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Clin Chim Acta. 2013 Sep 23;424:191-200. doi: 10.1016/j.cca.2013.06.007. Epub 2013 Jun 21.

HPLC-ESI-MS/MS analysis of hemoglobin peptides in tryptic digests of dried-blood spot extracts detects HbS, HbC, HbD, HbE, HbO-Arab, and HbG-Philadelphia mutations.

Author information

1
Biochemical Mass Spectrometry Laboratory, Centers for Disease Control and Prevention, 4770 Buford Hwy, NE, Mail Stop F-19, Atlanta, GA, 30341, United States. Electronic address: cph7@cdc.gov.

Abstract

BACKGROUND:

Hemoglobinopathies are mutations resulting in abnormal globin chain structure; some have clinically significant outcomes such as anemia or reduced lifespan. Five β-globin mutations are (c.20A>T, p.E6V), (c.19G>A, p. E6K), (c.79G>A, p.E26K), (c.364G>C, p.E121Q), and (c.364G>A, p.E121K), resulting in HbS (sickle-cell hemoglobin), HbC, HbE, HbD-Los Angeles, and HbO-Arab, respectively. One α-globin mutation is (c.[207C>G or 207C>A], p.N68K), resulting in HbG-Philadelphia.

METHODS:

HPLC-ESI-MS/MS analysis of dried-blood spot (DBS) punches from newborns extracted with a trypsin-containing solution provides greater than 90% coverage of α-, β-, and γ-globin amino acid sequences. Because the (c.20A>T, p.E6V), (c.19G>A, p. E6K), (c.79G>A, p.E26K), (c.364G>C, p.E121Q), (c.364G>A, p.E121K), and (c.[207C>G or 207C>A], p.N68K) mutations generate globin peptides with novel amino acid sequences, detecting one of these peptides in DBS extracts is indicative of the presence of a hemoglobinopathy in the newborn.

RESULTS:

The method described here can distinguish normal β-globin peptides from the mutant HbS, HbC, HbE, HbD-Los Angeles and HbO-Arab peptides, as well as normal α-globin peptide from the mutant HbG-Philadelphia peptide, allowing the identification of unaffected heterozygotes such as HbAS, and of compound heterozygotes such as HbASG-Philadelphia.

CONCLUSIONS:

This HPLC-ESI-MS/MS analytical approach provides information that is not available from traditional hemoglobin analyses such as isoelectric focusing and HPLC-UV. It is also capable of determining the amino acid sequence of hemoglobin peptides, potentially allowing the detection of numerous hemoglobinopathies resulting from point mutations.

KEYWORDS:

CID; DBS; Dried-blood spot; ESI; HPLC–ESI-MS/MS; Hb; Hemoglobinopathies; IEF; MALDI; SIM; collision-induced dissociation; dried-blood spot; electrospray ionization; hemoglobin; isoelectric focusing gel; matrix-assisted laser desorption ionization; single-ion monitoring

PMID:
23796846
DOI:
10.1016/j.cca.2013.06.007
[Indexed for MEDLINE]

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