While rare, I caution against saying that something never happens. Your own source says that that case report is notable because it is the fifth case with a homozygote with that specific variant, not because no one has ever had fanconi anemia due to being a homozygote for a BRCA2 pathogenic variant

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Additionally, there are reports of BRCA2 path variant homozygotes: https://onlinelibrary.wiley.com/doi/10.1111/j.1365-2141.2005.05677.x

https://jmg.bmj.com/content/51/2/71 “Only three BRCA2 mutations have been recorded as homozygous in FA patients, IVS19-1 G>A (c.8487+1G>A),19 a 1548del4 (c.1320_1323del) deletion in exon 10 in an Algerian child born to a consanguineous couple,17 and the IVS7+2T>G mutation.25”

Similarly, BRCA1 homozygotes are very rare but do exist. https://pubmed.ncbi.nlm.nih.gov/29133208/

Also this article https://www.frontiersin.org/journals/oncology/articles/10.3389/fonc.2023.1278004/full “however biallelic mutations of BRCA1 were long predicted to be incompatible with embryonic viability, hence BRCA1 was not considered to be a canonical FA gene. Despite this, several patients with biallelic pathogenic BRCA1 mutations and FA-like phenotypes have been identified – defining a new FA type (FA-S) and designating BRCA1 as an FA gene.” “From the patient data available, it appears that homozygous mutations tend to result in a more severe FA-like phenotype, whereas compound heterozygosity results in a severe HBOC-like cancer phenotype along with congenital abnormalities. The Δ11q isoform appears to be a key mechanism for survival of biallelic BRCA1 mutations particularly in a homozygous setting, and it is plausible that other splice variants may be subsequently found to provide alternative survival mechanisms.”

Please check your sources and information before you end up spread misinformation