|Year : 2021 | Volume
| Issue : 1 | Page : 1-5
Prevalence of sickle cell: A study from tribal rural western Maharashtra, India
Neha Satam1, VW Patil2, Deepa Garg1, Thankamani Marar1
1 School of Biotechnology and Bioinformatics, D Y Patil University, Navi Mumbai, India
2 Department Of Biochemistry, Grant Government Medical College and Sir J. J. Groups of Hospital Mumbai, Navi Mumbai, India
|Date of Submission||23-Oct-2020|
|Date of Acceptance||19-Apr-2021|
|Date of Web Publication||24-Nov-2021|
School of Biotechnology and Bioinformatics, D. Y. Patil Deemed to be University, Sector 15, CBD Belapur, Navi Mumbai – 400 614, Maharashtra.
Source of Support: None, Conflict of Interest: None
Background: Sickle cell disease (SCD) is a common and neglected inherited disorder in the Indian tribal and nontribal population. Prevalent in scheduled populations, these are socioeconomically disadvantaged communities. SCD pathogenesis is widely studied at national and international levels which are limited to pain episodes and vaso–occlusive crisis. Objectives: In the present study, we studied the prevalence of SCD in tribal and rural population from Palghar. Materials and Methods: Subjects from primary health centers of Palghar, Maharashtra, were included in this study. Informed written consent was obtained from the all subjects. The investigation was done by solubility test and high–performance liquid chromatography, along with complete blood count. Results: Population is divided into three groups: sickle cell homozygous (HbSS), sickle cell heterozygous (HbAS), and control (HbAA). In the sample size of 5000 subjects, 1% sample was found to be affected by SCD (HbSS) and 4.08% were sickle cell heterozygous (HbAS). Comparison among hemolytic events versus vaso–occlusive single events suggests that hemolytic events, pallor and yellow sclera, counted more than other single vaso–occlusive event. Detailed screening and awareness will be the key to early intervention to reduce morbidity and mortality due to SCD. Conclusions: As SCD is becoming an increasing health concern within India, identification and creating awareness is of paramount importance. In this pilot study, heterozygous and homozygous for the sickle cell gene were explained and it is clear that SCD is a major hemoglobinopathy among the tribal people of Palghar. Further in–depth study is necessary for a proper understanding of pathogenesis of SCD.
Keywords: Awareness, hemolytic events, population, prevalence, sickle cell, vaso–occlusive event
|How to cite this article:|
Satam N, Patil V W, Garg D, Marar T. Prevalence of sickle cell: A study from tribal rural western Maharashtra, India. D Y Patil J Health Sci 2021;9:1-5
|How to cite this URL:|
Satam N, Patil V W, Garg D, Marar T. Prevalence of sickle cell: A study from tribal rural western Maharashtra, India. D Y Patil J Health Sci [serial online] 2021 [cited 2023 Jan 31];9:1-5. Available from: http://www.dypatiljhs.com/text.asp?2021/9/1/1/331106
| Introduction|| |
Sickle cell disease (SCD) is a genetic disorder, owing to substitution of the valine in the position of glutamic acid at 6th position of the hemoglobin beta chain. Research in the field of sickle cell disorder in India is still not adequate.
The present study aimed to find out the prevalence of sickle cell genes in the tribal population. Along with the study, theoretical aspects of two important types of pathogenesis i.e., hemolysis type or vaso–occlusive crisis, were considered for differentiation of SCD phenotypes.
| Materials and Methods|| |
The study was conducted in rural area of Palghar district from August 2015 to August 2017. Palghar district has eight tehsils, namely Palghar, Vada, Vikramgad, Jawhar, Mokhada, Dahanu, Talasari, and Vasai–Virar. Each tehsil was selected by proportional randomization. The population was screened by holding camps in each village with help of local social workers and teachers. The propaganda was made by word of mouth, loudspeakers, and by beating drums. Local leaders were taken into confidence. The population was first screened by a solubility test. Solubility positive samples were further quantified by using high–performance liquid chromatography (HPLC) (VARIANTTM β–thalassemia Short Program [Bio–Rad]). Red blood cell (RBC) morphology study was conducted by autoanalyzer. Family studies by pedigree analysis from all available data were also carried out for final confirmation of sickle cell homozygous patients and sickle cell heterozygous carriers. We have followed the ethical guidelines of 1975 Declaration of Helsinki and informed consent was obtained from all subjects. IEC clearance was obtained for work.
Genotype results and counseling
The subjects with abnormal genotypes were given cards displaying name, age/date of birth, village/school, and genotype AS (yellow card)/SS (red card) and a single page leaflet with simple information on the importance of premarital testing of prospective partners. The abnormal genotype cards were distributed by the counselor who gave additional information and answered queries. Cards were also given to subjects with a presumed normal AA (white card) hemoglobin phenotype.
| Results|| |
A total of 5000 subjects were screened by solubility test out of which approximate 450 samples were found positive for solubility test. All solubility positive samples were cross–checked with HPLC method. For the current study, only 500 samples were taken into consideration out of which 49 samples were with sickle cell anemia (HbSS) and 201 samples were with heterozygous sickle cell trait (HbAS) [Table 1]. These frequencies deviate significantly (P = 0.001) from that expected by the Hardy–Weinberg equilibrium. Analysis of age distribution [Table 2] showed that the age group of 0201310 years had a smaller representation compared with other age groups. The sickle cell trait prevalence increased significantly with age, but no age–related trend occurred with SS disease. In the sample size of 5000 subjects, 1% sample was found to be affected by sickle cell disease (HbSS) and 4.08% were sickle cell heterozygous (HbAS). Clinical events of SCD subjects were categorized into hemolytic crisis and vaso–occlusive crisis. Cross–sectional data of hemoglobin levels of all carriers and normal population were grouped as per the WHO grading system for anemia [Table 3] and [Table 4]. Inherent moderate anemia in the community was correlated with clinical events of SCD cases to assess the possible contribution [Table 2] and [Table 5].
|Table 2: Age–wise distribution showing the prevalence of sickle cell anemia in the selected population|
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|Table 5: Red blood cell morphology in control sickle trait and SCD subjects|
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All subjects in our study were belongs to schedule tribes (Warli, Kakari, Malhar Koli, Dhor Koli Vanjari, Wadwal) and schedule caste (Buddhist and Mahar) and scheduled caste (Buddhist and Mahar). Previous studies[5–7] have reported that SCD is more prevalent in scheduled tribes, scheduled caste, and few in other backward castes.
Percent hemoglobin (Hb%) [Table 1] was found significantly (P < 0.001) decreased in SCD subjects compared to control. All subjects were grouped into anemia classes based on hemoglobin level according to the WHO guidelines. Among the offspring of people with the sickle cell trait, the mean Hb reported was 10.8%. In our studies, subjects with SCD reported a history of weakness; breathlessness associated with low Hb% and other clinical features. RBC and platelet count of SCD subjects was significantly lower than that of sickle cell traits and control. Pathak et al. reported that the decrease in mean RBC count in AS (Trait) was statistically significant, but our population did not show a significant decrease. The mean RBC count in SCD was found to be 2.97 million/mm3 in our study which in accordance with other studies.RBC indices such as hematocrit, mean cell volume, mean corpuscular hemoglobin (MCH), and MCH concentration value in SCD subjects decreased significantly (P < 0.001) as compared to sickle cell trait and controls, as was also reported by other studies.,,
Cross sectional clinical findings [Figure 1] suggest that hemolytic events, pallor (35 SCD cases) & yellow sclera (31 SCD cases) were found to be more than any other clinical event. Vaso occlusion based pathogenesis which were noted as joint pain (24 SCD cases), chest pain (12 SCD cases), abdominal pain (10 SCD cases), pain episodes (13 SCD cases), palpable spleen (7 SCD cases), palpable liver (2 SCD cases), and ulcer manifestation (8 SCD cases). As indicated in [Table 5] there is significant (P<0.001) change in RBC morphology in all age groups of homozygous and heterozygous subjects.
|Figure 1: Clinical spectrum categorized in two phenotypes. Number of subjects are mention on X–axis and types of events on Y–axis|
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| Discussion|| |
The global burden of SCA is increasing due to improved survival rate and population migrations with the annual number of SCA newborns expected to increase from ~300,000 to more than 400,000 between 2010 and 2050. Majority of these births will occur in Sub–Saharan Africa. However, some of the highest βS allele frequencies have also been reported in Indian populations., These tribes are greatly dependent on the forest for their daily needs, including food, shelter, instruments, medicine, and even clothing. As a result of these geographical and social barriers, relatively few primary and specialty care health amenities exist in tribal zones, and there is a yawning inequality in the health status of tribals, as compared to those in urban areas. Therefore, the need of a quick and affordable screening is essential. In the present study, solubility test was used as a screening test, as it is a rapid method and easy to be carried out in the field setting. Kate and Bankar have also suggested that the solubility test can be used as a sensitive and cheaper screening test. Later, the positive samples were confirmed and Hb quantified by HPLC.
Prevalence of sickle cell disease in Palghar region was found to be 1%. From previous studies,[17–19] it was reported that sickle cell gene is widely spread in all districts of eastern Maharashtra (known as Vidarbha region), North Maharashtra (Satpura ranges), and some parts of Marathwada region., Still, complete data from western part of Maharashtra are lacking. Our results vary from previous studies, which may be attributed to the differences in the study design.
The current study illustrates that genotype detection is feasible on a substantial scale with limited resources. Screening by the solubility test with confirmation of genotype by HPLC method can provide a clear picture about the presence of other hemoglobins. Presence of the HbS gene, and although this is clearly the dominant abnormal hemoglobin in central India, it will not detect the less frequent abnormal hemoglobins such as HbD Punjab or HbE. We may be able to detect the presence of beta–thalassemia trait by HPLC which is also widespread in India. Balgirha reported the prevalence of thalassemia among tribal groups averaging 6%–18% depending on sample selection and geographic area., However, we excluded thalassemic samples from our studies. We were able to properly quantify HbF % which is one of the important markers to understand disease severity. Our results show that there is a significant increase in HbF levels in sickle cell homozygous subjects. A similar study of 91 patients from Maharashtra state also reported the presence of high HbF levels.
In the current study, more cases of sickle cell homozygous were found in the age group of 0–20 years. From this, we may conclude that life span of SCD subjects is up to 20 years; in some conditions, it may extend till the age of 30. Later stage mortality rate is very less. Similarly, the number of sickle cell trait (heterozygous) subjects was found more in young generation (i.e., 11–30 years). Heterogeneities are observed within scheduled populations, with carrier subjects ranging from ~1% to 40%., This is the crucial factor because this may lead to give birth of more SCD subjects in future. The lack of awareness and consanguineous marriage are common in this area, aggravating the issue.
Crucial to the success of this study is the education and counseling delivered to carriers of abnormal genotypes. Even in established relationships where both parents have the sickle cell trait, the chances of a child with SS disease are only 1 in 4 for each pregnancy, implying that there is a 75% chance of a healthy child. Educating them about the role of prenatal diagnosis, another option, which is becoming more widely available and acceptable in India, may help in decreasing the incidences of SCD. Fetal cells, either from the chorion or amniotic fluid, can be used to ascertain the genotype of the fetus at 12–14 weeks of pregnancy, allowing the option of termination if desired. Variable sickle cell–related pain, the frequency, location, duration, severity, and character of pain differ both within and among patients. The painful event is not synonymous with vaso–occlusion. Pain can be precipitated by many events including cold, dehydration, infection, and stress. However, the majority of painful episodes have no as yet identifiable triggers. In our studies, hemoglobin levels in control and SCD subjects indicate that moderate anemia is most abundant in this geographic location and in all other studied variables in homozygous SCD cases, frequency of hemolysis–based clinical events, i.e., pallor and yellow sclera, was found to be more that of any other vaso–occlusion–based single clinical event.
| Conclusions|| |
The present study has screened only a very small population of this region. It can be considered as a pilot study, for detecting those heterozygous and probably homozygous for the sickle cell gene. It is clear that this is a major hemoglobinopathy among the tribal people of Palghar. The education and counseling given to carriers of the HbS gene during marriage may influence arranged marriages and consequently reproductive decisions. Those detected with sickle cell disease require clinical documentation. Further need of biochemical analysis of RBCs as well as molecular insight into this studied population is required to understand correct pathogenesis and disease severity for successful management. Outreach programs by the government are necessary for better management and control of the disease.
We are thankful to School of Biotechnology and Bioinformatics, D. Y. Patil Deemed to be University, Navi Mumbai, and Grand Medical College and Sir J. J. Groups of the Hospitals, Byculla Mumbai, for providing the research facility to carry out this work.
Financial support and sponsorship
This study was self–funded.
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]