Table 4. Association of clinical and biological features with differential gene and exon expression.

Class	No. of differentially expressed genes	No. of differentially expressed exons	No. of alternatively used exons
Stage	1277	11 805	41
Age	472	5230	0
MNA	2278	23 382	256
Survival	3936	34 475	306
Relapse	1343	13 165	31
TrkA	2748	32 681	471

Abbreviation: INSS=International Neuroblastoma Staging System.

INSS stage (stage IV vs non-stage IV), age at diagnosis (age, < or >12 months at diagnosis), MYCN status (MNA, MYCN amplified vs MYCN single copy), outcome (survival or relapse refer to OS and relapse-free survival) or NTRK1 expression (NTRK1/TrkA expression < or > median) were analysed using Welch's t-test for significant association with gene (no. of differentially expressed genes) or exon (no. of differentially expressed exons) expression. To identify alternative exon use only genes without significant expression changes between the group analysed were considered and then exons were identified that were significantly differentially expressed (no. of alternatively used exons).