public int intronSize(int intronNum) {
		if (intronNum >= (numChilds() - 1)) return -1;
		ArrayList<Exon> exons = (ArrayList<Exon>) sortedStrand();
		Exon exon = exons.get(intronNum);
		Exon next = exons.get(intronNum + 1);
		return (isStrandPlus() ? (next.getStart() - exon.getEnd()) : (exon.getStart() - next.getEnd())) - 1;
	}