Table 2.

Total number of single nucleotide variants and insertion-deletions flagged by the clinical reporting workflow in all 1133 probands (in the November, 2013 version of DDG2P) compared with the number of variants that would have been flagged in the same probands in the absence of parental data

	Family-trio analysis		Proband-only analysis
	Inherited	De novo*
Autosomal dominant	473	193	9529
Autosomal recessive (homozygotes)	83	0	191
Autosomal recessive (compound heterozygotes)†	341	6	1071
X-linked dominant	38	21	269
X-linked recessive	322	15	387
Total	1257	235	11 447

Inherited variants in autosomal dominant DDG2P genes account for the main difference, in which only de novo variants and those inherited from an affected parent are likely to be of clinical interest. Around 90% of flagged variants were predicted to be missense point mutations. DDG2P=Developmental Disorders Genotype-to-Phenotype database.

^*Before secondary validation by targeted Sanger sequencing.

^†Two or more likely pathogenic variants in different copies of the same gene, counted once per compound variant.