#congenital

• From the origin — A Latin phrase meaning 'from the origin' or 'from the very beginning'. In medical genetics and embryology, it is used to describe a chromosomal anomaly, congenital malformation, or metabolic disorder present in the organism's biological framework since the moment of conception (ab origine), as opposed to conditions acquired later in life.
• Ablepharia — The congenital partial or total absence of eyelids, studied in physical anthropology, comparative zoology, and developmental biology to understand evolutionary genetic mutations and structural anomalies in vertebrates. In paleoanthropological and animal population dynamics studies, this morphological trait is analyzed as an extreme recessive feature that affects adaptability and visual apparatus protection in environments with intense solar exposure.
• Abrachia — An extremely rare congenital malformation characterized by the complete absence or rudimentary development of the arms (upper limbs) in a fetus or developing organism; a severe anatomical anomaly within the category of limb agenesis, similar to or closely related to amelia and congenital abrachia.
• Abrachiocephalus — A teratological monster, fetus, or organism with severe congenital malformations, characterized by the simultaneous absence of both arms and the head, or by the abnormal and rudimentary fusion of cephalic structures in the complete absence of upper limbs; (adjectival) presenting the anatomical features of this embryonic developmental anomaly.
• Abrachiocephaly — A complex and extremely severe congenital malformation characterized by the simultaneous absence of both the head (acephalia) and both upper limbs (abrachia) in a fetus or developing organism; an early embryonic developmental anomaly, incompatible with life, studied within classical and experimental teratology.
• 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).
• Acardia — A congenital absence of the heart or a complete cessation in the ontogenetic development of the cardiac structure in a fetus. This severe structural anomaly is incompatible with independent extrauterine life and is documented almost exclusively within monochorionic multiple pregnancies with asymmetric development (TRAP sequence), where the affected fetus's blood circulation is maintained solely by its twin's heart through placental vascular anastomoses.
• Acrania — A highly severe congenital structural defect characterized by the partial or total absence of the cranial vault (calvaria), while the skull base and facial bones are partially developed.
• Adactyly — A rare congenital malformation characterized by the total or partial absence of fingers or toes. This structural anomaly of embryonic development can occur in isolation or as part of a complex malformativ syndrome, determined by genetic mutational factors or external teratogenic insults suffered by the embryo during the first weeks of pregnancy.
• 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.
• Agastria — An extremely rare congenital malformation consisting of the total absence of the stomach from birth; by extension, the anatomical and clinical state resulting from a total gastrectomy (complete surgical removal of the organ). Structurally, this condition disrupts the normal digestive pathway, requiring a surgical restructuring of the tract by directly connecting the esophagus to the jejunum (esophagojejunostomy) and a strict nutritional regimen.
• Agenetic — Relating to agenesis; characterized by the congenital absence of an organ, tissue, or body part, caused by the failure of its development during embryonic life. In a clinical sense, it describes an organism, anatomical segment, or process affected by this severe structural development anomaly.
• Agenesis — The congenital absence of an organ, tissue, or body part, caused by the failure of its development during embryonic life. Unlike aplasia, where the embryonic bud exists but fails to fully mature, in this severe structural anomaly the initial blueprint of the organ is completely missing from the genetic profile.
• Agenitalism — An extremely rare clinical condition characterized by the total congenital absence of internal and external genital organs or by the complete lack of hormonal secretion from the gonads (severe sexual infantilism). This endocrine and organic structural disorder profoundly affects the development of secondary sexual characteristics and reproductive capacity.
• 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.
• Agenesis — A rare congenital malformation characterized by the complete absence, structural underdeveloped state, or congenital lack of an organ, tissue, or body part since the intrauterine development period. The phenomenon is caused by genetic errors or teratogenic factors manifesting during the early phases of organogenesis.
• 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.
• Agonadism — A highly rare congenital medical condition characterized by the complete structural and functional absence of gonads (testes or ovaries), caused by an anomaly in early embryonic development; it results in a lack of sex hormones and requires life-long hormone replacement therapy.
• Allochezia — A pathological symptom or condition manifested by the defecation from an opening other than the normal anus, or by the expulsion through the anus of foreign matter or objects instead of ordinary feces. This clinical phenomenon reflects severe structural anomalies, complex rectal fistulas, or congenital malformations of the lower digestive tract.
• 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.