Discovery of a Missense Mutation (Q222K) of the APOE Gene from the Australian Imaging, Biomarker and Lifestyle Study

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

The loss in binding is thought to contribute to a decrease in the clearance of Aβ and thus is part of the mechanism for the increased risk of apoE ɛ4 allele carriers to develop AD.

“The loss in binding is thought to contribute to a decrease in the clearance of Aβ and thus is part of the mechanism for the increased risk of apoE ɛ4 allele carriers to develop AD [13–15].”

• cites [13] sourceNot checked — no full text of the source
• cites [14] sourceNot checked — no full text of the source
• cites [15] sourceDisputed

  The paper supports the background link between apoE4, impaired Aβ clearance, and increased AD risk. But its Discussion says direct apoE/Aβ binding is unlikely to explain clearance differences and proposes receptor- or transporter-mediated effects instead. That contradicts the claimed mechanism in which a loss of binding reduces clearance. (LLM, conf=0.88)

  Checked by a reasoning model — may be wrong.

  Experimental — accuracy not yet measured

Probably not a substantial claim: may not pass S3 (load-bearing).

The buildup and eventual deposition of Aβ is due to a 2-5% decrease in the clearance of Aβ from the brain.

“The buildup and eventual deposition of Aβ is due to a 2–5% decrease in the clearance of Aβ from the brain [9, 10].”

• cites [9] sourceDisputed

  The main-text passages under “Abstract” report about a 30% impairment in Aβ clearance in late-onset Alzheimer’s disease, not a 2–5% decrease. The limitations passage also says the association between impaired clearance and Alzheimer’s disease does not prove causality. No page numbers are provided in our copy. (LLM, conf=0.90)

  Checked by a reasoning model — may be wrong.

  Experimental — accuracy not yet measured
• cites [10] sourcePartly supported

  The ‘Estimated rates of amyloid-β accumulation’ section (page not supplied) links accumulation in sporadic Alzheimer’s disease to decreased clearance. But its 2–5% estimate describes an overall increase in deposition, not a measured 2–5% decrease in clearance. (LLM, conf=0.88)

  Experimental — accuracy not yet measured

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

APOE ɛ4 is the most jeopardizing allele, conferring a dose-dependent increase to the risk for AD and reducing the mean age of onset about ten years in homozygous ɛ4 persons compared to persons without ɛ4 allele.

“APOE ɛ4 is the most jeopardizing allele, conferring a dose-dependent increase to the risk for AD and reducing the mean age of onset about ten years in homozygous ɛ4 persons, compared to persons without ɛ4 allele [6, 7].”

• cites [6] sourceNot checked — no full text of the source
• cites [7] sourcePartly supported

  The Distribution of Age at Onset by APOE Genotype section (page not specified) reports a dose-dependent shift toward earlier onset as the number of ε4 alleles increases, and the paper calls ε4 an AD risk allele. It does not establish a dose-dependent increase in AD risk, identify ε4 as the highest-risk allele, or report that ε4 homozygotes have a mean onset about ten years earlier than people without ε4. (LLM, conf=0.86)

  Experimental — accuracy not yet measured

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

The Jacksonville (V236E) and R251G mutations are protective against sporadic AD.

“The discovery of the protective roles of Christchurch (R136S) in autosomal dominant PSEN1 familial AD and the Jacksonville (V236E), & R251G mutations that are protective against sporadic AD [17–20].”

• cites [18] sourcePartly supported

  The Results report that p.V236E was associated with markedly reduced risk of late-onset Alzheimer’s disease in the case-control series. The Results and Genotyping sections identify the variants studied, but our copy does not report a protective association for R251G. (LLM, conf=0.88)

  Experimental — accuracy not yet measured
• cites [19] sourcePartly supported

  The Introduction identifies APOE3-Jacksonville (V236E) as protective against AD dementia, and the Discussion says it confers protection against AD. Our copy does not address R251G; a search for that variant found no matching passage. Thus this source supports the Jacksonville part of the claim, but not the R251G part. (LLM, conf=0.88)

  Experimental — accuracy not yet measured
• cites [20] sourceSupported

Probably not a substantial claim: may not pass S3 (load-bearing).

The R145C mutant can result in altered function including mild triglyceride dyslipidemia.

“Other mutations like R145C mutant can results in altered function including mild triglyceride dyslipidemia [21].”

• cites [21] sourceSupported

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

The AIBL study is a longitudinal study of over 1,117 volunteers and includes amyloid PET imaging and repeated cognitive and behavioral tests.

“The Australian Imaging, Biomarker and Lifestyle (AIBL) study of aging is a longitudinal study of over 1,117 volunteers and includes amyloid positron emission tomography (PET) imagining, as well as several repeated cognitive and behavioral tests [24].”

• cites [24] sourceSupported

Classified as probably not a substantial claim. May combine two claims.

Rare APOE missense variants impact protein function and modify disease risk.

“This includes the important discoveries about rare APOE missense variants that impact protein function and modify disease risk.”

• cites [17] sourceSupported
• cites [18] sourcePartly supported

  The Discussion reports that the rare APOE missense variant p.V236E was associated with markedly decreased risk of late-onset Alzheimer’s disease. It describes effects on ApoE lipid binding, aggregation, and receptor binding as possibilities still under investigation, not demonstrated changes in protein function. The other rare variants studied were not shown to independently modify risk. (LLM, conf=0.88)

  Experimental — accuracy not yet measured
• cites [19] sourceSupported
• cites [20] sourcePartly supported

  The Abstract reports that the rare variants V236E and R251G are associated with substantially reduced Alzheimer disease risk. The Conclusions describe functional evidence suggesting that V236E reduces apoE oligomerization, but say that R251G’s protective mechanism remains unexplored. The paper therefore supports the risk claim, but not an established effect on protein function for both variants. (LLM, conf=0.88)

  Experimental — accuracy not yet measured

Probably not a substantial claim: may not pass S2 (checkable), S3 (load-bearing).

The combination of rare variants and sufficiently large studies to determine their disease impact have potential to develop new avenues of drug development that target APOE.

“The combination of rare variants and sufficiently large studies to determine their disease impact have potential to develop new avenues of drug development that target APOE [23].”

• cites [23] sourceSupported

Probably not a substantial claim: may not pass S3 (load-bearing).

As genome sequencing continues to expand, new potential disease modifying variants for AD are being discovered.

“As genome sequencing continues to expand new potential disease modifying variants for AD are being discovered [22].”

• cites [22] sourceSupported

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

ApoE ɛ2 and ɛ3 bind to Aβ; this binding is lost in the apoE ɛ4 variant.

“ApoE ɛ2 and ɛ3 bind to Aβ; however, this is lost in the apoE ɛ4 variant [11, 12].”

• cites [11] sourceNot checked — no full text of the source
• cites [12] sourcePartly supported

  The binding results (indexed under Materials and Methods; page unavailable) show that ApoE in cerebrospinal fluid binds Aβ peptide, but they do not establish binding separately for ε2 and ε3. A later passage says differences in binding among ApoE isoforms are a possibility; it does not show that binding is lost in ε4. (LLM, conf=0.88)

  Experimental — accuracy not yet measured

Probably not a substantial claim: may not pass S3 (load-bearing).

The Christchurch (R136S) mutation is protective in autosomal dominant PSEN1 familial AD.

“The discovery of the protective roles of Christchurch (R136S) in autosomal dominant PSEN1 familial AD and the Jacksonville (V236E), & R251G mutations that are protective against sporadic AD [17–20].”

• cites [17] sourcePartly supported

  The Abstract describes a PSEN1 E280A carrier with two copies of APOE3 Christchurch (R136S) whose clinical onset was delayed by nearly three decades. It calls the variant her most likely genetic modifier, but presents its protective effect as a hypothesis based on one homozygous carrier, not an established effect of the mutation in PSEN1 familial AD generally. (LLM, conf=0.86)

  Experimental — accuracy not yet measured

Probably not a substantial claim: may not pass S3 (load-bearing).

In mouse models, blocking the apoE:Aβ interaction can have significant effects on amyloid and tangle formation.

“And in mouse models blocking the apoE:Aβ interaction can have significant effects on amyloid and tangle formation [16].”

• cites [16] sourceSupported

May combine two claims.

Position 222 is at a flexible loop region of apoE, corresponding to the shoulder of a domain (residues 244-272) hypothesized to bind Aβ and involved in lipid binding.

“Structurally, position 222 is at a flexible loop region of apoE, corresponding to the shoulder of a domain (residues 244–272) hypothesized to bind Aβ [15] and involved in lipid binding [33].”

• cites [15] sourceCould not verify

  The cited paper’s Significance and Discussion sections address apoE–Aβ binding generally, but do not identify residues 244–272 as a hypothesized Aβ-binding domain. Searches for residues 244–272, position 222, and a C-terminal binding site found no passage addressing that structural claim. The separate lipid-binding statement is attached to citation [33], not this source. (LLM, conf=0.74)

  Experimental — accuracy not yet measured
• cites [33] sourceSupported

May combine two claims.

Whole exome sequencing of APOE from the donor confirmed a single nucleotide polymorphism in exon 4 translating to a rare Q222K missense mutation, validating the isoelectric point shift.

“Whole exome sequencing of APOE from the donor confirmed a single nucleotide polymorphism (SNP) in exon 4, translating to a rare Q222K missense mutation.”

• Also stated in: § RESULTS AND DISCUSSION · plain

  “The exon sequencing revealed a novel, non-synonymous, single nucleotide polymorphism (SNP) in exon 4 (Supplementary Fig. 1), translating to Q222K, and validating the shift in the protein isoelectric point.”

May combine two claims.

The anomalous sample, nominally ɛ4/ɛ4 by DNA genotyping, showed an apoE spot position with an unexpected basic shift, predicting a peptide with an additional positive charge to standard apoE ɛ4.

“That anomalous sample, nominally ɛ4/ɛ4 by DNA genotyping, showed an apoE spot position with an unexpected basic shift, predicting a peptide with an additional positive charge to that occupied by standard apoE ɛ4 (labelled μ in Fig. 1).”

May combine two claims.

The donor of the novel APOE variant was an Australian Caucasian male, 82 years of age at testing, with no cognitive impairment as measured by the Mini-Mental State Exam.

“The donor of the novel APOE variant was an Australian Caucasian male, 82 years of age at the time of testing, with no cognitive impairment, as measured by the Mini-Mental State Exam”

May combine two claims. The quote only partly states this claim.

The Q222K mutant protein's lack of detectable 45 kDa apoE-apoAII complex contrasted with ɛ3 carriers that display heteromeric and homomeric protein complexes.

“This contrasted with ɛ3 carriers that display heteromeric and homomeric protein complexes.”

Probably not a substantial claim: may not pass S3 (load-bearing).

The introduction of additional basic residues in apoE ɛ3 and apoE ɛ4 results in a shift in the isoelectric point of the proteins and was the basis of their nomenclature.

“The introductionof the additional basic residues in apoE ɛ3 and apoE ɛ4 results in a shift in the isoelectric point of the proteins and was the basis of their nomenclature [4, 5].”

• cites [4] sourceNot checked — no full text of the source
• cites [5] sourceNot checked — no full text of the source

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Each APOE allele encodes an apoE proteoform: apoE ɛ2 has two cysteine residues, apoE ɛ3 has C158R, and apoE ɛ4 has C112R/C158R.

“Each allele encodes for an apoE proteoform where two cysteine residues are present in apoE ɛ2, or mutated to arginine C158R in apoE ɛ3, or C112R/C158R in apoE ɛ4 [3].”

• cites [3] sourceNot checked — no full text of the source

Probably not a substantial claim: may not pass S3 (load-bearing).

There are three common APOE alleles in the general population: APOE ɛ2, APOE ɛ3, and APOE ɛ4.

“There are three common APOE alleles in the general population defined as: APOE ɛ2, APOE ɛ3, and APOE ɛ4 [2].”

• cites [2] sourceNot checked — no full text of the source

Probably not a substantial claim: may not pass S3 (load-bearing).

The mutation to arginine in apoE ɛ3 and ɛ4 produces one or two additional positive charges relative to apoE ɛ2 at biological pH.

“The mutation to arginine produces one or two additional positive charges relative to apoE ɛ2, at biological pH.”

• cites [4] sourceNot checked — no full text of the source
• cites [5] sourceNot checked — no full text of the source

Probably not a substantial claim: may not pass S3 (load-bearing).

The peptide amyloid-β (Aβ) is a major component of amyloid plaques.

“The peptide amyloid-β (Aβ) is a major component of amyloid plaques [8].”

• cites [8] sourceNot checked — no full text of the source

Probably not a substantial claim: may not pass S3 (load-bearing).

The AIBL study was approved by institutional human research ethics committees of Austin Health, St Vincent's Health, Hollywood Private Hospital and Edith Cowan University.

“The AIBL study was approved by the following institutional human research ethics committees of Austin Health, St Vincent’s Health, Hollywood Private Hospital and Edith Cowan University.”

Classified as probably not a substantial claim.

The apoE-apoAII complex occurs in ɛ2 and ɛ3 carriers but not ɛ4/ɛ4 homozygotes.

“this complex has been shown to occur in ɛ2 and ɛ3 carriers but not ɛ4/ ɛ4 homozygotes [35].”

• cites [35] sourceNot checked — no full text of the source

May combine two claims.

Reduction and alkylation of proteins prior to 2D gel analysis occurred under native conditions, whereas western sample preparation uses heat and the denaturing detergent sodium dodecyl sulfate.

“The reduction and alkylation of proteins prior to 2D gel analysis occurred under native conditions versus the sample preparation of the western that uses heat and the denaturing detergent sodium dodecyl sulfate.”

Probably not a substantial claim: may not pass S3 (load-bearing).

The apoE-apoAII complex in plasma was discovered in the late 1970s.

“The apoE-apoAII complex in plasma was discovered in the late 1970s [34]”

• cites [34] sourceNot checked — no full text of the source