See Conditions by First Letter (X)
- X-linked Adrenal Hypoplasia Congenita
- X-linked Agammaglobulinemia
- X-Linked Combined Immunodeficiency Diseases
- X-linked Congenital Stationary Night Blindness
- X-linked Hypohidrotic Ectodermal Dysplasia
- X-linked Ichthyosis
- X-linked Lymphoproliferative Syndrome
- X-linked Mental Retardation and Macro-orchidism
- X-linked Severe Combined Immunodeficiency
- Xanthomatosis
- Xanthomatosis, Cerebrotendinous
- Xeroderma Pigmentosum
- Xerophthalmia
- Xerostomia
- XYY Karyotype