Analysis of the effect of type of mutation on chromosomal instability and clinical severity of patients' phenotype. Box plots are shown representing median ± maximum-minimum values. (A) Spontaneous chromosome fragility indicated by Spontaneous Chromosome Fragility Index (SCFI = breaks per cell × percentage cells with breaks). (B) DEB-induced chromosome fragility as indicated by Chromosome Fragility Index (CFI = breaks per multiaberrant cell × percentage of cells with breaks). (C) Age in years at onset of hematologic disease. (D) Number of congenital malformations.