SNP Shot: Genomic Insights

Familial dysautonomia is a genetic condition affecting the development and survival of specific nerve cells. This disorder disrupts the function of cells within the autonomic nervous system, which governs involuntary bodily processes like digestion, breathing, tear production, and blood pressure and body temperature regulation. It also impacts the sensory nervous system, responsible for senses such as taste and the perception of pain, heat, and cold. Familial dysautonomia is also known as hereditary sensory and autonomic neuropathy type III.

Symptoms of this condition typically emerge in infancy. Early indicators include weak muscle tone (hypotonia), difficulty feeding, impaired growth, lack of tear production, recurring lung infections, and trouble regulating body temperature. Older infants and young children with familial dysautonomia might hold their breath for extended periods, potentially leading to a bluish skin or lip discoloration (cyanosis) or fainting. This breath-holding behavior usually resolves by age six. Developmental milestones, like walking and speaking, are often delayed, although some affected individuals show no such delays.

School-aged children may experience additional signs and symptoms, including bedwetting, vomiting episodes, reduced sensitivity to temperature and pain, poor balance, scoliosis (abnormal spinal curvature), weak bones and a higher risk of fractures, and kidney and heart complications. Blood pressure regulation is also compromised, leading to potential drops in blood pressure upon standing (orthostatic hypotension), causing dizziness, blurred vision, or fainting. Conversely, periods of high blood pressure may occur during times of nervousness, excitement, or vomiting. Approximately one-third of children with familial dysautonomia have learning disabilities, such as a short attention span, requiring special education. As individuals reach adulthood, balance and unaided walking often become increasingly challenging. Other issues that can arise during adolescence or early adulthood include lung damage from repeated infections, impaired kidney function, and worsening vision due to optic nerve atrophy (shrinkage), which affects the transmission of visual information to the brain.

Inheritance:

Familial dysautonomia follows an autosomal recessive inheritance pattern. This means that an individual must inherit two copies of the mutated gene (one from each parent) to develop the condition. The parents, who each carry only one copy of the mutated gene, are usually asymptomatic carriers.