The clinical and karyotypic analysis of a 7 years old girl with Pyle's disease are reported. Clinically the patient presented an unusual neuropsychic involution and pyramido-extrapyramidal symptomatology. The karyotypic analysis showed chromosomal breakage em 12% of the cells. However the genealogical study of the patient pointed towards a recessive disease. Various hypothesis of chromosomal breakage in recessive diseases are discussed, the possibility of secondary breakage being emphasized.