Huntington’s disease

Huntington disease (HD) is a rare neurodegenerative disorder of the central nervous system characterized by unwanted choreatic movements, behavioral and psychiatric disturbances and dementia. It is genetically transmitted as an autosomal dominant trait with complete penetrance and thus has an equal likelihood of affecting males and females.

About 30,000 Americans — one in every 10,000 — have Huntington’s. More than 200,000 individuals are known to be at risk because they have a parent with the disease.

The first description by Waters, of a patient with what we now call Huntington’s chorea, dates from 1842. But it was not until 1872, after the lecture and description of the disease by George Huntington, that it became known as Huntington’s chorea.

Huntington's disease is associated with both involuntary and voluntary movement disorder which progressively worsens over the course of the disease. Characteristic abnormal involuntary movements involve limb choreoathetosis, most conspicuous in the upper extremities and appearing as a random jerky movement or a slow and sinuous writhing.

Huntington’s also causes a decline in thinking and reasoning skills, including memory, concentration, judgment and ability to plan and organize.

HD symptoms do not usually start until adulthood – 30’s and 40’s is most common. Some people with the HD gene expansion develop mood or cognitive changes first, and then later develop chorea and movement symptoms.

HD is an autosomal dominant inherited disease caused by an elongated CAG repeat (36 repeats or more) on the short arm of chromosome 4p16.3 in the Huntingtine gene. This defect is “dominant,” meaning that anyone who inherits it from a parent with Huntington’s will eventually develop the disease.
Huntington’s disease

Notes:
CAG (cytosine (C), adenine (A), and guanine (G)), is a trinucleotide, the building stone of DNA.

Definition of renovascular hypertension

In most Westernized countries, and especially among older individuals, renovascular hypertension is the most remediable cause of elevated blood pressure.

Renovascular hypertension is a reversible cause of hypertension secondary to a decrease in renal perfusion pressure which activates the renin-angiotensin system and leads to the release of rennin and the production of angiotensin II.  It is a progressive disorder that can result in serious complications without adequate treatment.

Angiotensin II increases sodium reabsorption and induces postglomeruler and systemic arterial vasoconstriction, causing renovascular hypertension. The prevalence of renovascular hypertension was estimated at about 5% of all hypertensive individuals but it is varied form less than 1% to more than 50% depending on the degree of screening in the study population.

With prevalence of about 5%, renovascular disease represents the most frequent cause of secondary hypertension.

Unlike the diagnosis of most other cardiovascular and nephorologic conditions, renovascular hypertension can be diagnosed only retrospectively, by means of a physiologic blood pressure (BP) response to an intervention.
Definition of renovascular hypertension

Multiple sclerosis

Multiple sclerosis is an immune disorder affecting adults of all ages and the most common inflammatory disease of the central nervous system. It is unpredictable and can result either in only minor –physical impairment or in severe disability.

Multiple sclerosis is considered a demyelinating disease in that the myelin in the central nervous system is disseminated. Myelin, the insulator of nerves is attacked by the immune system because of improper recognition of self as intruder. The demyelinization may slow the nerve impulses, causing loss of muscle power or distortion of sensation, or may block them altogether.

Multiple sclerosis is caused by an interplay genetic and environmental factors. This incidence in the general population is about one in 800 but it is one in 50 for children of an affected parent, one in 20 for siblings of an affected person, and one in three for identical twins of multiple sclerosis patients.

Women are disproportionately affected outnumbering men nearly 2 to 1. The disease typically begins from age 20 to 50. However, individuals with disease onset after age 50 are not rare.

Early symptoms of multiple sclerosis may be mild and vague, and hence may be dismissed by affected individuals or their families. Such symptoms include blurred vision, tingling or numbness in the trunk or extremities, vertigo, intention tremor and clumsiness.
Multiple sclerosis