agênese

Agênese is a term used in Portuguese-language medical literature to denote agenesis, the congenital absence of an organ or structure due to failure of development during embryogenesis. The word derives from the Greek genesis with the a- prefix indicating negation, and it is used to describe a range of developmental abnormalities.

In medicine, agenesis refers to the complete absence of an organ or tissue at birth. It is distinct from aplasia (failure of an organ to develop in the presence of a primordial tissue) and hypoplasia (underdevelopment of an organ). Agenesis can involve various organ systems and may occur in isolation or as part of a syndrome. Common examples include renal agenesis (absence of one or both kidneys), bilateral renal agenesis being typically incompatible with life and associated with Potter sequence; agenesis of the corpus callosum (absence of the primary bridge between the brain hemispheres); and limb agenesis (absence of limbs).

Diagnosis is usually achieved through prenatal or postnatal imaging, such as ultrasound, magnetic resonance imaging, or computed tomography, and may involve genetic testing to identify contributing mutations. Management depends on the organ involved and on associated anomalies; some cases require supportive care or prosthetic or transplant strategies, while unilateral forms may have relatively favorable outcomes.

Tooth agenesis, often discussed in dental contexts, refers to the congenital absence of one or more teeth and is described in relation to syndromic or non-syndromic patterns. It is commonly classified clinically as hypodontia or oligodontia, depending on the number of missing teeth.

See also: agenesis, aplasia, hypoplasia, embryology, dental agenesis.

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