Journal of the Neurological Sciences, 100 (1990) 137-141
Epidemiology of multiple sclerosis in Arabs in Kuwait: a comparative
study between Kuwaitis and Palestinians
A.S. Najim A1-Din 1, M. Khogali 2, C.M. Poser 3, K.E. A1-Nassar 4, R. Shakir 1, J. Hussain 1,
K. Behbahani 5 and G. Chadha
Departments of 1Medicine, 2 Community Medicine, 4 Biochemistry, s Microbiology. Faculty of Medicine, University of Kuwait, Safat (Kuwait.), and
3Department of Neurology, Harvard Medical School, Boston, MA (U.S.A.)
(Received 15 March, 1990)
(Revised, received 30 July, 1990)
(Accepted 3 August, 1990)
Key words: Multiple sclerosis; Epidemiology; Comparative study; Arabs
On December 31, 1988 there were 201 registered multiple sclerosis patients in Kuwait, an overall prevalence rate (PR) of 10.2 per
100 000; among them were 186 Arabs, of whom 72 were Palestinians and 51 Kuwaitis. Comparison of these two subgroups, who had
a similar age distribution revealed that the disease was 21/2 times more frequent among Palestinians (PR 23.8/100000) than among
Kuwaitis (PR 9.5/100000). Palestinians also showed significant differences from Kuwaitis in eye color, blood group distribution and
HLA-DR and HLA-DQW epitopes frequency. This suggests that genetic rather than environmental factors might be the underlying cause
for the high susceptibility to develop MS among Arabs originating from the Eastern Mediterranean basin.
Worldwide studies of multiple sclerosis (MS) have re-
peatedly shown that the disease is unequally distributed
(Kurtzke, 1975, 1980). Both genetic and environmental
factors seem to influence the frequency of the disease.
Surveys from the Near and Middle East (Mutlu, 1954;
Shaby, 1958; Leibowitz et al., 1972; Hamdi, 1974; Kurdi
et al., 1977; Berginer et al., 1982; Ben Hamida, 1982;
Radhakrishnan et al., 1985; A1-Din, 1986; A1-Deeb et al.,
1988; Yaqub and Daif, 1988; AI-Rajeh et al., 1989) have
demonstrated that MS is less common there than in
Western Europe and North America. A previous study
from Kuwait (AI-Din, 1986) reported an overall prevalence
rate of 8.3/100000 and showed that MS was commoner
among the Palestinian residents of Kuwait than among the
Kuwait offers an unusual opportunity for comparative
epidemiological studies of MS because of its immigrant
population from many different countries and unrestricted
access to high quality free medical services. The population
Correspondence to: Charles M. Poser, MD, Neurological Unit,
Harvard Medical School, 330 Brookline Avenue, Boston, MA 02215,
of approx. 2 million is small enough to enable personal
examination of all suspected cases, yet large enough to yield
a sizeable series of patients for biostatistical calculations.
The second largest population group, after the Kuwaitis, are
the Palestinians. In this report we examine the characteris-
tics of MS among these 2 groups and the possible genetic
and environmental factors that affect the apparent differ-
ence in disease susceptibility.
Kuwait is a small desert country occupying the north-
west comer of the Arabian Gulf, located between latitudes
28°45'N and 30 °05'N and longitudes 46 ° 30' and
48 ° 30' E of Greenwich. Its surface area is 17818 km 2
(approx. 7 000 square miles). The weather is typical of the
Sahara geographical region: winter is short and cool with
a mean maximum temperature of 17.70 ° C and a mean
minimum temperature of 7.7 ° C in January; summer is long
and hot with a mean maximum temperature of 46.6 ° C in
July; spring and fall are short. Kuwait has a mean rainfall
of 79.1 mm annually and a mean daily sunshine of 8 : 39 h.
Ninety-five percent of the residential buildings are
modern with fresh water and electricity supply. Most of the
0022-510X/90/$03.50 © 1990 Elsevier Science Publishers B.V. (Biomedical Division)
water supply comes from desalination plants. Petroleum
and petrochemical products constitute the major industry.
In the 1985 census the population of Kuwait was
1.7 million and in 1988 the projected population was
approx. 2 million of whom 40~o are Kuwaitis. Other Arabs,
among whom the Palestinians and Egyptians are the largest
groups, represent 38 }'o, Southeast Asians constitute 21 ~o,
and Europeans and North Americans constitute 1 ~,,. The
age structure of both the Kuwaiti and the Palestinian popu-
lations is similar and typical of a young developing country
with 48.6~o below the age of 15, 48~o between 16 and 60,
and only 3.4~o above 60 years of age.
Study population and methods
December 31 st, 1988 was selected as prevalence day for
the study. All MS patients who satisfied the criteria of Poser
et al. (1983) for clinically definite (CDMS), laboratory sup-
ported definite (LSDMS), clinically probable (CPMS) and
laboratory supported (LSPMS) MS, and were resident in
Kuwait for at least two years, are included in the study. The
cases were identified in the neurology services of the three
major government hospitals by the same neurologists
(A.S.N., J.H. and R.A.S.). In order to ascertain cases in
other hospitals and institutions letters were sent to all staff
internists, physiatrists, ophthalmologists and general prac-
titioners requesting referral of all cases suspected of having
MS. The medical records of all six governmental hospitals
were reviewed for possible cases of MS classified under
ICD 340 and 341 at regular intervals (1982, 1984 and
1987). The diagnosis of MS was made in all instances by
a neurologist (A.S.N., J.H. or R.A.S.).
Comparison between the Kuwaiti and Palestinian
groups were made using the normal Z-test when appro-
On prevalence day, there were 201 MS patients resident
in Kuwait (114 women and 87 men). 149 were classified as
CDMS, 13 as LSDMS, 38 as CPMS and 1 as LSPMS.
Their mean age was 34.7 (SD + 10.7) years (32.7 +_ 10.2 for
women and 35.4 + 10.3 for men). The female/male ratio
was 1.3:1. Of the 201patients,
72 Palestinians, 51 Kuwaitis, 22 Egyptians, 12 Syrians, and
24 originating from 4 other Arab countries as well as 5 non-
Kuwaiti Bedouins; 15 belonged to other ethnic groups
186 were Arabs:
COUNTRY OF ORIGIN OF MS PATIENTS ON DECEMBER 31st,
Country of origin Men Women Total
Total 87 114 201
32.9 + 9.71 (20-59)
31.2 +- 5.8 (25-43)
33.8 + 11.0 (20-59)
36.45 + 11.9 (9-61)
40.26 + 12.3 (9-61)
33.2 _+ 10.7 (15-49)
Mean age at onset
25.2 + 7.97 (13-46)
23.7+ 6.5 (14-39)
26 + 8.5 (13-46)
32.1 + 11.2 (8-53)
26.3 +- 9 (10-42)
+ 10.4 (8-53)
Of the 72 Palestinians, 51 patients had their origin in
towns and villages north and northeast of Jerusalem: 22
from the town of Tulkarim and the neighbouring villages, 15
from the adjacent town of Ram-Allah and its villages and
14 from the Nablus area. Of the 21 remaining patients, 9
each came from Jerusalem and the Gaza strip, while three
immigrated from areas south of Jerusalem. The majority
belonged to farming families prior to their migration.
Table 2 shows the age and sex specific prevalence rates
per 100000 for Kuwaitis and Palestinians. The prevalence
rate among Kuwaitis was 9.5 as compared to 23.8 among
the Palestinians, the difference is statistically highly signifi-
cant (P < .001). The prevalence rate for the Kuwaiti men
and women was 7.2 and 11.8 compared to 20.5 and 27.5 for
the Palestinian men and women respectively (P < 0.001).
The female/male sex ratios among the Kuwaitis and the
Palestinians are almost identical (1.0 and 0.9) but in
patients there is a preponderance of women in the Kuwaiti
group (1.7:1) which is greater than in the Palestinians
Familial occurrence of the disease was found in
6 Kuwaitis: a mother and her son, a male patient and his
paternal uncle and a female patient and a third degree male
cousin. This was noted in 4 Palestinian patients; 2 male
siblings and 2 first degree female cousins. Only one patient
had a dizygotic twin who was free from the disease.
AGE- AND SEX-SPECIFIC PREVALENCE RATES PER 100000 OF MS IN KUWAIT
No.* Pop. (000)* PR *
No. Pop. (000) PR
No. Pop. (000) PR
* No. = number of patients; (000) = in thousands population; PR = prevalence rate/100000.
The eye color of 100 Kuwaiti and 100 Palestinian con-
trols were recorded and compared to each other and to the
patients in the 2 groups (Table 3). Kuwaitis have black or
dark brown colored eyes more frequently and hazel colored
eyes less frequently than Palestinians. None of the Kuwaiti
patients had green or blue colored eyes whereas 10 (16~)
of the Palestinian patients had. The frequency of the
different eye colors was similar among the controls and
their respective patient groups.
Table 4 shows the distribution of the ABO and Rh blood
groups in our patients as well as among 1000 healthy con-
trols for each nationality group. The following differences
were found in the distribution of the ABO groups between
the two control groups; blood group A was more frequently
found in Palestinians, but groups B and O were less com-
monly noted than in Kuwaitis. No significant differences in
the Rh blood groups were found when comparing the
2 groups. Patients from both population groups did not
differ from their respective control groups.
COMPARISON BETWEEN EYE COLOR OF KUWAITIS AND PALESTINIANS
Eye color Kuwaitis Palestinians
Patients (n = 51)
Controls (n = 100) Patients (n = 72)
Controls (n = 100)
Black or dark brown
Green or blue
21.6 ~o **
81 ~o ***
*** P < 0.001; P < 0.01. Significant differences were found between both patients and controls in the 2 groups, but not between patients and controls
within the same group.
DISTRIBUTION (yo) OF BLOOD GROUPS IN KUWAITI AND
PALESTINIAN MS PATIENTS AND CONTROLS
(n = 42)
(n = 1000)
(n = 53)
(n = 1000)
** P < 0.01; ***P<O.O01.
The HLA-DR and HLA-DQW epitopes were studied in
27 Palestinian and 25 Kuwaiti patients and compared to 50
and 32 Palestinian and Kuwa~ti normal controls respec-
tively (Table 5). Differences existed between the two groups
of patients as well as the two control groups. An association
between MS and HLA-DR2 and HLA-DQW 1 was
significant only in Palestinians. When the frequency of
the HLA-DR and HLA-DQW epitopes were compared in
the 2 control groups, HLA-DR 2 and HLA-DQW 1 were
found to be higher in the Kuwaiti controls and the difference
was statistically significant. HLA-DQW 3 was found to be
more frequent among the Palestinian controls.
DISTRIBUTION (Yo) HLA-DR AND QW CHARACTERISTICS OF
KUWAITIS AND PALESTINIANS
(n = 27)
(n = 50)
(n = 25)
(n = 32)
0 8 0 18.7
* P < 0.05; **P < 0.02.
Shaby (1958) from Baghdad, Iraq was the first to
describe MS among Arabs. Only 13 of his 96 patients were
described as having had a classical relapsing remitting
course of disease whereas 83 had a single episode of acute
neurologic dysfunction and thus were not categorized as
MS. Hamdi (1975) in a 3-year hospital-based study during
1967-1969 identified 11 MS patients in Baghdad and re-
ported a prevalence rate of 3.4/100000 with a high fre-
quency among the non-Arab Kurdish population living in
the northern parts of Iraq. The prevalence rates of MS in
Jordan, Tunisia and Northeastern Libya were reported to
be 7, 10 and 5.9 per 100000 respectively (Kurdi et al., 1977;
Ben Hamida, 1982; Radhakrishnan et al., 1985). Yaqub
and Daif (1988) estimated the prevalence rate of MS in
S audi Arabia to be 8/100 000, based on 16 cases of M S and
10 cases of amyotrophic lateral sclerosis in a large teaching
hospital. A similar figure was stated by Al-Deeb et al.
(1988) from another referral hospital in Riyadh, but
A1-Rajeh et al. (1989) argued that the prevalence rate of MS
among native Saudis was less than that reported in these
two surveys. All these previously published surveys of MS
among Arabs were based upon hospital admissions, pre-
sumably counting only the sickest patients and therefore
suggesting that the prevalence of M S may actually be higher
than that based on these data. Among the Kuwaiti patients
the female/male ratio of 1.7 : 1 is approximately similar to
that observed among Caucasian populations (Hader et al.,
1988), but no ready explanation can be offered for the lower
ratio among Palestinian patients, except possibly for the
fact that in general there are more men among non-Kuwai-
tis. The phenomena which influence the sex ratios among
normal immigrant population as well as patients are com-
plex. Among these are the type of jobs available and the fact
that many male immigrants do not bring their families.
The findings in this study are in accordance with those
previously reported by AI-Din (1986). Palestinians have age
specific rates similar to Europeans and are likely to develop
MS 2.5 times more frequently than Kuwaitis. This differ-
ence is particularly true for the older age groups (Table 2).
An interesting but unexpected observation is that the
disease among the Kuwaitis is more frequent in the young
age groups than in the older ones (Table 2). This is unlikely
to be due to lack of reporting of cases in older age groups.
We have studied all the records of patients treated by a
consultant neurologist who practiced in Kuwait between
1971 and 1978 and all cases diagnosed by him were also
included in our registry.
It is unlikely that environmental factors alone can
account for the differences in the prevalence rates. Approxi-
mately 60yo of the Palestinians in Kuwait were born there
and the majority of the remaining 40~o migrated to Kuwait
more than 20 years ago. Incidence rates (to be published)
in the 2 groups have been roughly similar for the past
30 years and do not support the idea that MS is a "new"
disease in Kuwait. Although socioeconomic differences
exist, both groups live in the same city and have access to
the same water supply, sanitation and health facilities. Both
populations have nearly similar age structures and the rate
of consanguineous marriage was reported to be equally high
in both (AI-Nassar et al., 1989).
Genetic factors determining disease susceptibility might
provide a better explanation for the higher frequency of MS
among Palestinians compared to Kuwaitis. Many Pa-
lestinians have fairer skin color and have lighter colored
eyes than Arabs from the Gulf region. These skin and eye
color features are uncommon in Arabs except in the East
Mediterranean basin. During several millennia the Eastern
Mediterranean basin was more exposed to invasions and
population settlement. During the 2 centuries of the
Crusades, thousands of pilgrims, warriors and their families
settled in Palestine; many of them originated from northern
Europe, an area now characterized by a very high preva-
lence of the disease. It would seem logical to suspect genetic
admixing with the native Arab populations during the exis-
tence of the so-called Latin Kingdoms in the XIIth Century
A.D. (Poser, 1990). Furthermore, differences in the distri-
bution of the ABO blood groups as well as in the HLA-DR
and HLA-DQW epitopes were found in the normal popu-
lations of both groups: Palestinian MS patients had an
association with HLA-DR 2 and HLA-DQW 1 similar to
that reported in Caucasians (Batchelor et al., 1978) but no
such association was found in Kuwaitis (Table 5).
We believe that our observations strongly favor the pri-
mary role of still unknown genetic factors that determine
disease susceptibility in particular ethnic groups. Similar
observations on 2 genetically different populations sharing
the same environment have consistently shown differences
in the risk of developing MS in Israel, South Africa and
India (Alter etal., 1971; Frances and Louw, 1977;
Bharucha et al., 1988).
Acknowledgements We thank Mrs. Etcy D'Costa for her secretarial
work. This study is partly supported by grant No. Ku MM008.
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