Abstract
The result of a previous study showing an association between mental development and fragile X activity in heterozygous females is given further support by similar investigations of three additional kindreds. The increased frequency of demonstrable fragile X chromosomes in mentally retarded females appears to be due to an increase in the active fragile X while the inactive marker X remains at a similar low frequency in all heterozygotes whether retarded or not. The frequencies of the active fragile X separated the normal and abnormal subjects into two distinct populations. The suggested inverse correlation between the number of lymphocytes with detectable fragile X chromosomes and advancing age can be attributed to ascertainment biases.
Full text
PDF
Images in this article
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Carpenter N. J., Leichtman L. G., Say B. Fragile X-linked mental retardation. A survey of 65 patients with mental retardation of unknown origin. Am J Dis Child. 1982 May;136(5):392–398. [PubMed] [Google Scholar]
- Herbst D. S. Nonspecific X-linked mental retardation I: a review with information from 24 new families. Am J Med Genet. 1980;7(4):443–460. doi: 10.1002/ajmg.1320070406. [DOI] [PubMed] [Google Scholar]
- Howard-Peebles P. N. Fragile sites in human chromosomes II: demonstration of the fragile site Xq27 in carriers of X-linked mental retardation. Am J Med Genet. 1980;7(4):497–501. doi: 10.1002/ajmg.1320070410. [DOI] [PubMed] [Google Scholar]
- Jacobs P. A., Glover T. W., Mayer M., Fox P., Gerrard J. W., Dunn H. G., Herbst D. S. X-linked mental retardation: a study of 7 families. Am J Med Genet. 1980;7(4):471–489. doi: 10.1002/ajmg.1320070408. [DOI] [PubMed] [Google Scholar]
- Sutherland G. R. Fragile sites on human chromosomes: demonstration of their dependence on the type of tissue culture medium. Science. 1977 Jul 15;197(4300):265–266. doi: 10.1126/science.877551. [DOI] [PubMed] [Google Scholar]
- Sutherland G. R. Heritable fragile sites on human chromosomes. III. Detection of fra(X)(q27) in males with X-linked mental retardation and in their female relatives. Hum Genet. 1979;53(1):23–27. doi: 10.1007/BF00289445. [DOI] [PubMed] [Google Scholar]
- Turner G., Brookwell R., Daniel A., Selikowitz M., Zilibowitz M. Heterozygous expression of X-linked mental retardation and X-chromosome marker fra(X)(q27). N Engl J Med. 1980 Sep 18;303(12):662–664. doi: 10.1056/NEJM198009183031202. [DOI] [PubMed] [Google Scholar]
- Turner G., Daniel A., Frost M. X-linked mental retardation, macro-orchidism, and the Xq27 fragile site. J Pediatr. 1980 May;96(5):837–841. doi: 10.1016/s0022-3476(80)80552-x. [DOI] [PubMed] [Google Scholar]
- Uchida I. A., Joyce E. M. Activity of the fragile X in heterozygous carriers. Am J Hum Genet. 1982 Mar;34(2):286–293. [PMC free article] [PubMed] [Google Scholar]