It is supposed to be caused by defects of genes on chromosome3 and 18. One form of Seckel syndrome can be caused by mutation in the gene encoding the ataxia telangiectasia and Rad3 related protein (ATR) which maps to chromosome 3q22.1-q24. This gene is central in the cell's DNA damage response and repair mechanism.
^Harper RG, Orti E, Baker RK (May 1967). "Bird-beaded dwarfs (Seckel's syndrome). A familial pattern of developmental, dental, skeletal, genital, and central nervous system anomalies". J. Pediatr.70 (5): 799–804. doi:10.1016/S0022-3476(67)80334-2. PMID6022184.