Hb Seal Rock [(alpha 2)142 term-->Glu, codon 142 TAA-->GAA]: an extended alpha chain variant associated with anemia, microcytosis, and alpha-thalassemia-2 (-3.7 Kb).
Hb Seal Rock was first reported in a young African-American women and her 2-year-old daughter (1). It is an extended alpha chain variant which, like Hb Constant Spring, is present in small quantity and is expressed as an alpha-thalassemia. The mutation, TAA-->GAA affects codon 142 of the alpha 2 gene. In this family, the index case was a compound heterozygote for Hb Seal Rock trait and for alpha-thalassemia trait (-3.7 kb). Her hematologic expression was similar to mild Hb H disease, presumably because the Seal Rock mutation affects the alpha 2 gene that is normally responsible for approximately 70% of alpha-globin synthesis. Her daughter had only Hb Seal Rock trait, but was phenotypically alpha-thalassemia-2 trait due to the expression of the Seal Rock mutation on one of her alpha 2-globin genes, the other three alpha-globin genes being unaffected.
Merritt
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D
Department of Obstetrics and Gynecology, Washington University School of Medicine, St. Louis, MO 63110, USA.
Jones
R T
RT
Head
C
C
Thibodeau
S N
SN
Fairbanks
V F
VF
Steinberg
M H
MH
Coleman
M B
MB
Rodgers
G P
GP
D000328:Adult; D000595:Amino Acid Sequence; D000740:Anemia / Q000235:genetics*; D003062:Codon / Q000235:genetics; D005260:Female; D006455:Hemoglobins, Abnormal / Q000235:genetics*; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D017085:alpha-Thalassemia / Q000235:genetics*
D003062:Codon; D006455:Hemoglobins, Abnormal; C108107:hemoglobin Seal Rock