Germline CDKN2A mutations are rare in child and adolescent cutaneous melanoma

Early-onset melanoma under the age of 20 years is still a rare disease but has an increasing incidence. The aim of this study was to determine whether CDKN2A germline mutations are present in patients diagnosed with childhood/adolescent melanoma. From the Swedish Cancer Register we identified 60 patients with a diagnosis of cutaneous malignant melanoma before the age of 20 years. A medical history including information on self-reported melanoma heredity was obtained, a physical examination was performed by a dermatologist, and the histopathology slides were reviewed. A blood test was obtained for analysis of germline CDKN2A exon 1 and exon 2 mutations by DNA sequencing. We found only one germline CDKN2A mutation with functional significance, which was an exon 1 missense mutation resulting in a proline-to-leucine substitution in codon 48. This mutation was seen in a patient belonging to a previously reported kindred with hereditary melanoma where this particular germline CDKN2A mutation had been identified. Thus, in the large majority of cutaneous melanoma in childhood/adolescence, any underlying genetic alterations have yet to be identified.