Constitutional mismatch repair deficiency in a healthy child: On the spot diagnosis?

Constitutional mismatch repair deficiency ( CMMRD ) is a rare, recessively inherited childhood cancer predisposition syndrome caused by biallelic germline mutations in one of the mismatch repair genes. The CMMRD phenotype overlaps with that of neurofibromatosis type 1 ( NF1 ), since many patients have multiple café‐au‐lait macules ( CALM ) and other NF1 signs, but no germline NF1 mutations. We report of a case of a healthy 6‐year‐old girl who...