Topic Completed: 1 September 2016

Minor changes: 15 December 2019

Copyright: 2016-2019,, Inc.

PubMed Search: PAX3 [title]

Angela M.Y. Chan, M.Sc.
Page views in 2020: 93
Page views in 2021 to date: 6
Cite this page: Enwere E, Chan A. PAX3. website. Accessed January 16th, 2021.
Definition / general
  • Paired box 3; transcription factor
  • Located on chromosome 2q35
  • Regulates tissues and organ development in embryonic development
  • Expressed in neural crest during embryonic development; regulates the expression of other genes that are involved in tissue and melanocytes, which regulate the pigment of hair, eye and skin color of the developing fetus
  • PAX3 is also required for normal development of craniofacial bones and myogenesis
Essential features
  • Expressed in early embryonic phases in dermatomyotome of paraxial mesoderm; therefore, it contributes to early striated muscle development
  • CDHS, paired domain gene HuP2, HuP2, splotch
Clinical features
  • Mutations including point mutation and truncation in PAX3 gene lead to Waardenburg syndrome types 1 and 3, which are genetic conditions that cause hearing loss and changes in pigmentation of the hair, skin and eyes (Hum Mol Genet 2000;9:1907)
  • PAX3 mutation at N47K leads to craniofacial-deafness-hand syndrome, which is characterized by distinctive facial features, hearing loss and abnormality of hand muscles
  • PAX3 / FOXO1A fusion gene is associated with alveolar rhabdomyosarcoma
    • This tumor mainly affects adolescents and young adults
    • This fusion gene increases the activity of PAX3 and prevents cell death; as a result, muscle cell growth becomes uncontrolled and leads to cancer of muscle (Oncogene 2005;24:1860)
  • Genetic sequencing on PAX3 is used clinically to diagnose Waardenburg syndrome
  • For list of laboratories that provide this testing please see the Genetic Testing Registry (GTR)
Prognostic factors
  • High expression of PAX3 in stromal cytoplasm of breast phyllodes tumor was associated with poorer overall survival (Histopathology 2014;64:807)
Case reports
Clinical images

Images hosted on other servers:

Abnormal pigmentation
in right iris and incomplete
left cleft lip caused by
mutation in PAX3 gene

Image showing patient
at 4 years of age with
freckles and premature gray
hair at 12 years of age

Microscopic (histologic) images

Images hosted on other servers:

Embryonal , alveolar and pleomorphic rhabdomyosarcoma

Cytology images

Images hosted on other servers:

PAX3 expression in melanocytic and melanoma cells

Positive stains
  • Placenta, brain, skin
Negative stains
  • Colon, kidney
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