CHROMOSOME INSTABILITY IN THE SYNDROME OF TRIPHALANGY OF THUMBS, ONYCHODYSTROPHY, DEAFNESS, SEIZURES AND MENTAL RETARDATION

Abstract

Triphalangy of thumbs associated with onychodstrophy, deafness, seizures and mental retardation is a rare autosomal recessive disease. We have observed high frequency of chromosomal breaks in lymphocyte cultures from two affected children and their phen-otypically normal mother. Blood samples were obtained simultaneously from all individuals on three separate occasions. Cultures were established and harvested by standard procedures. The slides were stained with giemsa and 50 cells were examined in detail from each culture. The only abnormality detected was a high frequency (P<<.0001) of chromatid and isochromatid breaks in both patients (0.24 and 0.22 breaks/cell, respectively) compared to that in 50 laboratory controls (0.02 breaks/cell). The frequency of breaks in the mother (0.08 breaks/cell), nearly one-third of that in her children, was still higher (P=.0001) than that in the controls.