Albinism (overview) E70.3

Pearson K et al. 1911

Albinism is the genetically determined absence of pigment. Clinically, it is a group of genetically different diseases characterized by a generalized or partial loss of pigment in the skin, hair and eyes (oculocutaneous albinism - OCA) or only in the eyes (ocular albinism) (note: only albinism type IA and generalized vitiligo show a complete loss of pigment). The underlying cause is a congenital, mostly autosomal recessive inherited disorder of melanin synthesis (defect in tyrosine kinase) with a normal intraepidermal melanocyte count. The combination of pigment disorders on the skin, hair and eyes is referred to as oculocutaneous albinism, the localized infestation of the eyes as ocular albinism.

The following entities can be distinguished:

• Oculocutaneous albinism (OCA types 1-8)
• Ocular albinism (dermatologically irrelevant): 5 forms with varying degrees of iris depigmentation. Additionally photophobia, possibly nystagmus, strabismus, hypoplasia of the central fovea.
• Further, rare, syndromatic forms of albinimus (also known as "albinoidism") with generalized, pronounced hypopigmentation and additional organ manifestations that are decisive for morbidity and prognosis:
  • Hermansky-Pudlak syndrome
  • Chédiak-Higashi syndrome
  • Cross syndrome
  • Griscelli syndrome

  • Primary immunodeficiency syndrome due to Lamtor2 defect

There are now eight documented OCA types (OCA1-8) with non-syndromic features. Molecular studies have identified seven genes associated with the OCA phenotype:

• TYR gene
• OCA2 gene
• TYRP1 gene
• SLC45A2 gene
• C24A5 gene
• C10orf11 gene
• DCT gene

and a locus(OCA5) in consanguineous and sporadic albinism.

Albinism must be distinguished from piebaldism (known as leucism in veterinary medicine), in which melanocytes are completely absent in the depigmented areas due to gene mutations (mutations in the KIT (see kit below) and SLUG (SNAI2 - snail homolog 2 transcription factor) gene (Saleem MD et al. 2019) have been proven).

1. Böhm M (2015) Differential diagnosis of hypomelanosis. Dermatologist 66: 945-958
2. Bohn G et al. (2007) A novel human primary immunodeficiency syndrome caused by deficiency of endosomal adaptor protein p14. Nature Med 13: 38-45.
3. Pearson K et al. (1911) a monograph on albinism in men; Draper`s company reseach memoirs, Biometric series VI. Dula, London
4. Saleem MD et al. (2019) Biology of human melanocyte development, Piebaldism, and Waardenburg syndrome. Pediatr Dermatol 36:72-84.
5. Schiefermeier N et al. (2014) The late endosomal p14-MP1 (LAMTOR2/3) complex regulates focal adhesion dynamics during cell migration. J Cell Biol 205:525-540.