Fragile X-linked mental retardation of macro-orchidism.

A fragile site near the end of the long arm (q) of the X chromosome appears to be directly related to the gene responsible for the mental retardation found among males and some females who possess this variant X chromosome. Macro-orchidism is present in most males studied. Other mild phenotypic similarities may exist. The expression of the fragile X (fra[X]) chromosome is dependent on the concentration of folic acid and thymidine in the culture medium, which partly explains why fra(X) was not noted earlier and connected promptly with X-linked mental retardation. Whereas prenatal diagnosis is now possible, genetic counseling is complicated by recent reports of "intellectually normal" fra(X) males. Further studies are needed to form solid conclusions about intellectual deficits, learning behavior or personality characteristics of fra(X) persons.

[1]  P. Howard‐Peebles,et al.  X‐linked nonspecific mental retardation:Report of a large kindred , 1976, Clinical genetics.

[2]  H. Lubs.  A marker X chromosome. , 1969, American journal of human genetics.

[3]  J. Bell,et al.  A PEDIGREE OF MENTAL DEFECT SHOWING SEX-LINKAGE , 1943, Journal of neurology and psychiatry.

[4]  G. Turner,et al.  X-linked mental retardation, macro-orchidism, and the Xq27 fragile site. , 1980, The Journal of pediatrics.

[5]  P. Jacobs,et al.  X-linked mental retardation: a study of 7 families. , 1980, American journal of medical genetics.

[6]  J. Fryns,et al.  X-linked recessively inherited non-specific mental retardation. Report of a large family. , 1977, Annales de genetique.

[7]  Howard-Peebles Pn.  Fragile sites in human chromosomes II: demonstration of the fragile site Xq27 in carriers of X-linked mental retardation. , 1980 .

[8]  W. Brown,et al.  FEASIBILITY OF FRAGILE X CHROMOSOME PRENATAL DIAGNOSIS DEMONSTRATED , 1981, The Lancet.

[9]  M. Mikkelsen,et al.  Marker X chromosome induction in fibroblasts by FUdR. , 1981, American journal of medical genetics.

[10]  G. Sutherland.  Fragile sites on human chromosomes: demonstration of their dependence on the type of tissue culture medium. , 1977, Science.

[11]  T. Glover,et al.  FUdR induction of the X chromosome fragile site: evidence for the mechanism of folic acid and thymidine inhibition. , 1981, American journal of human genetics.

[12]  S. Wiener,et al.  Familial X-linked mental retardation with an X chromosome abnormality. , 1977, Journal of medical genetics.

[13]  A. Dekaban.  Persisting clone of cells with an abnormal chromosome in a woman previously irradiated. , 1965, Journal of nuclear medicine : official publication, Society of Nuclear Medicine.

[14]  P. Jacobs,et al.  Marker X syndrome in an oriental family with probable transmission by a normal male. , 1982, American journal of medical genetics.

[15]  P. Jacobs,et al.  More on marker X chromosomes, mental retardation and macro-orchidism. , 1979, The New England journal of medicine.

[16]  G. Turner,et al.  Marker X chromosomes, mental retardation and macro-orchidism. , 1978, The New England journal of medicine.

[17]  J. Gerrard,et al.  Familial sex-linked mental retardation. , 1962, Canadian Medical Association journal.

[18]  P. Chidiac,et al.  FRAGILE X IN A NORMAL MALE: A CAUTIONARY TALE , 1981, The Lancet.

[19]  G. Turner,et al.  X-linked mental retardation associated with macro-orchidism. , 1975, Journal of medical genetics.

[20]  D. Pitt,et al.  TRANSMISSION OF FRAGILE (X) (q27) SITE FROM A MALE , 1981, The Lancet.

[21]  G. Sutherland.  Marker X chromosomes and mental retardation. , 1977, The New England journal of medicine.

[22]  G. Sutherland,et al.  X-linked mental retardation with macro-orchidism and the fragile site at Xq 27 or 28. , 1979, Human genetics.

[23]  Heterozygous expression of X-linked mental retardation and X-chromosome marker fra(X)(q27). , 1981, The New England journal of medicine.

[24]  G. Stoddard,et al.  Familial X‐linked mental retardation with a marker X chromosome and its relationship to macro‐orchidism , 1980, Clinical genetics.

[25]  G. McBride.  Fragile X chromosome related to mental retardation in males. , 1979, JAMA.

[26]  J. Hobbins,et al.  PRENATAL DIAGNOSIS OF FRAGILE X CHROMOSOME , 1982, The Lancet.

[27]  F. Hecht,et al.  Inducing fragile sites to express themselves. , 1980, American Journal of Human Genetics.

[28]  G. Stoddard,et al.  Familial X-linked mental retardation, verbal disability, and marker X chromosomes. , 1979, American journal of human genetics.

[29]  G. Sutherland.  Heritable fragile sites on human chromosomes I. Factors affecting expression in lymphocyte culture. , 1979, American journal of human genetics.