[The C heterochromatin of chromosomes 1, 9, 16 and Y in patients with Noonan's syndrome].

A significant reduction in the total amount of C heterochromatin of chromosomes 1, 9, 16, and Y was detected in six patients with Noonan's syndrome. The results obtained do not contradict the results of our previous investigations of the correlation between a small amount of C heterochromatin and growth retardation. The clinical resemblance of Noonan's and Turner's syndromes with respect to the functional role of facultative and constitutive heterochromatin in early embryogenesis is discussed.

[Nondisjunction of the chromosomes in man. Hypotheses and facts].

The data on nondisjunction of chromosomes in man, and particularly on chromosome 21 in Down syndrome, are presented in this review. New experimental data obtained by the differential staining technique are considered. These data enable us to revise a number of hypotheses on the causes and mechanisms of chromosome nondisjunction.

[Analysis of the inheritance of heterochromatic regions in human chromosomes 1, 9, 16 and Y].

The inheritance of heterochromatic regions of chromosomes 1, 9, 16 and Y was studied in twelve families by means of measuring their C-segments. Maternal and paternal origin of chromosomes 1, 9 and 16 in the child was determined by two methods. The advantages and disadvantages of these methods and possibilities of their application are under discussion.

[Heterochromatic regions and chromosome 21 nondisjunction in man. II. A comparative analysis of the polymorphism of the C bands of chromosomes 1, 9 and 16 in the fathers and mothers of Down's disease children].

To test a hypothesis on potential role of large heterochromatic regions in chromosome non-disjunction, a comparative analysis of C segment lengths of chromosomes 1, 9, and 16 in fathers and mothers of children with Down's syndrome was carried out. No difference was found between the two groups. The non-disjunction in mothers is known to occur 4 times as frequently as in fathers.

[Heterochromatic regions and the nondisjunction of human chromosome 21. I. Polymorphism of the C-bands of chromosomes 1, 9 and 16 in children with Down's syndrome].

To test a hypothesis on potential role of large heterochromatic regions in chromosome nondisjunction polymorphism of C segments of chromosomes 1, 9, and 16 in 70 children with Down's syndrome were examined. The C segment lengths of the above chromosomes were shown not to deviate from the normal. To solve the problem, it seems unreasonable to examine children with Down's syndrome.

[Quantitative assessment of the size of Ag-stained nucleolus-organizing regions in human chromosomes].

The squares of Ag-stained nucleolar organizing regions of metaphase chromosomes have been estimated by scanning their negative images on the film and computer data processing. The intercellular variation of the sum of squares of nucleolar organizing regiones of five individuals was studied. The coefficient of variation for these individuals varied from 11.

[Polymorphism of the heterochromatic regions of chromosomes 1, 9, 16 and Y and mental retardation].

Polymorphism of the heterochromatic regions (HR) on chromosomes 1, 9, 16 and in three groups of boys at the age of 3 to 14 years was studied. Two groups of boys with olygophrenia of unknown etiology differed by the extent of mental defect, the latter being debility in 50 children, while other 50 children had the profound mental defect. The control group consisted of 50 healthy children.

Relationship of the variability of the heterochromatic regions of chromosomes 1, 9, 16, and Y to some anthropometric characteristics in children with embryopathies of unknown etiology and in children with Down syndrome.

The relationship between variability of the heterochromatic regions of chromosomes 1, 9, 16, and Y, and anthropometric characteristics (length and mass of body, shoulder diameter) in 70 children with embryopathies of unknown etiology and in 40 children with Down syndrome was studied. The positive statistically significant correlations of the C segment lengths of chromosomes 1, 9, 16, their sum included, and the above characteristics were found. The correlation coefficients of Y chromosome were not significant.

Heterochromatic regions on chromosomes 1, 9, 16, and Y in children with some disturbances occurring during embryo development.

Some reduction of C-segment lengths and their variability on chromosomes 1, 9, 16, and Y was exhibited by children who had had some disturbances at early stages of morphogenesis. The data obtained might suggest a certain activity of the heterochromatic regions during embryo development. Based on this data one may also suppose that reduction of the amount of heterochromatin might affect the normal morphogenetic processes.

[Heterochromatic regions of chromosomes 1, 9, 16 and Y in children with signs of embryonic development disorder].

Some reduction of the length of C segments and their variability in chromosomes 1, 9, 16 and Y was exhibited by children having disturbances at an early stage of embryogenesis. The data obtained might suggest a certain activity of the heterochromatic regions during the embryo development. Based on these data, one may also suppose that reduction of the heterochromatin amount may affect the normal morphogenetic processes.

[Autosomal anomalies in a specially selected group of children with mental retardation without signs of Down's syndrome].

Pathogenetic examinations of 96 mentally retarded children with multiple somatic anomalies and developmental defects (but without Down's disease) were carried out. Changes of the caryotype were discovered in 36 children (37.5%).

[Variability of the heterochromatic regions of human chromosomes 1, 9, 16, and Y].

The variability of heterochromatic regions on chromosomes 1, 9, 16 and Y has been studied in a group of unrelated subjects (50 boys and 50 girls) using quantitative methods. Analysis of intercellular (with one subject) variability of chromosome C-segments lengths has shown that their absolute lengths vary considerably with the cell sample examined, while the relative lengths (a part of the total length of C-segment of the chromosomes being studied) are more stable. The relative lengths may be helpful in individual characteristics, reproducible in repeated analysis, which may be used in zygosity testing in twins, family analysis, etc.

The quantitative analysis of polymorphism on human chromosomes 1,9,16, and Y. IV. Heterogeneity of a normal population.

The generalized characteristic of the C-segment lengths on chromosomes 1, 9, 16, and Y is suggested for a study of population heterogeneity. For this purpose, the concept of the distance D is introduced, taking into account the individual C-segment lengths, the mean lengths and standard deviations of C-segment lengths in a group of subjects, as well as the coefficients of correlation of the C-segment lengths on the said chromosomes. It is demonstrated that distance D may be employed to study the relevance of the given subject to the group studied, the relation to the mean characteristics within the group, and selection of subjects' pairs with almost identical C-segment lengths on respective chromosomes.

The quantitative analysis of polymorphism on human chromosomes 1, 9, 16, and Y. I. Description of individual karyotypes.

This study was made to establish a stable quantitative characteristic of C segments on chromosomes 1, 9, 16, and Y in an individual karyotype that was reproducible in successive experiments. The C segment of these chromosomes were measured in successive cultures of cells from three males and the C segments of chromosomes 1, 9, and 16 in cells from three pairs of female monozygotic twins were measured. The results show that the absolute lengths of C segments tend to vary considerably with the cell samples analyzed, while the relative length, i.

The quantitative analysis of polymorphism on human chromosomes 1, 9, 16, and Y. III. Study of relationships of C segments' lengths in individual karyotypes.

The correlation relationship of the lengths of C segments on chromosomes 1, 9, 16, and Y was studied in a group of normal boys and girls (50 boys and 50 girls). No correlation was found between the C segment lengths, either on homologs or on chromosomes of various pairs. This confirms the idea of random combinations of the said chromosomes with C segments of different lengths in an individual karyotype.

The quantitative analysis of polymorphism on human chromosomes 1, 9, 16, and Y. II. Comparison of the C segments in male and female individuals (group characteristics).

Comparative analysis of the polymorphism of C segments on chromosomes 1, 9, 16, and Y was conducted in 50 normal boys and 50 normal girls. Quantitative methods revealed that the mean lengths of C segments, their variability, and their distribution on the chromosomes mentioned are quite identical in the two groups. Methodological problems related to the study of chromosome polymorphism are discussed.