The ethnic origin of a population should be considered in Medical Examination: A study- Signatures of high altitude adaptation in Tibeto-Burman tribes of the Darjeeling Hill Region (DHR)

KalimNews, Kalimpong, 7 January 2023: Nestled in the Singalila Ridge of the Eastern Himalayas, the Darjeeling Hill Region, comprising the hilly areas of Darjeeling and Kalimpong districts, is homeland for several tribal and non tribal populations (collectively called Gorkha). 

Major chunk of the tribal populations is represented by Tamang, Limbu, Lepcha, Bhutia, Sherpa, and Tibetans. With such a diverse ethnic groups with distinct socio-cultural practices, it is necessary to study their anthropometric and biomedical parameters to understand the ethnic variations. These data are also essential for better medical diagnosis. 

Therefore, a team of Scientists involving the University of Calcutta and BHU have studied ten anthropometric and biochemical parameters of 178 individuals from four Himalayan populations - Lepcha, Bhutia, Sherpa, and Tibetans. They found that populations with high altitude ancestry have significantly low haemoglobin and high blood pressure to cope with the extreme climate. This study was published this week in the American Journal of Human Biology. 

The Himalayan population has a robust physical appearance and are surviving the challenging environment for thousands of years. The adaptation due to their genomic mutations has enabled them to utilise the prevailing less atmospheric oxygen levels and extreme cold climate. However, how these genes modulate the phenotype still needs to be discovered. 

Therefore, this team has conducted this study and measured ten parameters: body weight, height, BMI, blood pressure, pulse rate, SpO2, haemoglobin, hematocrit, and blood glucose level. On average, the high-altitude populations, Sherpa and Tibetans, had mean haemoglobin content slightly over 12 g/dl (14.9 g/dl control value), and their mean systolic and diastolic pressure was 142 mmHg (120 mmHg control value) and 94 mmHg (control value 80 mmHg)  respectively. 

The haemoglobin content was highest among Bhutia (14.13 mmHg), followed by Lepcha (13.6 mmHg). “Comparatively low haemoglobin in blood facilitates efficient blood circulation in the high altitude populations enabling them to utilize less oxygen more efficiently”, Said Dr Rakesh Tamang, the lead author of this study.

“The study supports that knowledge of ethnicity is required for the correct diagnosis of a person,” said Gyaneshwer Chaubey, one of the senior authors of this study. He further said that the Sherpa is an interesting high altitude tribe, who are best suited to thrive in the hostile high altitude environment. 

Authors have highlighted that this study is a prime example of human adaptation to a challenging environment.

The study concludes "Thus, our study showed the persistence of high altitude signatures in Tibetans and Sherpa inhabited the DHR. Additionally, we also observed significant differences in the anthropometric and physiological parameters among the Tibeto-Burman populations of the Darjeeling Hill Range."

The team consists of Saptaparni De, Divya Rai, Shishir Tamang, Soni Subba  and Rakesh Tamang of Department of Zoology, University of Calcutta,

Rinchen Doma Sherpa of Department of Neurosciences, University of Calcutta

Dup Tshering Lepcha of Pokhriabong Higher Secondary School, Darjeeling,

Periyas amy Govindaraj and Kumarasamy Thangaraj of Centre for DNA Fingerprinting and Diagnostics, Hyderabad

Gyaneshwer Chaubey of Cytogenetics Laboratory, Department of Zoology, Banaras Hindu University