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Carrier status

Not a medical test — for research and educational use only

Yeliztli analyses consumer genotyping-array data (23andMe / AncestryDNA), which is not a clinical-grade test. Results are not diagnostic, are not clinically validated, and must not be used to make medical decisions. Array data is especially unreliable for rare, disease-causing variants. Always confirm any finding with an accredited clinical laboratory and discuss it with a qualified clinician or genetic counsellor before acting on it. See the Intended use & disclaimers page for the details and the evidence behind this warning.

Carrier screening looks for a single copy of a disease-causing variant in genes where two copies (one from each parent) would be needed to cause a recessive condition. Being a carrier usually doesn't affect your own health, but it's relevant for reproductive planning.

What it looks at

A 7-gene reproductive panel:

  • CFTR (cystic fibrosis), HBB (sickle cell / beta-thalassemia), GBA (Gaucher), HEXA (Tay-Sachs), SMN1 (spinal muscular atrophy)
  • BRCA1 / BRCA2 — dual-role, also reported by the cancer module

What you'll see

Heterozygous (single-copy) Pathogenic/Likely-Pathogenic variants, grouped by inheritance pattern, each with ClinVar significance, review stars, an evidence rating, the associated condition, and reproductive context. A single recessive variant means you are typically an unaffected carrier, so these findings are framed around reproductive risk and partner testing.

For autosomal-recessive genes, the module also surfaces biallelic patterns as affected-status findings — worded as a disease-state result rather than a "typically unaffected" carrier, with copy-number caveats and a prompt to confirm with clinical-grade testing:

  • a homozygous (two-copy) P/LP variant; and

  • two distinct heterozygous P/LP variants in the same gene — a possible compound heterozygote, flagged as possible because genotyping arrays can't phase the variants (i.e. tell whether they sit on opposite chromosomes); it is affected-status only if they are in trans, which clinical testing would confirm.

  • HBB rs334 (sickle-cell trait) findings include personal health context (kidney, clot, and exertional considerations).

  • BRCA1/2 findings note their dual role and cross-link to the cancer module.

Good to know

  • GBA results are suppressed when derived from array data, because a nearby pseudogene (GBAP1) makes array genotyping of GBA unreliable.
  • SMN1 (spinal muscular atrophy) is not meaningfully screened from array data. SMA carrier status is a copy-number determination — the SMN1 exon-7 deletion behind the great majority of carriers — which a SNP array cannot measure; clinical screening uses dosage assays (qPCR/MLPA) that detect ~96% of carriers, and ACOG/ACMG recommend it pan-ethnically.1 This module checks only the rare intragenic SMN1 point mutations (~5% of pathogenic alleles), and only if they are on your chip — so a negative or absent SMN1 result here does not reduce your chance of being an SMA carrier. For reproductive planning, seek clinical SMN1 dosage carrier screening.
  • Carrier screening is not exhaustive — these are specific common variants, not full gene sequencing.

  1. The clinical utility of a risk-modifying SNP to detect carriers for spinal muscular atrophy with increased sensitivity (Ware et al., 2022, Mol. Genet. Genomic Med.) — routine SMN1 copy-number assessment detects ~96% of carriers; current guidelines recommend pan-ethnic SMA carrier screening. ↩