| ffN {HLAtools} | R Documentation |
Identify and Annotate Gene Features in Pseudogenes and Gene Fragments.
Description
HLA pseudogenes and gene fragments many not share all of the gene features of their expressed homologs. The ffN() function generates a list object identifying the features present in a given gene fragment or pseudogene with a genomic alignment file. This includes annotations of the differences between the pseudogenes and gene fragments, and their expressed homologs. Pseudogenes and gene fragments are identified in the IMGTHLAGeneTypes data object.
Standard Features
E - Exon, a peptide-encoding sequence
I - Intron, an intervening sequence found between Exons
U - UTR, an untranslated region of sequence preceding the first Exon or following the last Exon
Additional Features used in these annotations, based on boundaries indicated in the sequence alignment, are:
H - Hybrid, a sequence that includes at least one known feature sequence and one nucleotide sequence that does not correspond to a known feature
J - Join, a sequence that includes two or more features that are separated by a feature boundary in the reference
N - Novel, a novel sequence that does correspond to a known feature sequence
S - Segment, a subset of a longer feature sequence Reference Genes
HLA-C genomic sequence is used as the reference for class I pseudogenes and gene fragments.
HLA-DPA1 and -DPB1 genomic sequences are used as the references for class II pseudogenes -DPA2 and -DPB2, respectively.
Usage
ffN(version)
Arguments
version |
A character string identifying the pertinent IPD-IMGT/HLA Database release version (e.g., "3.55.0") under which the returned object is generated. This parameter does not impact the generation of the feature names or annotations, and is only included to provide IPD-IMGT/HLA Database release version context. |
Value
A list object where each element is the name of a pseudogene or gene fragment. Each of these elements is a list of 'features' and 'annotation'. "Features" identifies the gene features for that gene, ordered from 5' to 3'. Because these genes are not-expressed, the three standard gene features (U, Untranslated Region (UTR); E, Exon; and I, Intron) may not always be present. In these cases, H, J, N and S features (defined below) are returned. Each feature identifier is followed by an identifying number (e.g. U.5 is the 5' UTR, and E.3 is Exon 3). "Annotation" provides the composition of the non-standard H, J, N and S features for each gene. #'
Note
Features and their annotations have been identified manually. Feature annotations will not change unless a new pseudogene or gene fragment is added in a future release, in which case new annotations will be generated.
The H and J features are described for class I pseudogenes and gene fragment sequences, all of which are described relative to the HLA-C reference sequence. Feature length differences for DPA2 and DPB2, relative to the DPA1 and DPB1 references, are noted in annotations of standard feature abbreviations (E, I and U).
No annotations are included for the DRB2, DRB6, DRB7, and DRB9 genes, as genomic alignments for these genes are not available.
For internal HLAtools use.
Examples
fragmentFeatureNames <- ffN("3.35.0")