Rearrangements involving the ALK gene were identified in a variety of cancers, 
including paediatric tumour neuroblastoma where presence of ALK expression is 
also associated with adverse prognosis. Microarrays data indicate that ALK is 
expressed in another paediatric tumour - medulloblastoma. Therefore, we 
investigated if the ALK gene is mutated in medulloblastoma and performed 
simultaneously the molecular profiling of tumours. Tumours from sixty-four 
medulloblastoma patients were studied for detection of ALK alterations in exons 
23 and 25 using Sanger method. The molecular subtypes of tumours were identified 
by detection of mutations in the CTNNB1 gene, monosomy 6 and by 
immunohistochemistry using a panel of representative antibodies. Among three ALK 
variants detected two resulted in intron variants (rs3738867, rs113866835) and 
the third one was a novel heterozygous variant c.3595A>T in exon 23 identified 
in the WNT type of tumour. It resulted in methionine to leucine substitution at 
codon position 1199 (M1199L) of the kinase domain of ALK protein. Results of 
analysis using three in silico algorithms confirmed the pathogenicity of this 
single nucleotide variation. The same gene alteration was detected in both 
patient and maternal peripheral blood leukocytes indicating an inherited type of 
the detected variant. Presence of ALK expression in tumour tissue was confirmed 
by immunohistochemistry. The tumour was diagnosed as classic medulloblastoma, 
however with visible areas of focal anaplastic features. The patient has been 
disease free for 6 years since diagnosis. This is the first evidence of an 
inherited ALK variant in the WNT type of medulloblastoma, what altogether with 
presence of ALK expression may point towards involvement of the ALK gene in this 
type of tumours.