HEMOGLOBIN

Vol. 28, No. 2, pp. 151–156, 2004

SHORT COMMUNICATION

Thalassemia Intermedia Due to Co-inheritance ofbb0/bb+-Thalassemia and (– –SEA) aaaaaa-Thalassemia/Hb

Westmead [aaaaa122(H5)His > Gln (aaaaa2)] in a Chinese Family

Wai-Shan Wong,1 Amy Y-Y. Chan,1 Sze-Fai Yip,2

and Edmond Shiu-Kwan Ma1,*

1Division of Hematology, Department of Pathology, The University of

Hong Kong, Queen Mary Hospital, Hong Kong,

P.R. China2Department of Medicine, Tuen Mun Hospital, Hong Kong,

P.R. China

ABSTRACT

Two brothers from a Chinese family with b-thalassemia intermedia who harbor both

a- and b-globin gene defects are described. They are both compound heterozygous for

codons 41/42 (-CTTT) b0-thalassemia and nt - 28 (A > G) b+-thalassemia mutations

together with concurrent (– – SEA) a-thalassemia (SEA) deletion. One sibling also

harbors Hb Westmead, giving an unusual genotype of b0/b+-thalassemia and (– – SEA)

a-thalassemia/Hb Westmead. With respect to the age at presentation and transfusion

requirement, this subject shows a milder clinical phenotype than his brother, most

probably explainable by the presence of Hb Westmead in addition to the SEA

deletion, which causes a further amelioration of the a-chain excess and hence a less

severe disease. For areas with high prevalence of both a- and b-thalassemia mutations,

their interactions should always be considered in genotype phenotype correlation.

Moreover, routine laboratory diagnostic strategy for non-deletional a-globin gene

*Correspondence: Dr. Edmond Shiu-Kwan Ma, Division of Hematology, Department of

Pathology, The University of Hong Kong, Queen Mary Hospital, 102 Pokfulam Road, Hong

Kong, P.R. China; Fax: +852-2817-7565; E-mail: eskma@hkucc.hku.hk.

151

DOI: 10.1081/HEM-120035917 0363-0269 (Print); 1532-432X (Online)

Copyright D 2004 by Marcel Dekker, Inc. www.dekker.com

Hem

oglo

bin

Dow

nloa

ded

from

info

rmah

ealth

care

.com

by

Yor

k U

nive

rsity

Lib

rari

es o

n 11

/04/

14Fo

r pe

rson

al u

se o

nly.

ORDER REPRINTS

mutations in the Chinese may need to include Hb Westmead, as it is a common a-globin

gene mutation in our population apart from Hb Constant Spring and Hb Quong Sze.

Key Words: Thalassemia intermedia; a- and b-thalassemia interaction; Hb

Westmead; Genotype phenotype correlation.

Thalassemia is a family of genetic disorders characterized by reduced synthesis of

one or more of the globin chain subunits of the hemoglobin (Hb) molecule. Imbalance

of globin chain production that results in ineffective erythropoiesis and chronic anemia

is the major factor in the pathophysiology of the thalassemic disorders. For

geographical areas where both a- and b-thalassemia (thal) mutations are prevalent,

such as South East Asia and Southern China including Hong Kong (1), a spectrum of

clinical manifestations may result from the interaction of mutations affecting the a- and

b-globin gene loci. We describe two siblings from a Chinese family with an unusual

combination of a- and b-globin gene defects in the form of co-inheritance of b0/b+-thal

and (– –SEA) a-thal/Hb Westmead [a122(H5)His > Gln (a2)] (Table 1). The phenotypic

modification of b-thal by a concurrent a-globin chain mutation is discussed.

The proband was a 39-year-old man who presented first at the age of 8 for anemic

symptoms and recurrent chest infection. His Hb level at diagnosis was as low as 4.0 g/

dL. Physical examination showed pallor, jaundice and hepatosplenomegaly. Peripheral

blood film examination showed markedly hypochromic microcytic red cells, with many

circulating nucleated red cells. High performance liquid chromatography (HPLC)

showed the presence of Hb A, high Hb A2 (8.8%) and increased Hb F (66.0%),

consistent with b-thal intermedia. The percentages of different Hb components might

be slightly affected by blood transfusions. Cellulose and citrate gel electrophoresis

showed the presence of Hb A and increased Hb F without additional abnormal bands.

Table 1. Hematological and genotypic findings for the two siblings in this report.

Parameters Proband Brother

Sex-age M-39 M-32

Age at onset (years) 8 10

Hb (g/dL) level at diagnosis 4.0 8.0

Steady state Hb (g/dL) 7.0–7.5 7.8–8.7

MCV (fL) 63.8 58.5

MCH (pg) 19.4 18.4

Hb A2 (%) 8.8 8.0

Hb F (%) 66.0 70.2

Hb H bodies Negative Negative

a Genotype – – SEA/aa – – SEA/aWestmeadab Genotype b41/42/b– 28 b41/42/b�28

Transfusion history Every 3 months None since age 15

Ferritin (pmol/L) 1492.0 2061.0

Normal ranges for males: Hb 13.0–18.0 g/dL; MCV 80.0–96.0 fL; MCH 27.0–32.0 pg; Hb

F < 0.9%; Hb A2 2.3–3.0%, ferritin 115.0–884.0 pmol/L.

152 Wong et al.

Hem

oglo

bin

Dow

nloa

ded

from

info

rmah

ealth

care

.com

by

Yor

k U

nive

rsity

Lib

rari

es o

n 11

/04/

14Fo

r pe

rson

al u

se o

nly.

ORDER REPRINTS

Hb H inclusion bodies were not detected. Genotypic studies revealed that he was a

compound heterozygote for the �28 (A > G) (b+) and codons 41/42 (-CTTT) (b0)

mutations with a co-inherited a-thal deletion (– –SEA). He required regular monthly

blood transfusions to maintain his pre-transfusion Hb level at around 8.0 g/dL. At the

age of 11, splenectomy was performed. Since then, the frequency of blood transfusions

was reduced to once every 3 months. As he became a teenager, he developed

complications related to iron overload which resulted in growth retardation,

hypogonadotrophic hypogonadism, asymptomatic cardiac dysfunction and deranged

liver function. He was put on iron chelation therapy, and the latest ferritin level at last

follow-up was 2073 pmol/L.

His younger brother, who is now 32 years of age, presented as the age of 10 with

symptomatic anemia and was diagnosed as b-thal intermedia. He required regular blood

transfusions (2 to 4 times per year), which was less frequently than his brother. His

steady state Hb level was maintained at 8.0–9.0 g/dL. Subsequently, he was lost to

follow-up from the age of 15 as he became asymptomatic. He was admitted to hospital

with a chest infection a few years ago; on physical examination he was noted to have

mild Cooley’s facies, pallor, jaundice and hepatosplenmegaly. Hematological inves-

tigations showed: Hb 8.9 g/dL, MCV 54.6 fL, and MCH 17.6 pg. Results of Hb pattern

analysis were similar to his brother, showing the presence of Hb A, high Hb A2 (8.0%)

and markedly increased Hb F (70.2%). Hemoglobin electrophoresis did not reveal any

abnormal variants or bands that corresponded to Hb H/Hb Bart’s. Again, no Hb H

inclusion bodies were detected. Genotyping studies showed identical b-thal mutations

as his brother, with concurrent compound heterozygosity for the SEA deletion and Hb

Westmead [codon 122 (CAC > CAG) (a2) mutation], i.e., – –SEA/aWestmeada configu-

ration. He achieved normal growth and sexual function. Fasting sugar and testosterone

levels were normal. An echocardiogram showed mitral regurgitation and tricuspid

regurgitation, while the left ventricular ejection fraction was normal. This notwith-

standing, his ferritin level was elevated at 3774 pmol/L, and iron chelation therapy

commenced at age 30.

It has been shown that co-inheritance of a-thal may ameliorate the clinical

phenotype of severe b-thal (2). As the pathogenesis of b-thal involves excessive

intracellular precipitation of a chains causing damage to the erythroid precursors and

intramedullary cell death, co-inheritance of a-thal reduces globin chain imbalance by

decreasing a-globin chain synthesis, and therefore, leads to a milder disease. The

proband’s younger brother also carries an additional a-globin gene mutation, Hb

Westmead. Clinically, he presented later in life and had a higher Hb level at

presentation. He also required less frequent transfusions with a transfusion-free period

of 10 years. He has not yet developed complications of iron overload despite an

elevated ferritin level. However, complications of iron overload will inevitably occur

later in life, even without transfusions, as a result of increased iron absorption due to

chronic anemia. Therefore, regular follow-up and monitoring of his Hb level together

with ferritin level and iron saturation, is still mandatory in such cases. Iron chelation

should be started promptly before complications of iron overload arise. The presence of

the XmnI Gg polymorphism and globin chain synthesis ratio, however, were not

determined in these two cases.

Diagnosis of concurrent a- and b-thal cannot rely on Hb pattern study alone, as

illustrated by the above two cases. We have also previously shown that Hb H inclusion

Thalassemia Intermedia in Chinese Family 153

Hem

oglo

bin

Dow

nloa

ded

from

info

rmah

ealth

care

.com

by

Yor

k U

nive

rsity

Lib

rari

es o

n 11

/04/

14Fo

r pe

rson

al u

se o

nly.

ORDER REPRINTS

bodies are only occasionally present, or are not detectable at all in the setting of an Hb

H genotype in association with heterozygous b-thal (3). Therefore, molecular study

remains the gold standard of diagnosis of a- and b-thal interaction, which is expected

to occur in areas such as Hong Kong (1), with a high prevalence of both abnormalities.

A family study is also useful in these cases, both for phenotypic diagnosis and proper

genetic counseling.

Hb Westmead, first described by Fleming et al. (4) in 1980 in a family who

emigrated from Guangdong in Southern China to Australia, is one of the most common

Hb variants in Guangxi Province (5,6). Seven out of 738 patients attending an

Outpatient Clinic in a Center located in Guangxi, were found (by molecular analyses)

to carry the Hb Westmead variant (5). The prevalence of this variant in Hong Kong is

not known. It results from a mutation in codon 122 (CAC > CAG) of the a2-globin

gene leading to a His > Gln replacement. Hb Westmead is a slightly unstable variant,

and does not separate from Hb A by electrophoresis or isoelectric focusing (IEF) (5,7).

Diagnosis is dependent on identification of the aWestmead mutation by dot-blot hybrid-

ization using 32P-labeled synthetic oligonucleotide probes (7). The mutation creates an

StuI restriction cleavage site, and is also amenable to detection by polymerase chain

reaction (PCR) using the restriction enzyme StuI (5). We happened to identify Hb

Westmead in these two siblings and a previously reported family (8), based on nega-

tive hybridization of normal and mutant probes on dot-blot analysis for Hb Quong

Sze [a125((H8)Leu > Pro (a2); codon 125 (CTG > CCG)], which lies in close proximity

to codon 122. The presence of Hb Westmead was subsequently confirmed by direct

nucleotide sequencing of the a2-globin gene (Fig. 1). It follows, therefore, that

Hb Westmead should be considered in face of anomalous dot-blot hybridization

signal for the detection of Hb Quong Sze. More importantly, as Hb Westmead is

a common a mutant in the Chinese, apart from Hb Constant Spring [a142, Term > Gln

(a2) (TAA > CAA)] and Hb Quong Sze (G.F. Lung, Nanning, Guangxi, personal

Figure 1. Direct nucleotide sequencing of the a2-globin gene, showing the CAC > CAG mutation

at codon 122, consistent with Hb Westmead. The normal allele is absent since the patient carries the

SEA deletion on the other chromosome.

154 Wong et al.

Hem

oglo

bin

Dow

nloa

ded

from

info

rmah

ealth

care

.com

by

Yor

k U

nive

rsity

Lib

rari

es o

n 11

/04/

14Fo

r pe

rson

al u

se o

nly.

ORDER REPRINTS

communication), it should be screened for in routine laboratory diagnostic strategies

for a-globin gene mutations.

There are only a few reports on the co-inheritance of the Hb H genotype and

compound heterozygozity for b-thal from Greek and Sardinian families, respectively

(9–11). In the Sardinian family, the proband, who was diagnosed as homozygous for

b0-thal and a compound heterozygote for a-thal-1 and a-thal-2, based on hematological

findings, Hb pattern analysis and globin chain synthesis ratio, behaves clinically as

b-thal major (10). On the other hand, a Greek patient, who was characterized at the

molecular level, with a three a-globin gene deletion due to (– –MED/�a� 3.7) in

association with a compound heterozygous b0/b+-thal [IVS-I-6 (T > C) and IVS-I-1

(G > A)], shows a thalassemia intermedia phenotype, although the MCH value is

markedly low at 13.9 pg, signifying that the red cells are poorly hemoglobinized (11). The

interaction of various a and b genotypes is therefore complex, and depends, to a

large extent, on whether there is residual normal a- and b-globin chain synthesis, and

the degree of imbalance. Instead of having deletional a-globin gene mutations, the

brother of our proband shows compound heterozygosity for deletional and nondele-

tional a-globin gene mutations. In terms of age at presentation and transfusion

requirements, he shows a milder clinical phenotype than the proband. This is most

probably explained by the presence of Hb Westmead in addition to the SEA deletion,

which causes a further amelioration of the a chain excess, and hence, a less severe

disease. Interestingly, similar to other cases with two b-thal alleles associated with an

Hb H genotype (9–11), the two brothers in this report showed high Hb A2 levels of 8.8

and 8.0%, respectively. While the exact cause remains to be defined, it is plausible that

the high Hb A2 levels in these cases reflect the survival advantage of red cells with

enhanced d chain production, which further reduces a chain excess and improves

overall globin chain balance.

REFERENCES

1. Lau YL, Chan LC, Chan AYY, Ha SY, Yeung CY, Waye JS, Chui DHK.

Prevalence and genotypes of a- and b-thalassemia carriers in Hong Kong—

implications for population screening. N Engl J Med 1997; 336(18):1298–1301.2. Olivieri NF. The b-thalassemias. N Eng J Med 1999; 341(2):99–109.3. Ma ESK, Chan AYY, Au WY, Yeung YM, Chan LC. Diagnosis of concurrent Hb H

disease and heterozygous b-thalassaemia. Haematologica 2001; 86(4):432–433.4. Fleming PS, Hughes WG, Farmile RK, Wyatt K, Coopers WN. Hemoglobin

Westmead (a2 122 (H5) His!Gln b2: a new hemoglobin variant with the

substitution in the a1b1 contact area. Hemoglobin 1980; 4(1):39–52.5. Jiang NH, Liang S, Wen XJ, Liang R, Su C, Tang Z. Hb Westmead: an a2-globin

gene mutation detected by polymerase chain reaction and Stu I cleavage.

Hemoglobin 1991; 15(4):291–295.6. Liang S, Tang Z, Su C, Lung Q, Liang R, Fei YJ, Kutlar F, Wilson JB, Webber BB,

Hu H, Huisman THJ. Hb Duan [a75(EF4)Asp > Ala], Hb Westmead [a122(H5)-

His > Gln], and a-thalassemia-2 (�4.2 kb deletion) in a Chinese family. Hemo-

globin 1988; 12(1):13–21.7. Gu Y-C, Gu L-H, Wilson JB, Cepreganova B, Ramachandran M, Walker ELD III,

Thalassemia Intermedia in Chinese Family 155

Hem

oglo

bin

Dow

nloa

ded

from

info

rmah

ealth

care

.com

by

Yor

k U

nive

rsity

Lib

rari

es o

n 11

/04/

14Fo

r pe

rson

al u

se o

nly.

ORDER REPRINTS

Huisman THJ, Potitong P. Hb Westmead [a122(H5)His > Gln], Hb E [b26(B8)

Glu > Lys], and a-thalassemia-2 (3.7 kb deletion) in a Laotian family. Hemoglobin

1991; 15(4):297–302.8. Ma ESK, Chow EYD, Chan AYY, Chan LC. Interaction between (– –SEA) a-

thalassemia deletion and uncommon non-deletional a-globin mutations in Chinese

patients. Haematologica 2001; 86(5):539–540.9. Loukopoulos D, Loutradi A, Fessas P. A unique thalassaemic syndrome:

homozygous a-thalassaemia + homozygous b-thalassaemia. Br J Haematol 1978;39(3):377–389.

10. Furbetta M, Galanello R, Ximenes A, Angius A, Melis MA, Serra P, Cao A.

Interaction of a and b thalassaemia genes in two Sardinian families. Br J Haematol

1979; 41(2):203–210.11. Kanavakis E, Traeger-Synodinos J, Lafiniatis S, Liakopoulou Th, Metaxotou A,

Stamoulakatou A, Papassotiriou I. A rare and unusual thalassaemia intermedia

with co-inheritance of b-thalassaemia major and Hb H disease. Hematol J 2003;4(suppl 2):51. (abstract 0142).

Received November 22, 2003Accepted December 3, 2003

156 Wong et al.

Hem

oglo

bin

Dow

nloa

ded

from

info

rmah

ealth

care

.com

by

Yor

k U

nive

rsity

Lib

rari

es o

n 11

/04/

14Fo

r pe

rson

al u

se o

nly.

Request Permission/Order Reprints

Reprints of this article can also be ordered at

http://www.dekker.com/servlet/product/DOI/101081HEM120035917

Request Permission or Order Reprints Instantly!

Interested in copying and sharing this article? In most cases, U.S. Copyright Law requires that you get permission from the article’s rightsholder before using copyrighted content.

All information and materials found in this article, including but not limited to text, trademarks, patents, logos, graphics and images (the "Materials"), are the copyrighted works and other forms of intellectual property of Marcel Dekker, Inc., or its licensors. All rights not expressly granted are reserved.

Get permission to lawfully reproduce and distribute the Materials or order reprints quickly and painlessly. Simply click on the "Request Permission/ Order Reprints" link below and follow the instructions. Visit the U.S. Copyright Office for information on Fair Use limitations of U.S. copyright law. Please refer to The Association of American Publishers’ (AAP) website for guidelines on Fair Use in the Classroom.

The Materials are for your personal use only and cannot be reformatted, reposted, resold or distributed by electronic means or otherwise without permission from Marcel Dekker, Inc. Marcel Dekker, Inc. grants you the limited right to display the Materials only on your personal computer or personal wireless device, and to copy and download single copies of such Materials provided that any copyright, trademark or other notice appearing on such Materials is also retained by, displayed, copied or downloaded as part of the Materials and is not removed or obscured, and provided you do not edit, modify, alter or enhance the Materials. Please refer to our Website User Agreement for more details.

Hem

oglo

bin

Dow

nloa

ded

from

info

rmah

ealth

care

.com

by

Yor

k U

nive

rsity

Lib

rari

es o

n 11

/04/

14Fo

r pe

rson

al u

se o

nly.