| Step | Biological event | Evidence pointer (seed PMID) | Directness (human direct / model / in vitro / inferred) | What to verify in full text |
|---|---|---|---|---|
| 1 | Biallelic SYCE1 variant segregates with infertility phenotype | 25062452 | human direct | Confirm exact genotype(s), zygosity, pedigree segregation, affected/unaffected status, and whether all cases are conclusively biallelic |
| 2 | Variant causes SYCE1 loss or marked reduction of transcript/protein | 32402064 | model | Verify whether loss is due to nonsense-mediated decay, absent protein on western blot/IF, and whether any analogous human tissue data were shown |
| 3 | Damaging SYCE1 variants disrupt interaction with SYCP1 and/or C14ORF39/SIX6OS1 | 34718620 | in vitro | Confirm assay type, which variants were tested, effect size, and whether disruption differs by variant class |
| 4 | Disrupted SYCE1 function impairs synaptonemal-complex central element assembly | 34718620 | in vitro | Verify SC markers used, localization defects, and whether assembly failure was directly visualized or inferred |
| 5 | SC assembly failure leads to homologous chromosome synapsis failure during meiotic prophase I | 32402064 | model | Confirm cytological evidence for asynapsis, staging criteria, and whether any human meiotic-cell evidence exists |
| 6 | Unsynapsed chromosomes are associated with pachytene-stage meiotic arrest/checkpoint activation | 35718780 | human direct | Verify biopsy histology, immunofluorescence markers, checkpoint terminology, and whether arrest was complete or partial |
| 7 | Meiotic arrest results in germ-cell apoptosis/depletion | 32402064 | model | Confirm whether apoptosis or depletion was directly measured versus inferred from absent mature germ cells |
| 8 | Shared meiotic mechanism produces 46,XX primary ovarian insufficiency/primary amenorrhea and 46,XY non-obstructive azoospermia/spermatogenic arrest | 25062452; 35718780; 34718620 | inferred | Verify cross-sex phenotype breadth, number of unrelated families, endocrine/histologic detail, and whether sex-dimorphic outcomes are directly documented across cohorts |


*Table: This table organizes the seed-aligned mechanistic hypothesis from biallelic SYCE1 variation to meiotic failure and infertility phenotypes. It also highlights which links are direct versus inferred and what should be checked in the full texts.*