In this study, we identified two novel compound heterozygous ATR mutations implicated in Seckel Syndrome (Patient P1ATR), one of which, c.151+4A > G (NG_008951.1), is known to affect splicing, while c.4995G > T results in an amino acid change, p.Lys1665Asn, of undetermined pathogenicity. Here, ATR is linked to microcephalic primordial dwarfism.