CHARACTERIZATION OF A NEW HLA-B ALLELE, B*3913, IN A BRAZILIAN CAUCASIAN.
I. De Canck1, M.E. Moraes2, R. Maertens1,
N. Vande Casteele1, G. Van Reybroeck1, B. Vanderborg1,
J.R. Moraes2,3 and R. Rossau1. 1Innogenetics
N.V., Gent, Belgium; 2Lab de Imunogenética, HSE/INCA,
Rio de Janeiro, Brazil and 3Lab de Imunogenética, Dept.
Histo/Embriol., I. Biologia, UERJ, Rio de Janeiro, Brazil.
In order to evaluate the prototype Line Probe Assay (LiPA)
HLA-B strips, a panel of 20 samples which had been previously typed by
serology, was typed using the LiPA. The LiPA, based on the reverse hybridization
principle, consists of a specific amplification of exons 2 and 3 of the
HLA-B alleles and subsequent hybridization with 60 probes immobilized on
a membrane-based strip. The LiPA HLA-B has been designed to allow typing
at the allele group level. No discrepancies between the LiPA and serology
occurred. One cell, however, from a Brazilian of Caucasian origin, serologically
typed as B39/B52, showed an aberrant HLA-B probe pattern on strip, and
was typed as B*52012/B*39new. The presumed novel B39 allele had the same
probe pattern as B*3908, but reacted negatively with the probe specific
for CTG at codon 180. To check whether this probe reacted accurately or
whether a new allele was involved, the B*39new allele was separated from
the B*52012 allele by allele-specific amplification, and subsequently sequenced
using the Dye Deoxy Terminator Cycle Sequencing kit (Applied Biosystems)
and an automated DNA sequencer model 373A (Applied Biosystems). Sequence
analysis of exons 2 and 3 revealed a T (B*3908)-to-G nucleotide substitution
at position 539 (codon 180), confirming the probe reactivity on strip,
and resulting in an Arg (B*3908)-to-Leu substitution. Furthermore, the
sequence revealed a silent mutation at position 246: a G (B*3908)-to-A
nucleotide switch. The sequence has been sent to the EMBL databank and
the HLA nomenclature commission, and was named B*3913.