use strict;
use warnings;

my $inputFile = <>;

open my $inputFH, q{<}, $inputFile
   or die qq{open: < $inputFile: $!\n};
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This produces

$ cat spw718152.dat
SNPSTER2_50_3_1_119_588        10
SNPSTER2_50_3_1_121_522        16
SNPSTER2_50_3_1_119_260        27
$ ./spw718152
spw718152.dat
Unsuccessful open on filename containing newline at ./spw718152 line 8
+, <> line 1.
open: < spw718152.dat
: No such file or directory
$
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Adding the chomp will allow the file to open. Using map and taking advantage of the default behaviour of split, which is to operate on $_ splitting on whitespace (including newlines) and discarding empty trailing fields, gives us this.

use strict;
use warnings;

use Data::Dumper;

chomp( my $inputFile = <> );

open my $inputFH, q{<}, $inputFile
   or die qq{open: < $inputFile: $!\n};

my %dataItems =
   map { split }
   <$inputFH>;

close $inputFH
   or die qq{close: < $inputFile: $!\n};

print Data::Dumper->Dumpxs( [ \ %dataItems ], [ q{*dataItems} ] );
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Which produces.

$ ./spw718152
spw718152.dat
%dataItems = (
               'SNPSTER2_50_3_1_121_522' => '16',
               'SNPSTER2_50_3_1_119_588' => '10',
               'SNPSTER2_50_3_1_119_260' => '27'
             );
$
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I hope this is of interest.

Cheers,

JohnGG