Seckel syndrome is a type of microcephalic primordial dwarfism that is characterized by a proportionate dwarfism of prenatal onset, a severe microcephaly, a typical dysmorphic face (bird-like), and mild to severe intellectual disability.

Elevated rate of chromosomal breakage or interchanges occurring either spontaneously or following exposure to various DNA-damaging agents. This feature may be assayed by treatment of cultured lymphocytes with agents such as chemical mutagens, irradiation, and alkylating agents.