Fanconi anemia complementation group S is an autosomal recessive disorder with developmental delay, short stature, microcephaly, and dysmorphic features. Patients exhibit defective DNA repair, increased chromosomal breakage under stress, and may have radial ray anomalies, anemia, and cancer predisposition. The disease is linked to mutations in the BRCA1 gene on chromosome 17q21, leading to hypersensitivity to DNA-damaging agents and chromosomal instability.