Cytogenetically negative, linkage positive "fragile X" syndrome. |
| |
| Authors: | S Sklower Brooks I Cohen C Ferrando E C Jenkins W T Brown C Dobkin |
| |
| Institution: | Department of Human Genetics, New York State Office of Mental Retardation and Developmental Disability, Staten Island 10314. |
| |
| Abstract: | We investigated the family of a 3-year-old boy with manifestations of the Martin-Bell syndrome (MBS). His 17-year-old cousin had classic manifestations of MBS and was fragile X fra(X)] positive. The 3-year-old boy was fra(X) negative. Linkage analysis with probes flanking the fra(X) region indicated that these cousins had the same X chromosome inherited from a normal grandfather. The DNA and cytogenetic analyses suggest that limitations in the ability to detect the fra(X) mutation cytogenetically may be responsible for fra(X)-negative MBS; or, alternatively, that a crossover occurred between a locus determining the MBS phenotype and one determining fra(X) expression. |
| |
| Keywords: | |
|
|
