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Variant Hemoglobins
Newborn Screening and Hemoglobin E
A newborn screening result of Hgb EF or Hgb FE will be presumed to be
Hgb E-beta thalassemia, and requires repeat electrophoresis and family
studies to confirm or deny diagnosis.
Hemoglobin E is the most common abnormal hemoglobin identified in the
state of California on newborn screening. It is common in Laos, Cambodia
and Thailand. Hemoglobin E results from a mutation in an exon
(exon 1, codon 26: GAG to AAG) that creates an alternate splice site competing
with the normal splice site. This results in abnormal hemoglobin production
and mild thalassemia in the homozygous
state. In the homozygous state it produces a mild microcytic anemia with
a hemoglobin usually above 10 gm/dl. Electrophoresis reveals appoximately
90% Hgb E with varying amounts of Hgb F. The heterozygote has a hemoglobin
of about 12 gm/dl with microcytosis and an electrophoretic pattern consistent
with Hgb E plus Hgb A2 of 20 to 30%. When Hgb E trait combines
with other more severe beta thalassemias, Hgb E-beta thalassemia can produce
an anemia that is profound requiring chronic transfusion therapy. All
children who have Hgb E and Hgb F on their state screen require scrutiny
for emergence of a severe thalassemia syndrome. Individuals who have Hgb
EE do not have significant anemia and do not require special care except
that they should not be treated with iron for anemia.
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