Table 3.

Concordance Between 1p/19q Fluorescence In Situ Hybridization and PCR-Based Microsatellite Loss of Heterozygosity Data Is Further Refined by 10q Status

1p/19q FISH		10q status	1p/19q PCR microsatellite-based LOH		% FISH-PCR concordance
			codeleted	Intact
original criteria	codeleted	10q intact	52	7	88.1
		10q LOH	4	13	23.5
	intact	10q intact	0	13	100.0
		10q LOH	1	8	88.9
modified criteria	codeleted	10q intact	49	5	90.7
		10q LOH	4	10	28.6
	intact	10q intact	3	15	83.3
		10q LOH	1	11	91.7

Ninety-eight World Health Organization grade II and III oligodendrogliomas were tested for 1p/19q codeletion by FISH and PCR-based LOH analysis and for 10q deletion. Both by original and more stringent modified criteria, if a case was 1p/19q-codeleted and intact for 10q, PCR analysis also called the case codeleted about 90% of the time. If a case was called 1p/19q-codeleted by FISH yet had 10q LOH, PCR analysis called the same tumor negative for codeletion over 70% of the time. If a tumor was 1p/19q intact by either original or modified FISH criteria and also 10q intact, PCR analysis also called it 1p/19q intact 80–100% of the time; the presence of 10q LOH did not appreciably change that proportion (about 90%). FISH = fluorescence in situ hybridization; LOH = loss of heterozygosity; PCR = polymerase chain reaction.