BC000 1 1 2 3 F 3 51 51 BC000 0 2 M 999 BC000 0 3 37 36 F 65 BC000 0 4 2 3 M 50 50 BC000 0 5 2 3 F 45 47 46 BC000 0 6 2 3 F 3 42 BC000 0 7 2 3 M 999 BC000 0 8 2 3 F 3 42 BC000 0 9 2 3 F 1 39 BC000 0 10 2 3 F 3 35 BC000 0 11 45 8 M 11 BC000 0 12 45 8 F 9 #### #!/usr/bin/perl use warnings; use strict; my $filename = 'pedigree_proband_testfile.txt'; open (FILE, "<", $filename) or die "Cannot open file $!"; my @data = ; my @column; my $motherID; foreach my $line (@data) { @column = split ( /\t/, $line); if ($column[13] eq "" && $column[4] ne "" ) { $motherID = join($column[2],$column[4]); if ("$motherID" eq "$column[2]") { print "$line\t\n"; } } }