Monogénes

Monogénes, or monogenic conditions, are diseases or traits caused by mutations in a single gene. The term is used in genetics to distinguish these disorders from polygenic or multifactorial conditions that involve many genes and environmental factors. Monogenic disorders can be inherited in Mendelian patterns and may present at any age, from infancy to adulthood.

Inheritance of monogenic diseases follows specific patterns: autosomal dominant, autosomal recessive, X-linked dominant or recessive, and, less commonly, mitochondrial inheritance. In autosomal dominant conditions, a single mutated copy suffices to produce the disorder. In autosomal recessive conditions, two copies are usually needed. X-linked disorders are linked to genes on the X chromosome and often affect males more severely. Some cases are de novo mutations, arising anew in a family without a prior history.

Common examples include cystic fibrosis (CFTR, autosomal recessive), phenylketonuria (PAH, autosomal recessive), Huntington’s disease (HTT, autosomal dominant), sickle cell disease (HBB, autosomal recessive), and Duchenne muscular dystrophy (DMD, X-linked recessive). These conditions illustrate the diversity of clinical presentations, penetrance, and expressivity seen in monogenic diseases.

Diagnosis typically relies on genetic testing, including targeted gene panels, exome, or genome sequencing, often complemented by family history and newborn screening where applicable. Management emphasizes symptom relief and disease-specific therapies; some monogenic disorders may benefit from dietary interventions, enzyme replacement, or emerging gene therapies.

Genetic counseling is integral, addressing inheritance risk, reproductive options, and implications for relatives. Ongoing research in gene editing, RNA-based therapies, and personalized medicine continues to expand the options for diagnosis, treatment, and prevention of monogenic diseases.