ISSN:0148-7299    

DOI:10.1002/ajmg.1320070402

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

ISSN:0148-7299    

DOI:10.1002/ajmg.1320070403

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractWith the exception of macro‐orchidism, three families with X‐linked mental retardation showed diagnostic concordance of clinical features among the affected males. Since macro‐orchidism was a variable feature among the otherwise identically affected males in one family, we question the existence of a separate entity of X‐linked mental retardation characterized only by testicular enlargement. The X chromosome marker of Lubs was expressed, under the culture conditions of Sutherland, in lymphocytes of the affected males of two families, one with and the other without megalotestes. Two affected members of the third family, with megalotestes, did not show the marker. Telomeric structural changes similar to the mar(X) (qter) formation were found on certain autosomes, notably, chromosome 6 in some of the affected males, potential and obligate carrier females, and in both related and unrelated normal males. These autosomal markers appear to represent a nonspecific response to either in vivo or in vitro folate deficiency. Caution against premature introduction of this test for prenatal diagnosis, in the face of current ignorance regarding diagnostic specificity, i

ISSN:0148-7299    

DOI:10.1002/ajmg.1320070404

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractThe family of 2 men with X‐linked mental retardation was investigated for the presence of the marker‐X chromosome and macro‐orchidism. Lymphocyte cultures were set up in media F‐10 and 199. Chromosomes were G‐band‐stained and slides coded for blind analysis. Marker‐X chromosomes and autosomal gaps were seen only in cultures prepared with medium 199. Autosomal gaps were seen in all family members and controls. The marker‐X chromosome was present in affected male (3% and 15.5%) and female family members (0.5%–6.5%) but not in controls or a normal male family member. Bilateral macro‐orchidism was present in 1 affected male and unilateral macro‐orchidism in the other. Both had normal penile measurements. The replication pattern of the marker‐X chromosome was studied in 1 woman by BrdU labelling. BrdU decreases the frequency of marker‐X expression. As the marker‐X chromosome was the late‐replicating X in 9/20 cells, it appears that there is no preferential inactivation

ISSN:0148-7299    

DOI:10.1002/ajmg.1320070405

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractClinical manifestations and other aspects of nonspecific X‐linked mental retardation are reviewed using data from the literature and information on affected males in 24 new families ascertained in British Columbia. A great degree of variability was apparent in the mental abilities of affected males. Speech defects, other CNS disorders and minor physical changes such as “big” ears or a highly arched palate were not present in many cases. Evidence for the existence of a clinical entity of mental retardation associated with the fragile site at Xq27 or 28 and macro‐orchidism is discussed. Genetic phenomena of reduced penetrance in males and of partial expression in females with respect to X‐linked recessive genes are examined. Consideration is given to the question of whether this type of mental retardation is due to X‐linked recessive or autosomal dominant sex‐limited genes. Most ascertained cases of X‐linked mental retardation are from families of northern European extraction. Recommendations are made regarding the diagnosis and counseling of X‐linked mental

ISSN:0148-7299    

DOI:10.1002/ajmg.1320070406

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractData on nonspecific mental retardation in two or more sibs ascertained from the British Columbia Health Surveillance Registry are utilized to calculate the frequency of X‐linked mental retardation in the population of British Columbia (B.C.). In the 1950–1969 birth cohort there are 107 sibships with only males affected and 35 sibships with only females affected giving an excess of 72 male‐affected sibships. Family histories of the sibships with two or more mentally retarded males provide evidence that the mothers of the excess of male‐affected sibships are carriers of X‐linked mental retardation. Thus, a frequency of 1.83 per 1,000 males for X‐linked mental retardation and a carrier frequency of 2.44 per 1,000 females are calculated. This frequency can account for all of the excess of males in the population who are affected with nonspecific mental retardation. We estimate that seven to 19 X‐linked genes exist to cause nonspecific mental retardation, and that the frequency of the marker‐X chromosome, associated with X‐linked mental retardation in some families, may be 0.92 per

ISSN:0148-7299    

DOI:10.1002/ajmg.1320070407

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractSeven families with X‐linked mental retardation (MR) have been studied clinically and cytogenetically. All affected males in six of the families were found to have a fragile site on Xq in a number of their peripheral lymphocytes. The fragile site was not seen in any of the affected males in the seventh family. The affected males in the six families with the fragile X had a syndrome characterized by a variable degree of MR, macro‐orchidism, a characteristic repetitive, jocular speech, normal body proportions, and large jaws and ears.The fragile X chromosome could only be detected in a proportion of female carriers and its frequency in females was found to be correlated with their mental status and to be inversely correlated with their

ISSN:0148-7299    

DOI:10.1002/ajmg.1320070408

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractNine men with X‐linked mental retardation (MR) belonging to the family originally described by Renpenning and his colleagues have been reexamined and restudied. None of these men have the fragile X chromosome, and none have macro‐orchidism; their testes range in size from small to average. All but one are severely retarded; one has an IQ of 70, the mean IQ of the remainder is 30 with a range of 18 to 45. They are short in stature, have small or normal‐size ears and lower jaws, and a moderate degree of microcephaly, the mean skull circumference being just below two standard deviations from the n

ISSN:0148-7299    

DOI:10.1002/ajmg.1320070409

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractDemonstrating the Xq27 fragile site in men with X‐linked mental retardation and in obligate carriers is a continuing problem. I report two additional families with this disorder (Families F and G) and present cytogenetic data on females from four families (D–G). These data and those previously published suggest that there are two types of families in regard to fragile Xq expression in carrier females. One type shows no apparent phenotypic effect in the female and the demonstration of the fragile Xq becomes more difficult with increasing age, whereas the second type is associated with some phenotypic effect (ie, reduction in mental ability), and the fragile Xq can be demonstrated regardless of

ISSN:0148-7299    

DOI:10.1002/ajmg.1320070410

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

ISSN:0148-7299    

DOI:10.1002/ajmg.1320070411

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY