developmental stages of S when comparing DNA labelling patterns of different XYY individuals in search of a possible correlation between labelling pattern and phenotypic expression of the syndrome.

A pedigree with essential myoclonus and genetic spastic oligophrenia

A pedigree with 7 cases affected with essential myoclonus and 3 cases affected with genetic spastic oligophrenia is reported. These two conditions show independent segregation. Essential myoclonus is apparently a very rare syndrome. Where the few earlier and relevant reports are considered, this syndrome is operationally defined and explained as probably caused by a single major gene difference with clinical manifestation in about 60 per cent of heterozygotes. For counseling purposes the genetic risks for children of one affected parent and for siblings of an affected child appear to be about 30 per cent. The data, however, are still scanty and more exact information about this syndrome is needed.

Schizophrenia and suicide in a North Swedish isolate, 1890–1980

The epidemiological and genetic investigation of schizophrenic psychoses over the period 1900–1978 which has been carried out in a specified North Swedish geographical isolate was supplemented with a study of suicides. For the period 1890–1980, a total of 90 suicides have been ascertained. Of these, 54 had at least one schizophrenic relative at a maximum genetic distance of 1/8, while 11 had schizophrenic relatives further removed. It is likely that at least some of these suicides were manifestations of acute and/or undiagnosed psychoses. Thus the previously reported high general morbid risk of schizophrenia in this population (2.7%) would be a rather conservative estimate. On the other hand, the findings would not appreciably change the morbid risk for first‐degree relatives of schizophrenic probands.

Biology of human intelligence.

The article presents a brief review of the genetic aspects of intelligence as measured by IQ tests. The results from family and twin investigations seem to agree in as much as high heritabilities for IQ can be calculated. There are, however, a large number of insecurities and sources of error which invite to criticism. Although, at present, it is justified to assume that genetic factors contribute substantially to variations in IQs, it would be premature to claim that genetic and other causes of variation could be expressed in precise figures. It seems doubtful if this situation could be further improved by continued use of IQs in genetic investigations. It should be more profitable to use other entities, such as well-defined special abilities, which could be designed directly for genetic analyses.

Genetic aspects of schizophrenia

Sufficient evidence supports the conclusion that schizophrenia syndromes are pathogenetically and very likely genetically heterogeneous. The major part of published data on families and twins suggests a significant genetic variation component. The interpretation of the genetic transmission is probably confounded by the heterogeneity of such data.