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FTDNA_Chromo2 Table

The FTDNA_Chromo2 table stores the shared DNA segments reported by FTDNA’s chromosome browser. Each row is one segment shared between your kit and a match — the chromosome it falls on, its start and end positions, its length in centimorgans, and the number of SNPs it spans. A single match can produce several rows, one per shared segment.

Column Reference

ColumnTypeDescription
Idint (PK)Auto-incrementing primary key
eKit1stringYour kit (the kit whose chromosome browser was read)
eKit2stringThe match’s kit (the person you share the segment with)
chromosomeintChromosome number the segment falls on
cmfloatdecimalSegment length in centimorgans (cM)
p1intSegment start position — the base-pair coordinate where the shared segment begins on the chromosome
p2intSegment end position — the base-pair coordinate where the shared segment ends on the chromosome
snpsIintNumber of SNPs spanned by the segment
created_datestringDate the row was gathered (yyyy-MM-dd)
GF_SyncstringSync status flag
About p1 and p2: these are base-pair positions on the chromosome — p1 is where the shared segment starts and p2 is where it ends. The distance between them describes the physical span of the segment, while cmfloat gives its genetic length in centimorgans.

How It’s Populated

During an FTDNA gather, for each match that needs chromosome data the application calls FTDNA’s chromosome browser segment service for that match pair. FTDNA returns a list of shared segments, and the gatherer creates one FTDNA_Chromo2 row per segment: eKit1 is set to your kit, eKit2 to the match’s kit, and the chromosome, start position (p1), end position (p2), SNP count (snpsI), and centimorgan length (cmfloat) are filled in from the response. The created_date is stamped with the gather date.

Before inserting, the application checks for an existing row with the same eKit1, eKit2, chromosome, SNP count, and start position; if one is found, the segment is skipped, so re-gathering does not create duplicates.

Related Tables

  • FTDNA_Matches2 — the match list. Chromosome rows join back to matches on the eKit1/eKit2 pair.
  • FTDNA_ICW2 — In Common With (shared matches) for FTDNA kits.
  • FTDNA_Tree — family-tree individuals from matches’ linked trees.