Table 1 Previous studies that analyzed the DCDC2 deletion for association with dyslexia

Reference	Country	Sample	Type of analysis	Allele	Quantitative phenotype	P-value	Deletion Frequency
Meng et al., 2005	USA	153 nuclear families	Quantitative	Deletion+STR rare alleles	Homonym Choice	0.00002	8.5%
					Untimed PIAT Word Recognition	0.023
					Word Recognition	0.04
					OC	0.0035
					OC	0.0385
Harold et al., 2006	England	264 nuclear families	Quantitative	Deletion		Not associated	10%
		126 severe families subgroup			IWR	0.03	9%
					READ	0.04
					PA	0.05
	Wales	350 cases	Categorical	Deletion		Not associated	9% cases
		273 controls		Deletion+STR rare alleles		Not associated	9% controls
Brkanac et al., 2007	USA	191 trios	Quantitative	Deletion	SWE	0.05	7.5%
					Spelling	0.04
Ludwig et al., 2008	Germany	396 trios	Categorical	Deletion+STR rare alleles		Not associated	8.6%
Wilcke et al., 2009	Germany	72 cases	Categorical	Deletion		P<0.01	10% cases
		25 severe cases					8% severe cases
		184 controls					4% controls
Marino et al., 2012	Italy	303 nuclear families	Quantitative	Deletion	SWR	0.05	6%
				Deletion	PD	0.04
				STR allele 10	Memory Composite Score	0.00001
				Deletion+STR rare alleles	Memory Composite Score	0.00001
Powers et al., 2016	UK	89 cases	Categorical	Deletion	Severe RD	Not associated	8.3%
		4428 controls^a			Severe LI

Abbreviations: IWR, irregular word reading; LI, language impairment; OC, orthographic coding; PA, phonological awareness; PD, non-word reading; PIAT, Peabody individual achievement test; READ, single-word reading; RD, reading disability; SWE, sight word efficiency.
^aThe samples sizes were estimated by combining information from different studies;^{11, 12} these studies reported association between the 5 and 6 STR alleles with reading-related measures.

Quick links

Search