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Query: UMLS:C0025362 (mental retardation)
 15,878 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Chromosome abnormalities with recognizable clinical manifestations including mental retardation, primary infertility or primary amenorrhea of unknown etiology, abnormal sex differentiation and abnormal sex development were surveyed in the general population of Sichuan. The results showed that the prevalence of chromosome diseases in Sichuan was 31.5 per 100,000 of the general population with almost equal frequencies for autosomal chromosome and sex chromosome diseases. The most frequent autosomal chromosome disease was Down syndrome. The prevalence was 14.2 per 100,000 for the total population, and there should therefore be 154,000 cases of Down syndrome in the whole of China with its population of 1,100 million people. The most frequent sex chromosome diseases were Turner syndrome and Klinefelter syndrome. The prevalences were 14.3 and 14.1 per 100,000 for females and males, respectively. The majority of autosomal chromosome diseases clustered in the younger age groups, while the highest detection rate of sex chromosome diseases was found in the age group of 25-35, and thereafter it decreased with age. The age distribution of the cases indicates that both autosomal and sex chromosome diseases reduce the lifespan of patients.
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PMID:The prevalence of chromosome diseases in the general population of Sichuan, China. 201 98

Between 1974 and 1987, 232 translocation carriers have been detected in our Center; they belong to 144 different families. Indications for chromosome analysis were the following: familial studies in relation with a patient suggesting a chromosome anomaly (25.4%); mental retardation with or without malformations (24.6%); 2 or more spontaneous abortions (17.2%); infertility problems, mainly male (16.4%); genetic counseling for a non-chromosomal disease (9.5%); prenatal diagnosis in risk pregnancies (6.9%). The chromosome anomalies detected were the following; balanced Robertsonian fusions (114 cases = 49.1%); balanced translocations (74 cases = 31.9%); unbalanced translocations, Robertsonian fusions included (44 cases = 19%). Two groups may be distinguished: the first one confirms data already known, such as high frequency of balanced translocations in couples with multiple abortions, or in infertile males. The second group on the contrary shows more unusual observations: 4 cases of standard trisomy 21 born to young parents carriers of a balanced translocation not involving chromosome 21; 5 cases of trisomy 13 with 46 chromosomes and a Robertsonian fusion, born to parents carriers of a t(13q; Dq) (twice the mother and thrice the father); 14 cases of apparently balanced translocations, however with an abnormal phenotype; and finally 22 cases of balanced translocations incidentally detected during the course of investigations in patients with a genetic problem generally not associated with a chromosome defect.
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PMID:[Chromosome translocations: study of 232 cases originating from 144 families]. 296 87

This article reviews the effects of alcohol on male and female gonads and hormonal levels; it further discusses the use of ethanol during pregnancy and its teratogenic effect on the fetus. Impotence is a common result of acute alcoholism, and testicular atrophy, infertility, and decreased libido are associated with alcoholism 70-80% of the time. In addition, alcohol consumption produces significant spermatozoal morphological changes involving breakage of the sperm head, distention of the midsection, and curling of its tail. Seminiferous tubules are filled mostly with spermatids that undergo degeneration and result in aspermia. Acute ethanol intoxication is accompanied by decreased plasma testosterone levels and a surge of luteinizing hormone. Ethanol appears to have a dual effect: locally on the gonads and centrally on the hypothalamus-pituitary axis, causing an adverse effect on spermatogenesis. Less is known about the effects of alcohol on the female reproductive function; however, inhibition of ovulation and a significant reduction of plasma estradiol and progesterone levels has been noted in rats following ethanol administration. Alcohol consumption during pregnancy is the most frequent known teratogenic cause of mental retardation. Infants most severely affected by maternal alcohol abuse during gestation possess a number of dysmorphic anomalies termed fetal alcohol syndrome. The abnormalities most typically associated with alcohol teratogenicity can be grouped into 4 categories: growth deficiencies, central nervous system dysfunctions, craniofacial abnormalities, and other major and minor malformations. The effects of maternal alcohol consumption on the fetus are independent of maternal nutritional status and smoking history. Alcohol abuse during pregnancy occurs in 2-13% of US women, and these women have a 50-70% chance of delivering an infant with a serious abnormality.
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PMID:Alcohol and reproductive function: a review. 354 7

In this report the Leuven experience (1970-1984) on reciprocal translocations is summarized. A total of 153 unrelated index patients, carriers of different types of reciprocal translocations, and their families were investigated. Familial reciprocal, apparently balanced translocations were found in 75 unrelated families bringing the total numbers of translocation carrier parents and their offspring to 132 and 445, respectively. In 61.5% of the patients the reciprocal translocation was detected after the birth of a malformed child with unbalanced karyotype or through investigation because of recurrent spontaneous abortions, stillbirths, or infertility. In 41 patients (28 familial and 13 de novo), however, the reciprocal balanced translocation was found to be associated with mental retardation and/or congenital malformations (MR/CM) which is significantly higher than expected. This excess of MR/CM in de novo and familial balanced translocation carriers is illustrated and discussed.
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PMID:Excess of mental retardation and/or congenital malformation in reciprocal translocations in man. 394 58

Trisomy 8, in mosaic or non-mosaic form is an extremely rare chromosomal condition in man. Liveborn subjects usually present with mental retardation, bone and joint anomalies and a variety of other physical anomalies. The mental retardation associated with the condition is, however, usually moderate compared to that found in other viable human autosomal trisomic conditions. The present report describes a trisomy 8 mosaic male subject with normal IQ and near-normal phenotype, ascertained through infertility. Chromosome studies on peripheral blood lymphocytes reveal a pure trisomy 8 constitution; cultured skin fibroblasts show 46,XY/47,XY+8 mosaicism. At meiosis, the extra No. 8 chromosome is missing from the germ line. The testicular histology indicates a germ cell maturation arrest in many spermatocytes and the patient is severely oligospermic. Biochemical studies to assay levels of glutathione reductase, a red cell enzyme, the gene for which resides in chromosome 8, show increased levels in the trisomy 8 patient compared with controls.
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PMID:Trisomy 8. Report of a mosaic human male with near-normal phenotype and normal IQ, ascertained through infertility. 745 Jul 54

We present a large review of 446 cases of paracentric inversions (PAI), including 120 new cases, to assess their incidence, distribution, inheritance, modes of ascertainment, interchromosomal effects, viable recombinant offspring, and clinical relevance. All 23 autosomes and sex chromosomes had inversions. However, none were identified in chromosome arms 18p, 19q, 20q, and Yp. PAI were most commonly reported in chromosomes 1, 3, 5, 6, 7, 11, and 14 and less frequently in chromosomes 4, 16, 17, 18, 19, 20, 21, 22, and Y. Inversions were most common in chromosome arms 6p, 7q, 11q, and 14q and observed least in chromosome arms 2p, 2q, 3q, 4q, and 6q. Frequently encountered breakpoints included 3(p13p25), 6(p12p23), 6(p12p25), 7(q11q22), and 11(q21q23). Ascertainment was primarily incidental (54.5%), mental retardation and/or congenital anomalies (22.2%), spontaneous abortions (11.4%), associations with syndromes (3.0%), and infertility (2.0%) accounted for the remainder. Ascertainment was neither related to the length of the inverted segment nor to specific inversions except for PAI of Xq which often presented with manifestations of Ullrich-Turner syndrome. Sixty-six percent of PAI were inherited while 8.5% were de novo. Recombination was observed in 17 cases, 15 of which resulted in a monocentric chromosomal deletion or duplication. No common factors were identified that suggested a tendency towards recombination. The incidence of viable recombinants was estimated to be 3.8%. This review documents that PAI are perhaps more commonly identified than suggested in previous reviews. Despite the possible bias of ascertainment in some cases, there may be associated risks with PAI that require further examination. Our data suggest that PAI carriers do not appear to be free of risks of abnormalities or abnormal progeny and caution is recommended when counseling.
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PMID:Paracentric inversions in humans: a review of 446 paracentric inversions with presentation of 120 new cases. 905 65

X-linked recessive ichthyosis (XLI) is caused by a deletion, or mutation, of the steroid sulphatase gene on the distal short arm of the X chromosome (Xp22.3). This region of the X chromosome is particularly susceptible to deletions. Such deletions can occasionally extend to involve neighbouring genes, causing a contiguous gene defect. Therefore, XLI may be associated with Kallmann's syndrome (KS), mental retardation, X-linked recessive chondrodysplasia punctata and short stature. We have reviewed 33 patients with XLI. Nine showed evidence of contiguous gene defects. A further four had neurological deficit sustained at the time of birth. This study highlights the importance of screening patients with X-linked recessive ichthyosis for neighbouring genetic disorders and, in particular, the early identification of KS, as delay in diagnosis may lead to infertility and osteoporosis. Parents should be warned about possible obstetric complications due to prolonged labour in future pregnancies.
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PMID:A clinical and genetic study of X-linked recessive ichthyosis and contiguous gene defects. 799 91

A disaster has been defined as a disruption of human ecology that exceeds the capacity of the community to function normally. Little is known about the adverse effects of natural disasters on reproductive outcomes. Important lessons can be derived from several disasters caused by human factors, such as the Minamata Bay disaster. Adverse reproductive outcomes include infertility, early pregnancy loss, stillbirths, congenital malformations, and serious developmental disabilities such as cerebral palsy and mental retardation. Recent disasters like the Chernobyl and Bhopal explosions have provided important lessons on the need for accurate and sound information about the risk of prenatal exposures for adverse reproductive outcomes. To study questions of adverse reproductive outcomes and disasters requires a well-planned approach. It should include early development of surveillance for adverse reproductive outcomes, analytic studies on the risk of disasters from direct and indirect effects, sensitive methods to measure early pregnancy loss, and long-term follow-up programs to assess outcomes such as developmental disabilities.
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PMID:The epidemiology of disasters and adverse reproductive outcomes: lessons learned. 824 83

The reproductive effects of metabolic disorders in women can be divided into four categories. The first of these is infertility. Galactosemia with its complication of ovarian failure is the disorder in this category. This complication may be prenatal in origin but whether this is so and its cause are unknown. The second category includes pregnancy effects of maternal metabolic disorders. The urea cycle disorder ornithine transcarbamylase (OTC) deficiency, maternal maple syrup urine disease and maternal homocystinuria are in this category. In the first two disorders, postpartum life-threatening illness due to metabolic crisis has occurred. Maternal homocystinuria is associated with a high risk for postpartum thromboembolic complications. The third category is the pregnancy effect of a fetal metabolic disorder. Pregnancies in which the fetus had long-chain hydroxyacyl-CoA dehydrogenase deficiency (LCHADD) have been complicated by the life-threatening (HELLP) syndrome during the third trimester. Rapid recovery of the mothers followed delivery, on occasion by emergency cesarean section. The fourth category is the fetal effects (teratogenicity) from a maternal metabolic disorder. The best-known example of this is maternal phenylketonuria (PKU), which produces microcephaly, mental retardation, congenital heart disease and intrauterine growth retardation. Treatment with a low phenylalanine diet begun before conception or no later than the earliest weeks of the first trimester markedly reduces the risk to the fetus and can result in normal offspring. Other examples of teratogenicity may include maternal homocystinuria and maternal hypothyroidism.
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PMID:Reproductive effects of maternal metabolic disorders: implications for pediatrics and obstetrics. 882 3

The prevalence of sex chromosomal anomalies (SCA) is higher after treatment with intracytoplasmic sperm injection (ICSI) than in naturally conceived pregnancies. This finding is not only important in the debate about the genetic safety of ICSI, it also has repercussions on the design of appropriate strategies for prenatal and preimplantation diagnosis in ICSI pregnancies. We discuss here in detail the developmental prognosis of individuals carrying a sex chromosomal anomaly. Major malformations do occur in Turner syndrome, but not so in Klinefelter, the triple X and the XYY syndromes. Infertility represents an almost obligate finding in Klinefelter syndrome, but the latest developments in microassisted reproduction may help to overcome this problem. Importantly, mental retardation does not occur more often in individuals with an SCA than in normal controls. Academic achievement, however, may be somewhat reduced compared with peers. Overall, for most children carrying a sex chromosomal anomaly, a major congenital handicap is not to be expected, and the long-term developmental prognosis is fairly good. Therefore, if an SCA is diagnosed prenatally in an ICSI pregnancy, an unbiased and detailed discussion of the developmental perspectives is warranted. The option of continuing such a pregnancy should be given due consideration.
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PMID:Sex chromosomal anomalies in pregnancies conceived through intracytoplasmic sperm injection: a case for genetic counselling. 922 88


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