Two novel variants in CNNM2 disrupts magnesium efflux leading to neurodevelopmental disorders
Bibliographic record
Abstract
Background Hypomagnesemia, seizures, and impaired intellectual development 1 (HOMGSMR1) is a rare neurodevelopmental disorder associated with magnesium homeostasis disruption, caused by mutations in the CNNM2 gene. HOMGSMR1 demonstrates considerable clinical heterogeneity, but the genotype-phenotype relationship remains insufficient. Methods We recruited two unrelated families with NDDs, and potential variants were identified through whole exome sequencing and confirmed by Sanger sequencing. Quantitative PCR, Western blotting, immunofluorescent staining, and flow cytometry were used to assess functional changes in candidate CNNM2 variants. Results Two novel variants, p.E298del and p.P360R, in CNNM2 gene were identified. The unique facial features of proband 1 may broaden the known phenotypic spectrum of HOMGSMR1. Functional studies confirmed that the p.E298del and p.P360R variants increased CNNM2 transcription and protein levels, impairing the proper localization of the CNNM2 protein to the cell membrane. Two variant proteins accumulated in the cytoplasm and formed clumps. Furthermore, intracellular Mg2+ levels were higher in cells with these variants, disrupting magnesium homeostasis and potentially contributing to hypomagnesemia. Notably, the proteins of these two variants exhibited reduced stability and were prone to degradation, potentially providing new insights into the pathogenic mechanisms of CNNM2. Conclusion Our study expands the mutation and phenotypic spectrum, as well as the functional studies of CNNM2, and contributes to genetic testing and prenatal diagnosis in families with HOMGSMR1.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".