Chapter 27: Nursing Care of the Child With an Alteration in Genetics

The core concepts of heredity are established, defining terms such as gene, chromosome, allele, genotype, and phenotype. The discussion thoroughly examines inheritance patterns, starting with Mendelian or monogenic disorders, which include autosomal dominant inheritance (where the abnormal gene overshadows the normal one, exemplified by neurofibromatosis, and demonstrating a 50% risk for offspring) and autosomal recessive inheritance (requiring two mutant copies, leading to a 25% risk, seen in conditions like cystic fibrosis and sickle cell disease). X-linked disorders are differentiated, noting that X-linked recessive conditions like hemophilia disproportionately affect males due to their single X chromosome. Beyond single-gene defects, the chapter explores multifactorial inheritance, which involves multiple genes and environmental factors (e.g., cleft lip and cardiac defects), and complex nontraditional patterns like mitochondrial inheritance (maternally passed) and genomic imprinting (parental gene expression affects the phenotype, seen in Prader-Willi and Angelman syndromes). A significant portion is dedicated to chromosomal abnormalities, which often result from nondisjunction, leading to numerical issues like trisomies (e.g., Trisomy 21/Down syndrome, the most common abnormality associated with intellectual disability) and structural problems like translocations. Common chromosomal disorders, including the milder sex chromosome abnormalities like Turner and Klinefelter syndromes, are detailed, along with Fragile X syndrome, the most frequent inherited cause of intellectual disability. Furthermore, the text covers neurocutaneous disorders, highlighting Neurofibromatosis 1 and its hallmark café-au-lait spots, and inborn errors of metabolism (IEMs), which are often autosomal recessive enzyme deficiencies (e.g., PKU, Galactosemia) that require immediate dietary management post-newborn screening to prevent severe intellectual disability or death. Nurses are positioned as crucial providers in genetic evaluation, required to perform comprehensive assessments (including recognizing subtle signs like low-set ears or specific odors associated with IEMs) and facilitate genetic counseling, which is ideally provided preconceptionally to discuss risks, testing options (Amniocentesis, CVS), ethical issues, and psychosocial support.