[The frequency of X-linked mental retardation]. / Chastota X-stseplennoi umstvennoi otstalosti.

600 mentally retarded children, 339 boys and 261 girls aged 5-9 years were examined. Boys to girls ratio (B:G) was found in the total group to be 1.3. Among 257 children with mental retardation of confirmed genetic origin B:G = 1.4, in 129 children with confirmed exogenous defects B:G = 1.04. The significant prevalence of boys over girls was characteristic of children with monogenic forms. The frequency of X-linked mental retardation in the total group, in all mentally retarded boys and in boys with genetic forms was 12.5 +/- 1.3%, 22.1 +/- 2.2% and 28.5 +/- 2.8%, respectively. The frequency of X-linked mental retardation was higher in boys with genetic forms of imbecility.

[Polymorphism of clinical manifestations and characteristics of imbecility in the Laurence-Moon-Biedl syndrome]. / Polimorfizm klinicheskikh proiavlenii i osobennosti slaboumiia pri sindrome Lorensa-Muna-Barde-Bidlia.

The incidence of all feasible phenotypic variants and clinical forms of the disease observed by neurologists and psychiatrists are calculated using probabilistic approaches. The Laurence-Moon-Barde-Biedl syndrome course and related dementia features were studied in 7 children of 5 families. The patients displayed intellectual degradation with distinct peculiarities in the defect structure.

[Clinical manifestations of oligophrenia with fragile X syndrome in boys in the pre- and post-pubertal age]. / Klinicheskie proiavleniia oligofrenii s lomkoi X khromosomoi u ma'lchikov v do- i postpubertatnom vozraste.

Psychopathological, neurological and somatic manifestations of oligophrenia-with fragile X chromosome were investigated in 13 mentally retarded boys in prepuberty and in 9 such post-puberty++ patients. Age-related features of several psychopathological and somatic signs of the disease were revealed. The authors discuss the possibilities of clinical diagnosis of the disease and stress the importance of its early cytogenetical diagnosis in mentally retarded males.

[Genetic characteristics of recessive sensorineural hearing loss]. / Geneticheskie kharakteristiki retsessivnoi neirosensornoi tugoukhosti.

Genetic characteristics of recessive sensorineural hearing impairment mediated by 5 recessive genes were studied. One of these is responsible for early progressive hearing loss, others causing congenital deafness. The incidence of early progressive recessive hearing loss in a population is 1:20,000, gene frequency being 0.007; the incidence of heterozygotes for this gene is 1.4%. The incidence of each of 4 forms of recessive congenital hearing loss in a population is 1.125:10,000, the frequency of these genes being 0.0106; the incidence of heterozygotes for each of these genes is 2.1%. The total frequency of all recessive genes for sensorineural hearing impairment is 0.0494 and the incidence of heterozygotes for all genes is 9.9%. The frequency of different genotypes for recessive genes specifying sensorineural hearing loss was established, based on the data obtained.

[Incidence of oligophrenia with fragile X chromosome (FraXq27)]. / Rasprostranennost' oligofrenii s lomkoi X-khromosomy (FraXq27).

The study of 50 retarded males imbezilitat and idiots, and 100 males with oligophrenia-debilitat in 16-18 years. Severe macroorchism (1.8-4.5 times more, then anthropometric norma for this years) was found at 5 males in first group (10%), and in 8 males in second group (8%). The karyotype was study in 4 males with macroorchism. In 9-15% cells FraX (q27) was found. These data were extrapolated to 600 retarded children preschool and school age. The frequency of oligophrenia with FraX (q27) among all retarded males-8.5 +/- 1.5; retarded heterozygous females among all retarded girls-5.0 +/- 1.3; incidence of oligophrenia with FraX (q27) among all males in population-1:1000; all heterozigous for this gene among all females in population-7:750; retarded heterozygous females in all girls-1:2250 were established.

[Families with recurrent cases of Waardenburg-Klein syndrome]. / Sem'i s povtornymi sluchaiami sindroma Vardenburga-Kleina.

Deaf children with the type I Waardenburg--Klein syndrome were studied. Secondary cases were found in 14 unrelated and 1 incest families. In 10 families probands and all their affected relatives had the type I Waardenburg--Klein syndrome. In 4 families patients were discovered with both type I and type II syndromes. In an incest family the proband seemed to have the type III, while his mother and father (sibs) had type II and their grandmother the type I syndrome. These results contradict the hypothesis claiming the origin of different types of Waardenburg--Klein syndrome to be due to the action of different genes. It is proposed that types I and II, or all types of the syndrome are caused by a single dominant gene. Potential mechanisms for clinical polymorphism of Waardenburg--Klein syndrome are related to incomplete penetrance and varying expression of this gene.

[Heterochromatic regions of human chromosomes 1, 9, 16 and Y and the phenotype]. / Geterokhromaticheskie raiony khromosom 1, 9, 16 i Y u cheloveka i fenotip.

The relationship between variability of the heterochromatic regions of chromosomes 1, 9, 16, Y and the anthropometric characteristics (the height, the biacromial diameter and weight) was studied in two groups of children; 70 children had embryopathies of unknown etiology and 40 children had the Down syndrome. The positive statistically significant correlation of the C-segments lengths of chromosomes 1, 9, 16, their sum included, and above characteristics was found. The correlation coefficients of Y-chromosome were non-significant. The problems of functional role of the structural heterochromatin and its influence on viability and physical development of the organism are discussed.

[Polymorphism of the heterochromatic regions of chromosomes 1, 9, 16 and Y and mental retardation]. / Polimorfizm geterokhromaticheskikh raionov khromosom 1, 9, 16 i Y i umstvennaia otsatlost'.

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. The chromosome sets of all 150 children were normal. The comparative analysis of chromosome polymorphism of C-segments did not reveal any difference between the controls and the children with a slight degree of mental defect. The children with profound mental defect had reduced lengths and variability of C-segments on the chromosomes studied. The problem of relationship between the criteria of patients selection and the results of the study are discussed. The expedience of further investigation of HR polymorphism in patogenetically homogenous groups of children with mental defect is emphasized.

[Malignant forms of phenylketonuria]. / Zlokachestvennye formy fenilketonurii.

Forty-eight patients with pernicious phenylketonuria (PKU) were examined. It was revealed that the prognostically unfavourable symptoms in relation to the malignant course of the disease included early development of epileptic attacks and neurological disturbances, the small cranial size and early extensive eczematous lesions of the skin. It was established that children with pernicious PKU more often displayed high levels (over 30 mg/100 ml) of phenylalanine and low levels (under 1 mg/100 ml) of tyrosine in the blood as compared with other patients. The results of the study of families with two or more children with PKU suggest that the malignant course of the disease may be observed not only in primary genetic defect of the cofactor and the enzymes reducing it but also in the primary genetic defect of phenylalanine hydroxylase itself. The familial criteria of differentiating between various genetic forms of pernicious PKU are presented and the methods of its treatment are substantiated pathogenetically.

[Heterochromatic regions of chromosomes 1, 9, 16 and Y in children with signs of embryonic development disorder]. / Geterokhromaticheskie raiony khromosom 1, 9, 16 i Y u detei s priznakami narusheniia émbrional'nogo razvitiia.

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.

[Genetic study of sensorineural hearing loss]. / Geneticheskoe izuchenie neirosensornoi tugoukhosti.

Genealogical and genetico-statistical analysis of 639 Moscow families with 696 children suffering from sensorineural deafness was carried out. The patients examined constituted 40% of all the registered cases of hearing loss in children under 16. The study showed that monosymptomatic sensorineural deafness in children was more often of a genetic (62,2%), than of an exogenous (37,8%) origin. 54,2% of children with the disease were born from normal parents and 50,9% of all sporadic cases of sensorineural deafness were caused by genetic factors. In 80,8% of cases, inherited sensorineural hearing loss was transmitted, as an autosomal recessive trait, in 18% - as an autosomal dominant trait and in 1,2% - as a recessive X-linked character. The incidence of recessive sensorineural deafness in children of moscow is 1: 2000, that of dominant hearing loss being 1: 10 000. The total frequency of recessive genes is 0,022; the total frequency of heterozygotes of recessive genes is 0,043.

[Autosomal anomalies in a specially selected group of children with mental retardation without signs of Down's syndrome]. / Anomalii autsom v spetsial'no otobrannoi gruppe detei s oligofreniei bez vneshnikh priznakov bolezni Dauna.

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%). In 21 children (22.0%) there were true autosomal aberrations 1/4 of which were tri- and monosomies, mainly in the form of mosaicism, and 3/4 were non-balanced structural reconstructions of the autosomes. In about 1/3 of the cases the structural anomalies were inherited by the children from their phenotypically healthy parents who had balanced translocations or inversions. In 15 children (15.6%) chromosomal variations were discovered. No differences between the clinical manifestations of the mental retardation in children with true autosomal aberrations and chromosomal variations were noted.