Constitutional mismatch repair deficiency syndrome-4 (MMRCS4) is a very rare autosomal recessive childhood cancer predisposition syndrome characterized by early-onset leukemia/lymphoma, brain tumors, colorectal/gastrointestinal carcinomas, and other rare malignancies, including rhabdomyosarcomas. Cafe-au-lait spots are usually present (De Vos et al. 2006).
To date, approximately 200 affected individuals have been described in the literature, presenting with a total of over 320 different neoplasms, including hematologic neoplasms (24%), brain/CNS tumors (35%), and colorectal or other Lynch syndrome-associated tumors (38%).