We report on a familial case of small 17p13.3 chromosomal deletion.Conventional karyotyping revealed a der(17) in a family.HumanCytoSNP-12 Chip analysis identi ed 1.68 Mb deletion in 17p13.3 and 9.74 Mb duplication from 10q26.13 to q26.3 in the proband and the infant, which was reported for the rst time here.17p13.3 deletion is a well-delineated chromosomal syndrome with characteristic clinical features, while chromosome 10q duplication is a rare genetic condition.None cases of monosomy 17p/trisomy 10q have been previously described.The 17p13.3 deletion, overlaps with the critical region for Miller-Dieker syndrome and contains YWHAE and CRK gene, but not PAFAH 1 B1.The duplication region extending from 10q26.13 to 10q26.3 was previously identi ed as a critical region for the 10q duplication syndrome.These results suggested that the apparently balanced de novo translocations could produce cryptic deletions or duplications, and the precise mapping of the abnormal area may improve clinical management.