#congenital anomaly

• Acardiac — Lacking a heart, or possessing a rudimentary, completely non-functional heart. In neonatology and fetal medicine, the term describes an 'acardiac fetus' (or acardiac twin), an extremely rare congenital anomaly occurring exclusively in monochorionic twin pregnancies due to Twin Reversed Arterial Perfusion (TRAP sequence). In this condition, the malformed fetus survives in utero only because it receives blood pumped by the heart of its healthy co-twin (the pump twin).
• Adenectopia — A congenital anomaly or abnormal, faulty positioning of a gland or a lymph node outside its usual anatomical site. This structural phenomenon occurs during defective embryonic development, when the glandular tissue migrates incorrectly, potentially functioning normally or generating complications due to compression on neighboring organs.
• Agenosomia — A severe congenital malformation of a teratological nature, characterized by the incomplete development or partial to total absence of external genital organs and the lower abdominal wall, frequently associated with visceral eventration. This severe structural anomaly is clinically investigated within fetal pathology and is commonly considered incompatible with long-term extrauterine survival.
• Aglossia — An extremely rare congenital malformation characterized by the total anatomical and structural absence of the tongue. This embryonic developmental anomaly severely impairs the vital functions of deglutition, respiration, and mastication, as well as the functional capacity to articulate speech sounds and spoken language.
• Amastia — A rare congenital anomaly characterized by the complete unilateral or bilateral absence of breast tissue, areola, and nipple. Clinically, this embryonic development malformation results from the failure of the mammary ridge to proliferate during early gestation.
• Amastia — An alternative spelling variant or adapted graphical form in medical literature for 'amastie' (amastia); a rare congenital anomaly characterized by the complete unilateral or bilateral absence of breast tissue, areola, and nipple.
• Ankyloblepharon — A rare ophthalmological condition, either congenital or acquired (following chemical burns, trauma, or severe inflammation), characterized by the partial or total fusion of the margins of the upper and lower eyelids along the palpebral fissure, leading to a narrowing of the eye opening or the complete inability to open the affected eye.
• Anencephalic — A medical term describing a fetus, newborn, or individual affected by anencephaly, a severe congenital malformation characterized by the partial or total absence of the brain, meninges, and skull bones. As an adjective, it refers to any biological structure or organism exhibiting this profound developmental defect of the anterior neural tube.
• Anencephalic — Pertaining to anencephaly or relating to this severe congenital malformation; characteristic of an organism partially or totally lacking a brain and the bony elements of the cranial vault. The term clinically, structurally, or pathologically describes the manifestations and tissues associated with this major neural tube defect.
• Anonychia — A rare congenital anomaly or acquired pathological condition characterized by the complete absence of one or more nails from the fingers or toes. This structural defect stems from a developmental failure of the nail matrix during the fetal stage or its subsequent destruction due to severe trauma, infections, or systemic dermatological diseases, frequently serving as a clinical marker within complex genetic syndromes such as ectodermal dysplasia.
• Anorchia — A rare congenital malformation characterized by the complete structural absence of both testes in an individual with a male karyotype (46,XY). This embryonic developmental anomaly, also known as congenital testicular regression, occurs due to the early degradation or involution of the gonads during intrauterine life, requiring close endocrine monitoring and long-term hormone replacement therapy starting at puberty.
• Anovaria — A rare pathological condition or congenital anomaly characterized by the complete structural absence or total underdevelopment of both ovaries in an individual with a female phenotype. This severe anomaly of the reproductive system causes a drastic deficiency of sex hormones (estrogens and progesterone), leading to immediate clinical effects such as primary amenorrhea, failure to achieve puberty, and definitive sterility, requiring endocrine replacement therapy.
• Arachnodactyly — A congenital anomaly characterized by the excessive length, slenderness, and unusual flexibility of the fingers and toes, causing them to assume an elongated appearance reminiscent of a spider's legs. It represents a major clinical sign and a foundational diagnostic criterion for hereditary connective tissue disorders, most frequently associated with Marfan syndrome or Loeys-Dietz syndrome.
• Arteriectopia — A rare congenital or acquired medical condition representing the structural anomaly of positioning or displacement of an artery outside its normal anatomical pathway or outside its usual place within tissues. This ectopic localization can be asymptomatic or can generate complications due to mechanical compression exerted on neighboring organs, nerves, or structures, requiring advanced imaging monitoring to prevent surgical risks.
• Astomia — An extremely rare congenital malformation characterized by the complete absence of the oral orifice (the mouth). This severe structural anomaly of embryonic development requires complex and immediate postnatal surgical intervention to allow respiration and feeding of the newborn, being often associated with other developmental changes in the facial structure.