dysgenesis

Dysgenesis is a medical term used to describe abnormal development of tissue, organ, or body part arising during embryogenesis. It denotes abnormal morphogenesis rather than complete absence, though it can contribute to anomalies that include malformations or underdeveloped structures. The concept is applied across organ systems and can be isolated to a single site or part of a broader syndrome.

Dysgenesis results from disruptions in developmental processes, which may be caused by genetic mutations, chromosomal abnormalities, environmental teratogens, or epigenetic factors. Alterations in signaling pathways that govern organ formation, such as HOX genes and pathways like SHH, WNT, or Notch, can misdirect tissue differentiation and growth. Vascular events, mosaicism, or interactions with surrounding tissues during gestation can also contribute. The presentation and severity vary widely depending on the affected organ and underlying cause.

Commonly discussed forms include gonadal dysgenesis, where the gonads fail to develop normally, seen in conditions such as Turner syndrome and Swyer syndrome. Dental dysgenesis refers to abnormal tooth development, including hypodontia or oligodontia and tooth malformations. Dysgenesis can involve the brain, kidneys, limbs, or other organs, and may occur as part of syndromic patterns or as an isolated defect.

Diagnosis relies on clinical examination, imaging studies, and laboratory testing, including hormonal panels and genetic testing when indicated. Management is organ-specific and may involve hormone replacement therapy for gonadal dysgenesis, fertility considerations, and dental or orthopedic interventions for other forms. Prognosis depends on the extent of the anomaly and associated health issues.

See also: agenesis, hypoplasia, congenital malformation.