Chromosomal Disorders
Down syndrome (Trisomy 21): most common chromosomal disorder, intellectual disability, characteristic features, congenital heart defects, increased leukemia risk, early Alzheimer disease. Turner syndrome (45,X): females, short stature, webbed neck, ovarian failure, cardiac (coarctation). Klinefelter syndrome (47,XXY): males, tall, gynecomastia, small testes, infertility, learning disabilities. Trisomy 18 (Edwards), Trisomy 13 (Patau): severe, usually fatal in infancy. Fragile X: most common inherited intellectual disability, autism features.
Single-Gene Disorders
Autosomal recessive: cystic fibrosis (CFTR, thick mucus, pancreatic insufficiency, infertility in males), sickle cell disease (HbS, vaso-occlusion), PKU (phenylalanine metabolism, intellectual disability if untreated, dietary treatment). Autosomal dominant: Huntington disease (CAG repeat, chorea, cognitive decline, psychiatric), Marfan syndrome (fibrillin, tall, lens dislocation, aortic dissection), familial hypercholesterolemia (LDL receptor, premature CAD). X-linked: hemophilia, Duchenne muscular dystrophy, fragile X.
Nursing Management
Assessment: growth, development, complications (cardiac, respiratory, intellectual). Screening: newborn, prenatal, carrier. Management: condition-specific (CF — airway clearance, enzymes, nutrition; sickle cell — hydration, pain, immunization; PKU — phenylalanine-restricted diet). Genetic counseling: recurrence risk, prenatal options. Family support: education, resources, support groups. Multidisciplinary care: genetics, cardiology, pulmonology, neurology, developmental. Transition to adult care. Lifespan considerations. Advocate: inclusion, anti-discrimination, accessibility. Advance directives for adult-onset conditions.
Important Notes
- Down syndrome patients have increased risk of leukemia and early-onset Alzheimer disease — monitor and educate families.
- Cystic fibrosis is the most common lethal autosomal recessive disorder in Caucasians — carrier frequency 1 in 25.
Clinical Tips
- Marfan syndrome patients need echocardiographic surveillance for aortic root dilation — aortic dissection is the leading cause of death.
- Phenylketonuria (PKU) requires lifelong phenylalanine-restricted diet — maternal PKU causes fetal intellectual disability even if fetus does not have PKU.
Summary
Common genetic disorders include chromosomal (Down, Turner, Klinefelter) and single-gene (CF, sickle cell, Huntington, Marfan) — nursing requires screening, condition-specific management, and family support.
