This report describes Alzheimer disease 4 (AD4), which is a subtype of Alzheimer disease; AD3 exhibits an autosomal dominant pattern of inheritance. The human gene implicated in this disease is PSEN2 (Presenilin 2), the catalytic component of a gamma-secretase complex. Gamma-secretase is responsible for proteolytic cleavage of amyloid precursor protein (APP) and NOTCH receptor proteins. PSEN2 is also implicated in dilated cardiomyopathy 1V (CMD1V, FBhh0000155). There is a single fly ortholog of PSEN2, Dmel\Psn, for which classical hypomorphic alleles, RNAi-targeting constructs, and alleles caused by insertional mutagenesis have been generated. Dmel\Psn is also orthologous to the human gene PSEN1 (see report for AD3, FBhh0000120).
Multiple different UAS constructs of the human gene Hsap\PSEN2 have been introduced into flies, including wild-type PSEN2 and genes carrying mutational lesions implicated in AD4. Variant(s) implicated in human disease (as transgenic human gene, PSEN2): M239V and N141I variant forms of the human gene have been introduced into flies, but have not been characterized to date.
For data concerning disease models using the fly Psn gene, see the report for 'Alzheimer disease, presenilin-related' (FBhh0000623).
[updated Aug. 2019 by FlyBase; FBrf0222196]
Alzheimer disease (AD) is the most common form of progressive dementia in the elderly. [from MIM:104300; 2016.01.08]
Memory loss is the most common sign of Alzheimer disease. As the disorder progresses, some people with AD experience personality and behavioral changes; other common symptoms include agitation, restlessness, withdrawal, and loss of language skills. Total care is usually required during the advanced stages of the disease. Affected individuals usually survive 8 to 10 years after the appearance of symptoms, but the course of the disease can range from 1 to 25 years. Death usually results from pneumonia, malnutrition, or general body wasting. [from Genetics Home Reference, Alzheimer disease; 2016.01.08]
Alzheimer disease can be classified as early-onset or late-onset. The signs and symptoms of the early-onset form appear before age 65, while the late-onset form appears after age 65. The early-onset form is much less common than the late-onset form, accounting for less than 5 percent of all cases of Alzheimer disease. [from Genetics Home Reference, Alzheimer disease; 2016.01.08]
[ALZHEIMER DISEASE 4; AD4](https://omim.org/entry/606889)
[PRESENILIN 2; PSEN2](https://omim.org/entry/600759)
Alzheimer disease 4 (AD4) is characterized by typical symptoms of Alzheimer disease (described above).
Alzheimer disease 4 is inherited as an autosomal dominant; it is associated with heterozygous mutations in the PSEN2 gene. [from MIM:606889; 2016.01.08]
The PSEN2 gene encodes presenilin-2, which forms the catalytic component of a gamma-secretase complex. Gamma-secretase is responsible for proteolytic cleavage of amyloid precursor protein (APP) and NOTCH receptor proteins. Gamma-secretase is a multiprotein complex containing PSEN1 or PSEN2 and multiple other components. [from MIM:104311, MIM:600759; 2016.01.08]
Many to one: 2 human to 1 Drosophila. Two human genes, PSEN1 and PSEN2, are orthologous to the fly gene Dmel\Psn.
Ortholog of human genes PSEN2 and PSEN1 (1 Drosophila to 2 human). Dmel\Psn shares 47-48% identity and 59-62% similarity with the 2 human genes.
