Table 1.

Working terms for eight putative etiological subtypes of speech sound disorders of currently unknown origin and their genetic and/or environmental risk factors (distal causes) and associated affected processes (proximal causes).

No.	Type	Subtype	Abbreviation	Risk Factors	Processes Affected
1	Speech Delay	Speech Delay–Genetic	SD-GEN	Polygenic/Environmental	Cognitive-Linguistic
2		Speech Delay–Otitis Media with Effusion	SD-OME	Polygenic/Environmental	Auditory-Perceptual
3		Speech Delay– Developmental Psychosocial Involvement	SD-DPI	Polygenic/Environmental	Affective-Temperamental
4	Motor Speech Disorder	Motor Speech Disorder–Apraxia of Speech	MSD-AOS	Monogenic? Oligogenic?	Speech-Motor Control
5		Motor Speech Disorder–Dysarthria	MSD-DYS	Monogenic? Oligogenic?	Speech-Motor Control
6		Motor Speech Disorder-Not Otherwise Specified	MSD-NOS	Monogenic? Oligogenic? Polygenic? Environmental?	Speech-Motor Control
7	Speech Errors	Speech Errors-Sibilants	SE-/s/	Environmental	Speech Attunement
8		Speech Errors-Rhotics	SE-/r/	Environmental	Speech Attunement