Scientists are two different types of Alzheimer’s disease

Scientists have come to the realization that genes play an important
role in Alzheimer’s disease. Most genetic diseases are caused by either
a genetic mutation or a permanent change in one or more specific genes (“Alzheimer’s Disease Genetics
Fact Sheet,” n.d.) Genes control the function of every cell in your body.
Some genes control basic characteristics whereas other genes control the likelihood
of developing certain diseases such as Alzheimer’s disease. There are two different
types of Alzheimer’s disease and both have a genetic component. The two
types include early-onset and late-onset. Early on-set can be caused by an inherited
change in one of three genes or a different genetic component that is not
related to these three genes. The cause for late-onset is still not completely
understood but scientists believe it is a combination of environmental,
genetic, and lifestyle factors that affect the person’s risk. Although the
causes of the two types have been studied to be different, they are similar in
the symptoms that are often seen in an individual that is affected by the

            Early-onset Alzheimer’s disease is
known to be caused by a mutation on one of three
chromosomes. The chromosomes are 21, 14, and 1 and all the mutations cause abnormal
proteins to be formed. These proteins include: amyloid precursor protein (APP),
presenilin-1 (PS1), and presenilin-2 (PS2). The mutation that is seen the most
is in the PS1 gene. (Strobel, n.d.) APP and PS2 mutations are much rarer but
can still cause early-onset Alzheimer’s. If a pathogenic mutation is seen in
one of these three genes, then it is almost guaranteed the person will develop
the disease. Although early-onset is much rarer than late-onset they are
outwardly the same. “Some studies have noted that the pathologic hallmarks are
more severe in eFAD than LOAD, and may be concentrated in different regions. These
differences in underlying mechanism suggest that treatments for eFAD may
overlap with, but not always be identical to, treatments being developed for
LOAD.” (Strobel,

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            Late-onset Alzheimer’s disease is unknown what the definitive
cause is but one genetic risk factor that researchers have determined is having
one form of apolipoprotein (APOE) gene on chromosome 19. APOE comes in several
types of forms but APOE four increases the risk for Alzheimer’s disease. An individual can
have zero to two APOE four alleles, but the more alleles you have increases the
risk of developing the disease. (“Alzheimer’s Disease Genetics Fact Sheet,” n.d.) Some people will
inherit an APOE allele and never develop the disease and others who do not
inherit the allele will develop Alzheimer’s disease. Therefore, the cause of
late-onset Alzheimer’s disease is still not definitive. A blood test can be used
to identify if a person has the APOE risk factor allele, but it will not tell
you if you will develop Alzheimer’s disease. As research progresses,
researchers are uncovering links between late-onset Alzheimer’s and numerous other genes
although the exact role of these genes are not clear now. These genes are also
similar in that they are not guaranteed to cause Alzheimer’s if you have the gene and
vice versus.

            Therefore, although several genetics researchers have identified possible
new insights involving Alzheimer’s disease that may lead to effective
interventions, many causes are still uncertain. Until Alzheimer’s disease can be studied
further, possible cures and definitive causes will continue to stay unknown.
Overall, genetics has seen to have a large impact on the chances a person should
develop Alzheimer’s disease.