National Approach to Premarital Diagnosis of Trait Thalassemia and Silent Carriers

doi:10.4236/ijcm.2013.42017

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International Journal of Clinical Medicine, 2013, 4, 91-95

http://dx.doi.org/10.4236/ijcm.2013.42017 Published Online February 2013 (http://www.scirp.org/journal/ijcm)

National Approach to Premarital Diagnosis of Trait

Thalassemia and Silent Carriers

Narges Beigom Mirbehbahani1, Azam Rashidbaghan2*, Maryam Mazji2, Nasser Behnampour2

1Golestan University of Medical Sciences, Gorgan, Iran; 2Hematology and Oncology Research Center, Golestan University of Medi-

cal Sciences, Gorgan, Iran.

Email: *[email protected]

Received October 6th, 2012; revised November 7th, 2012; accepted November 15th, 2012

ABSTRACT

Background: Major β-thalassemia occurs when impaired genes received by a neonate from the parents. In most of the

parents, there are no apparent clinical manifestation and they just show some impairments in hematological indices.

This study was designed to determine prevalence of minor and silent carries parents that have children suffering from

major β-thalassemia, compare it with national protocol about prevention of thalassemia. Methods: A blood sample was

taken from parents of all major thalassemic patients covered by Taleghani Hospital in Gorgan (n = 195), CBC and He-

moglobin electrophoresis were done. Data were analyzed using SPSS software. Results: Amongst 196 parents one case

have normal level of MCV, MCH, RBC, HbA, HbF and mentzer = 22.05 (0.51%) that diagnosed as alpha triplication/N

by real time PCR, RFLP informative. The means of hematological indices were based on the national protocol. Conclu-

sion: Present results showed that there are a few cases of thalassemia disorders with normal MCV, MCH, RBC,

Mentzer index and Hb electrophoresis which could be missed in routine and pre-marital screening tests, resulted in a

thalassemia child that it is possible in every screening test. Generally, indices were according to range of the national

guideline.

Keywords: Beta-Thalassemia; Silent Carrier; Hemoglobin; Electrophoresis; Hematological Tests; Thalassemia

Intermedia

1. Introduction

The inherited hemoglobin (Hb) disorders are the most

common single gene detect in men. The prevalence of

hemoglobinopathies is on the rise worldwide. This is of

special importance in developing countries where it in-

creases the burden of health care delivery system. The

abnormalities can either be quantitative (the thalassemia

syndrome) or qualitative (the hemoglobin variants) or a

combination of both. Of these, the thalassemia syn-

dromes particularly the beta thalassemias and some aloha

thalassemias are the major cause of morbidity [1].

Beta-thalassemia is the common hereditary disease all

around the world, especially in Iran. It is estimated that

900,000 thalassemia patients will born in the next com-

ing 20 years; which 95% of them will be in Asia, India and

middle east. Iran Thalassemia Association reported that

18,616 thalassemia patients live in this country that Ma-

zandaran and Fars have the most affected population [2].

Reduction or absence of beta globin chains of the

hemoglobin results in Beta-thalassemia. The beta globin

(HBB) chain gene is located on the short arm of chro-

mosome 11. Beta-thalassemia silent carrier, beta thalas-

semia trait, thalassemia intermediate and thalassemia

major are four recognized category of this condition.

Heterozygosis for beta-thalassemia will lead to beta-

thalassemia silent carrier and trait [3]. In silent carrier

often revealed mild microcytosis or a slight impairment

in B-globin synthesis on radial labeling of the globin

chains peripheral blood reticulocytes. Characteristically,

silent carriers of



-thalassemia have normal levels of

HbA2 [4]. Also silent carrier is known by normal or small

decrease in MCV and MCH and normal hemoglobin

electrophoresis [5]. This type will lead to a transfusion-

dependent baby if married with a minor thalassemia [6].

In 1969, a silent thalassemia was reported through ex-

amination not only of the hematological picture but also

of the hemoglobin status and the α/



globin synthesis

ratio; the carrier was undoubtedly the father of two tha-

lassemia intermedia patients [7] in subsequent years

many similar cases were observed that confirmed the

existence of varieties of silent thalassemia [8-12].

In these patients increased RBC count, reduced hemo-

globin level, MCV and MCH, altered erythrocyte mor-

phology and increased HbA2 level imbalance in globin

*Corresponding author.

National Approach to Premarital Diagnosis of Trait Thalassemia and Silent Carriers

synthesis with the α/



ratio greater than 1 [13]. Also they

have microcytic and hypochromic anemia, target cells,

basophilic aggregation and eliptocytosis, or can be nor-

mal appearance [14]. Hemoglobin ranges from 9 - 11

gr/dl, mean MCV is 68 fl and MCH is around 20 - 22 gr

and HbA2 is greater than 3.5 [14-16].

Thalassemia intermediate is a clinical term that de-

scribes the transfusion status of the patient. In these pa-

tients who also homozygous for beta-thalassemia muta-

tions based on family studies, a Hb concentrate of 6 - 10

gr/dl, is maintained without blood transfusions [3].

The most severe form of thalassemia is thalassemia

major that sufferer is transfusion-dependent due to severe

anemia. High risk populations are detectable in Mediter-

ranean region and screening programs are developing

there to inform them about the best decision on repro-

ductive choices associated with genetic counseling and

prenatal diagnosis [17].

National screening program for detecting carrier cou-

ples (heterozygotes) was proved in Iran from 1991 to

prevent the birth of major thalassemia, as a result of pre-

venting the marriage of carriers, informing the couples

for active participation in screening programs and genetic

counseling [18].

In Iran, the annual prevention cost is constant but an-

nual treatment costs rise year by year. National Thalas-

semia Prevention Program in the Iranian province of

Mazandaran demonstrated that an unbearable financial

burden can be prevented [19].

The main goal of the present project was determining

MCV, MCH, RBC and hemoglobin electrophoresis in

parents with thalassemia major child and evaluating that

if these parents were at the time of national screening

program could they be diagnosed as silent carriers or not

(Figure 1).

2. Materials and Methods

This was a cross-sectional descriptive study. Generally,

196 individuals of parents of thalassemia major patients

referred to Taleghani hospital of Gorgan, Iran, had been

evaluated. This research was done during 2006-2007. All

couples were married before the development of national

screening program. Invitation letters were distributed for

a free-of-charge testing as followings: MCV, MCH, RBC,

Mentzer index (MCV/RBC) and hemoglobin electropho-

resis. A check list was filled for each person. Finally, all

data were coded and entered into SPSS-15 software.

Central and distributive parameters were calculated.

3. Results

In the present study 196 parents were tested. Mean and

other parameters of studied subjects are shown in Tables

1 and 2.

Generally, among 196 persons, 194 (98.98%) cases

had 3.5% ≤ HbA2 and 2 cases had 3.5% > HbA2.

HbF was 1.2% ≤ for 129 (66%) individuals and was

1.2% > for 69 (44%) persons. Just one person (0.51% of

population) had 3% ≤ HbF and remaining individuals

had 3% > HbF.

Mentzer index > 13 was found in 45 persons (23%)

and the others had a mentzer index < 13. One of the indi-

viduals with mentzer index > 13 had 80 ≤ MCV and

about others, it was 80>. MCH for one person was 27 ≤

and for others, it was <27. HbA2 was 3.5% ≤ for 44 per-

sons of them and for one of them was 3.5%>. Among

these persons, one had 3% ≤ HbF and 3.5% ≤ HbA2 and

blood indexes were as fallowing: HbA = 92.8, HbF = 3.4,

HbA2 = 3.8, MCH = 22.85, MCV = 67.87 and RBC =

4.42.

In fact one of persons with mentzer index > 13 had

normal MCH, MCV and 3.5% > HbA2. That diagnosed

as alpha triplication/N by real time PCR, RFLP informa-

tive. The means of hematological indices were based on

the national protocol.

Finally, 194 of 196 persons had 3.5% ≤ HbA2 and

mentzer index for them was 8.09 - 18.37 with 11.99 as

the mean count. This group was thalassemia minor with

high HbA2. Just one person had 3% ≤ HbF, 3.5% ≤ HbA2

and mentzer index = 16.97 that was thalassemia minor

with high HbA2 and HbF. 2 individuals had 3.5% >

HbA2. One of them had 80 > MCV, 27 > MCH and

mentzer index = 12.78 that was thalassemia minor with

normal HbA2.

RT-PCR showed Alpha triplication/N in the affected

mother and RFLP showed IVSI-130/N model in her

husband, their thalassemic major child had IVSI-130/

Alpha triplication in RT-PCR.

4. Discussion

By researching, some studies on parents of patients with

thalassemia major were as same as this study.

Ehteram et al. (1997) reported that in parents of tha-

lassemia major patients, the mean of MCV is 60 fl and

for MCH, HbA2 and HbF are 20, 5.2 and 2.4 pg, respec-

tively [4]. In comparison to this study, our results had a

larger rang of changes. While in our study, 98.98% of

population had 3.5 ≤ HbA2 and in 1.02% of them, HbA2

was normal (3.5 > HbA2), Ehteram et al. (1997) demon-

strated that in their study, 89.5% of persons have an elec-

trophoresis disorder (3.5 < HbA2) and 10.5% of them had

normal HbA2. There is markedly note that Ehteram and

colleges didn’t find any individuals with normal HbA2,

MCV and MCH and all of cases had a disorder in hema-

tological index. Probably, all parents were in beta thalas-

semia minor with normal HbA2 [4]. But in our investiga-

tion one of the persons with normal HbA2 and hemato

National Approach to Premarital Diagnosis of Trait Thalassemia and Silent Carriers

Figure 1. National screening program produced by Department of Genetic and Cancer, Deputy Non-communicable, Office of

Disease Prevention Fight, Ministry of Health and Medical Education, Iran. *If HbA is ≥7, person will be suspected to Hbs,

HbG, HbE or HbC. It should be done acetate cellulose electrophoresis and citrate agar for definitive diagnosis.

Table 1. Hematologic indices of parents of patients with beta thalassemia.

Ranges Standard division Mode Median Mean Upper limit Lower limit Index

35.86

4.38 59.43 62.08 62.65 74.57*1

52.35

MCV

1.63 19.40 19.31 19.43 25.9*2

14.26

MCH

3.3

0.59 5.78 × 106 5.71 × 10 6 5.78 × 106 7.59 × 106 4.23 × 106

RBC

10.9 1.62 9.02 10.98 10.99 18.57 7.68 Mentzer

*1Except MCV of Alpha-triplication case that was 88.21; *2Except MCH of Alpha-triplication case that was 29.26.

National Approach to Premarital Diagnosis of Trait Thalassemia and Silent Carriers

Table 2. Central parameter and dispersion of electrophoresis index of parents of patients with beta thalassemia.

Ranges Standard division Mode Median Mean Upper limit Lower limit Index (%)

4.60

0.68 93.90 93.50 93.46 96.30 91.70

HbA1

3.90

0.80 4.70 5.20 5.18 6.90 3.00

HbA2

3.00 0.37 1.10 1.30 1.35 ×106 3.4 0.4 HbF

logical index, had 13 < mentzer index and likely was

silent carrier. Probably, this difference is variety in geo-

graphic area and frequency of gene repeating in different

populations.

Atapour et al. 1997, studied 197 parents with thalas-

semia major child in Kerman, Iran, and found MCV less

than 70 in 90%, 70 - 80 in 7.5% and upper than 80 in

2.5% (5 individuals) of population [17]. 2 of persons

with MCV upper than 80 had normal HbA2, while in our

study joust one person had 80 ≤ MCV and 27 ≤ MCH

with normal HbA2. In our results, it was shown that all

had MCV > 74.57 except for one. This exception had

normal indices and was reported as a case of alpha-trip-

lication that this result was similar to result of Atapour et

al. 1997 [20].

Gholamreza Bahrami and colleagues, 1999, evaluated

HbA2 and HbF for 38 parents with thalassemia major

patients. Their results showed more contents than our

results for these parameters and it was because of 2 per-

sons with normal HbA2 in our result while in their study

there weren’t any persons with normal HbA2. Surely,

their samples was less than our samples and probably, if

they had a larger sample size, they would find cases with

normal HbA2 [21].

In a study by Kattamis and colleagues (1997), on some

families with at least one parent with normal HbA2, 10%

of all beta thalassemia patients had normal HbA2. Fur-

thermore, some beta thalassemia patients with normal

HbA2 with normal blood indexes have been found in their

results. In this population, among 9 families, 6 of them

were kwon as silent carrier and 3 of them were thalas-

semia minor with normal HbA2 [22]. While in our study,

1.02% of beta thalassemia was with normal HbA2, 1% of

parents were normal HbA2.

There are some studies about case report of beta tha-

lassemia silent carrier in India, Italy and Albany [23-25],

but generally, silent carrier have been considered lesser.

Probably it is because of low frequency of silent carrier

in different populations.

The results of this study showed that rare cases cannot

be detected by screening system, so that alpha-triplica-

tion case was not found by screening algorithm. Thus, it

is better to consider standards of studied population in

screening. As the highest found value of MCV and MCH

for parents with thalassemic children in this research,

after omitting alpha-triplication case, was 74.57 and 25.9,

respectively, it is suggested MCV and MCH are reduced

from 80 and 27, respectively, to a lower number.

On the other hand, this delicacy has social conse-

quences so that sometimes has been resulted that men

and women prevent of marriage and finally has caused

mental disorders and failure in marriage. Also it can

make problems, especially, for girls as respect culture of

our country and although they are not patient really but

others think they are ill and these girls can not marry,

While these persons have not any prohibition for mar-

riage on the base of scientific indexes. Recommended

genetic test that are done in special center, are costly for

these persons. Meanwhile, according to obtained mod

and median for MCV and MCH (Table 1), it seems we

can use lesser value for MCV and MCH.

5. Conclusions

In the present study no case of beta-thalassemia carrier

was seen. Regardless to the alpha-triplication case, the

least MCV was 74.57 fl and the least MCH was 25.9 pg,

mean MCV was 62.65 fl and mean MCH was 19.43 pg.

Present results showed that there are a few cases of

thalassemia disorders with normal MCV, MCH, RBC,

Mentzer indices and Hb electrophoresis which could be

missed in routine and pre-marital screening tests, resulted

in a thalassemia child that it is possible in every screen-

ing test. Generally, indices were according range the na-

tional guideline.

On the other hand, according to the cultures and reli-

gious condition of Iranian population, which having a

disease is bad for a girl who is single; more attention

should be paid to definite diagnosis of such a disease

which could affect the relationships and marriage chances.

6. Acknowledgements

Authors tend to appreciate deputy of research in Golestan

Medical University for the financial support of the pro-

ject. This paper was derived from a doctorate thesis.

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