Table 3.

Phenotype definitions for ALSPAC analyses

	Phenotype definition
Reading (RD)
Severe RD	2 Standard deviations below sample mean on the phoneme deletion task
Moderate RD	1 Standard deviation below sample mean on SWR7, SNR, and SWR tasks
Language (LI)
Severe LI	2 Standard deviations below sample mean on either WOLD and/or NWR tasks
Moderate WOLD	1.5 Standard deviations below sample mean on the WOLD task
Moderate NWR	1.5 Standard deviations below sample mean on the NWR task
Cognition (IQ)
Total IQ	Quantitative performance on WISC Total IQ task
Verbal IQ	Quantitative performance on WISC Verbal IQ task
Performance IQ	Quantitative performance on WISC Performance IQ task