Genetic Disorders
Chapter 33: Genetic Disorders
Overview of Genetic Disorders
Definition: Genetic disorders are conditions caused by abnormalities in a person’s genetic material.
Categories of Genetic Disorders:
Monogenic (Mendelian) Disorders:
Caused by mutations in a single gene.
Types include:
Autosomal dominant
Autosomal recessive
X-linked dominant
X-linked recessive
Multifactorial Disorders:
Caused by a combination of genetic and environmental factors.
Nontraditional Inheritance:
Do not follow typical inheritance patterns.
Example: Mitochondrial disorders, usually inherited from the biological mother.
Chromosomal Disorders:
Result from abnormalities in chromosome number or structure.
Can involve structural or numeric abnormalities.
Inheritance patterns can be erratic, often due to errors in sperm or egg formation.
General Nursing Interventions for Genetic Disorders
Emotional and Psychosocial Support:
Recognize and maintain a functional support system for the patient and family.
Provide accurate, thorough explanations to help reduce anxiety.
Teach caregivers how to advocate for their children’s needs.
Promotion of Growth and Development:
Encourage participation in early intervention programs.
Offer age-appropriate toys to support developmental milestones.
Prevention and Management of Complications:
Monitor for increased risk of health complications, particularly cardiac issues.
Be aware of common problems like hearing and vision impairments.
Nutritional Support:
Assess nutritional needs; may require enteral nutrition or adaptive devices to assist with feeding.
Fragile X Syndrome
Definition: An inherited genetic condition recognized as the most common cause of intellectual disability.
Prevalence: More severe symptoms often manifest in boys due to having only one X chromosome.
Inheritance Pattern: X-linked dominant.
Manifestations Include:
Minor dysmorphic features
Developmental delay
Physical characteristics such as a large head, long face, prominent ears, flat feet, enlarged testicles, hypermobile joints.
Sensory processing issues and behavioral problems.
Diagnosis: Confirmed through genetic testing.
Treatment: Involves developmental therapies and interventions; there is currently no cure but individuals can have a normal life span.
Questions and Answers on Fragile X Syndrome
Question: Does Fragile X Syndrome only manifest in people assigned male at birth?
Answer: False. It can also affect individuals assigned female at birth despite being more common in males due to the inheritance pattern.
Phenylketonuria (PKU)
Definition: A rare inherited metabolic disorder caused by an inborn error of metabolism detected through newborn screening.
Inheritance Pattern: Autosomal recessive.
Pathophysiology: Results from a deficiency of a liver enzyme, leading to the inability to process phenylalanine.
Consequences: High levels of phenylalanine can lead to irreversible brain damage.
Manifestations:
Irritability
Vomiting after protein feedings
Musty body odor
Increased reflex actions
Seizures
Skin rashes
Microcephaly and developmental delays.
Treatments: Require meal plans low in phenylalanine and regular level testing of blood phenylalanine concentrations.
Questions and Answers on PKU
Question: What diet should a child with PKU adhere to?
Options:
A. Low protein
B. Low calcium
C. Low iron
D. Low calorie
Answer: A. Low protein. Children with PKU must avoid high-protein foods including dairy, eggs, meat, poultry, fish, nuts, beans, and foods containing aspartame to prevent the accumulation of phenylalanine.
Trisomy 13
Also Known As: Patau syndrome.
Description: A non-inherited chromosomal condition characterized by three copies of chromosome 13 in each cell.
Manifestations Include:
Cleft lip and palate
Extra digits (polydactyly)
Clenched hands
Close-set eyes
Hernias
Low-set ears
Scalp defects
Single palmar crease
Limb abnormalities
Microcephaly
Undescended testicles.
Diagnosis: May be achieved through prenatal testing.
Survival Rate: Most infants do not survive past the first month of life.
Common Complications:
Apnea
Deafness
Heart failure
Seizures
Intellectual disability
Hemorrhagic abnormalities
Vision problems.
Interventions: Focus on symptomatic care for the infant and supportive care for the family, including connecting them with support organizations.
Trisomy 18
Also Known As: Edwards syndrome.
Description: Typically a non-inherited chromosomal condition characterized by three copies of chromosome 18 in each cell.
Manifestations Include:
Intrauterine growth restriction
Low birth weight
Small head and jaw
Low-set ears
Short eyelid fissures
Clenched and overlapping digits
Hypotonia and a short sternum
Narrow hips with limited abduction.
Survival Rate: Most affected infants do not survive past one year of age, with a high incidence of congenital heart disease and respiratory dysfunction.
Interventions: Mainly focus on repairing or palliating life-threatening anomalies.
Complications: Similar to Trisomy 13, with a general focus on symptomatic care and family support.
Trisomy 21
Also Known As: Down syndrome.
Description: A chromosomal condition caused by random events during the formation of reproductive cells, resulting in three copies of chromosome 21 in each cell.
Manifestations:
Flattened bridge of the nose
Almond-shaped eyes
Cardiac defects
Hearing and vision impairments
Increased mobility of the cervical spine.
Diagnosis: Utilizes prenatal tests such as ultrasound, amniocentesis, chorionic villus sampling, and percutaneous umbilical blood sampling.
Treatments for Trisomy 21
Monitoring: Assess for developmental delay using appropriate milestones specific to children with Trisomy 21.
Referrals: Encourage referrals to early intervention and various therapies, including speech, occupational, and physical therapy.
Complications:
Heart defects
Gastrointestinal abnormalities
Soft-tissue and skeletal changes
Hypothyroidism
Atlantoaxial instability of the first and second cervical vertebrae
Autoimmune disorders
Increased susceptibility to infectious diseases.
Diagnostics: Regular assessments include echocardiograms, abdominal ultrasounds, laboratory testing, sleep apnea tests, cervical x-rays, and thyroid hormone level evaluations.
Questions and Answers on Trisomy 21
Question: Is there a modified list of developmental milestones that should be implemented in the treatment of children with Trisomy 21?
Answer: True. A modified developmental milestone list should be used to assess proper development and account for delays due to Trisomy 21, guiding when early intervention is necessary.
Turner Syndrome
Definition: A chromosomal condition affecting only individuals assigned female at birth, resulting from the complete or partial absence of the second sex chromosome.
Classifications:
Monosomy X
X chromosome mosaicism.
Manifestations:
Difficulty with nonverbal communication skills
Executive functioning challenges
Physical characteristics including a wide or webbed neck, broad chest with widely spaced nipples
Slowed growth and short stature
Cardiac defects
Edema of hands and feet.
Common Complications:
Chronic middle ear infections leading to hearing loss
Autoimmune disorders
Infertility
Abnormalities affecting the heart, liver, and kidneys.
Treatment Options: Involve growth hormone and estrogen therapy to address symptoms and health requirements.
Klinefelter Syndrome
Definition: A sex chromosomal aneuploidy in individuals assigned male at birth characterized by the presence of an extra X chromosome.
Recognition: Rarely recognized prior to puberty; some individuals may remain undiagnosed throughout life.
Primary Manifestation: Testicular dysfunction commonly results in hypogonadism, cryptorchidism, and reduced testicular size during infancy.
Associated Mental Health Issues: Learning disabilities, anxiety, and signs of immaturity are often prevalent.
Monitoring and Treatment:
Assess and monitor testosterone, luteinizing hormone (LH), and follicle-stimulating hormone (FSH) levels.
Replacement therapy with testosterone is recommended to mitigate symptoms.
Speech therapy may be necessary due to delayed language development.