How many genes does a rat have? - briefly
The rat genome comprises roughly 25,000 protein‑coding genes. Including non‑coding sequences, the total gene count is estimated at about 30,000.
How many genes does a rat have? - in detail
The most recent reference assembly for the laboratory rat (Rattus norvegicus) lists roughly 23 000 protein‑coding genes. Ensembl release 110 (based on assembly GCF_015227845.2) records 23 040 protein‑coding loci, while RefSeq annotation adds a comparable number, yielding a consensus of 22 500–23 500 protein‑coding genes across major databases.
In addition to protein‑coding sequences, the annotation includes about 7 000 long non‑coding RNA genes, 1 200 microRNA genes, and several hundred small nucleolar RNAs. Summed together, the total gene count—protein‑coding and non‑coding—approaches 30 000 distinct transcriptional units.
Key points summarizing the current understanding:
- Protein‑coding genes: ~23 000 (Ensembl)
- Long non‑coding RNAs: ~7 000 (Ensembl)
- MicroRNAs: ~1 200 (miRBase, RefSeq)
- Other small RNAs (snoRNA, snRNA, etc.): several hundred
- Total annotated genes: ~30 000
These numbers result from high‑throughput whole‑genome sequencing combined with automated and manual annotation pipelines. Updates to the assembly and annotation are driven by improved transcriptome data (RNA‑Seq, Iso‑Seq) and comparative genomics with mouse and human genomes, which refine gene models and resolve previously ambiguous loci.
Strain‑specific variations can modestly affect gene counts. For example, the SHR (spontaneously hypertensive rat) and BN (Brown Norway) strains exhibit a few hundred strain‑specific gene predictions, primarily due to structural variations and copy‑number differences. Nevertheless, the core gene repertoire remains consistent across strains.
Comparatively, the rat shares roughly 85 % of its protein‑coding genes with mouse and 78 % with human, reflecting conserved mammalian functions while also retaining species‑specific adaptations.
The current consensus therefore places the rat genome at approximately 30 000 genes, with about 23 000 encoding proteins and the remainder comprising diverse non‑coding RNA families. Ongoing sequencing projects and annotation refinements are expected to adjust these figures modestly as new transcript evidence emerges.