Kennedy’s Disease - Biology 33 Section 18659

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Kennedy's Disease (SBMA) Presentation Transcript:

SLIDE 1:
Hello everyone, my name is Dana Robin Sarmiento. In this presentation, I will be talking about Kennedy’s Disease also known as Spinal-Bulbar Muscular Atrophy.

SLIDE 2:
Kennedy’s Disease is a rare and degenerative disease of motor neurons. The affected motor neurons are the spinal and bulbar neurons, which originate in the central nervous system: in the spinal cord and brainstem, respectively. The spinal cord’s major functions are to provide sensory input to the brain and send motor impulses to spinal neurons. The bulbar region is composed of medulla, pons, and cerebellum - this region affects sensory and motor functions of bulbar muscles including swallowing and speech. In individuals with Kennedy’s Disease, the deterioration of the spinal and bulbar neurons eventually lead to atrophy in muscles that received impulses conducted by the neurons.

SLIDE 3:
Kennedy’s Disease is caused by a genetic flaw on the X-chromosome where the expansion of the DNA segment for the gene of a protein called androgen receptor is longer than normal. Normally, the androgen receptor facilitates cells to process androgens. In people with Kennedy’s Disease, the flawed androgen receptors residing in motor neurons interferes with the cell’s functions, causing the cell to degenerate and eventually die.

SLIDE 4:
Because Kennedy’s Disease is caused by an x-linked recessive gene, males are usually affected. This diagram represents an x-linked recessive inheritance with an unaffected father and a mother who carries the mutated gene. In this case, a daughter can either be unaffected or can become a carrier. On the other hand, a son can be unaffected or can inherit the mutated gene. According to a non-profit organization Kennedy’s Disease Association, about 1 in 40,000 people in the world are affected by Kennedy’s Disease.

SLIDE 5:
The diagnosis of this neuromuscular disease includes physical examination and family history. A blood test is also done as it can test for an enzyme called creatine kinase. This enzyme indicates muscle damage, which can also be found in other neuromuscular diseases - this may lead to a misdiagnosis. However, a genetic test with blood sample is considered to be the most accurate way to diagnose Kennedy’s Disease as it can detect the defect on the X chromosome.

SLIDE 6:
Signs and symptoms usually occur between the ages of 20 and 60, so diagnosis doesn’t occur until adulthood. These signs and symptoms occur in both affected men and women, however the women only have mild experiences.
Because bulbar neurons are affected, the function of the bulbar muscles are also affected. Weakened bulbar muscles cause problems in speech, swallowing, chewing, and breathing. These bulbar signs can lead to obstruction in the airway, dysphagia, and dyspnea. Weakened facial muscles decrease an individual’s ability to express certain emotions.
Because of neurological damage, muscles without functioning motor nerves to stimulate them become weak and start to waste and shrink, this is also known as muscular atrophy.

SLIDE 7:
In males with Kennedy’s Disease, gynecomastia occurs. This is when breast tissue is enlarged due to a hormonal imbalance. This imbalance comes from the interfered processing of androgens. Affected males also experience erectile dysfunction and loss of sperm count - these, in turn, reduce their chances of reproduction.

SLIDE 8:
Numbness and loss of sensation occurs in individuals with Kennedy’s Disease. Dysfunction of spinal neurons leads to abnormal responses to certain stimuli. For instance, in adults, the normal reaction to the stimulus on the bottom of a foot is a plantar reflex as shown here by the top foot. The abnormal reaction for adults, as shown by the middle and bottom foot, to this stimulus is the Babinski reflex, where the big toe extends upward and the toes fan outward.
When the affected individual intends to do something, tremors in their hands might occur and inhibit them to perform tasks. Large muscle spasms can occur, and certain postural changes can cause muscles to shake. In contrast to large muscles, fasciculation also occurs – it is when smaller muscles contract involuntarily.

SLIDE 9:
According to the Kennedy’s Disease Association, Kennedy’s Disease currently does not have cures or treatments for preventions but affected individuals do take medications for pain, muscle cramps and tremors. Another option is going to rehabilitation programs such as speech therapy, occupational therapy and physical therapy. In addition, exercise and a healthier diet can help alleviate and manage some of the symptoms, and even delay muscular atrophy.

SLIDE 10:
This concludes my presentation. Thank you for reading and listening.