- Campomelic dysplasia
- Canavan disease
- Cancer
- Cardiofaciocutaneous syndrome
- Carnitine palmitoyltransferase deficiency
- Carpenter syndrome
- Celiac disease
- Central core disease
- Cerebral palsy
- Charcot-Marie-Tooth disease
- Charge Syndrome
- Chediak-Higashi syndrome
- Chondrosarcoma
- Choroideremia
- Chromosomal abnormalities
- Chromosome
- Cleft lip and palate
- Cleidocranial dysplasia
- Clubfoot
- Cockayne syndrome
- Coffin-Lowry syndrome
- Coffin-Siris syndrome
- Cohen syndrome
- Coloboma
- Color blindness
- Cone-rod dystrophy
- Congenital adrenal hyperplasia
- Congenital heart disease
- Congenital hypothyroid syndrome
- Conjoined twins
