Genetic Trisomies Discovered in Ancient Skeletons UPSC

Description

EDWARDS SYNDROME

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Context: Researchers identify chromosomal disorders in ancient human remains, including six cases of Down syndrome and one case of Edwards syndrome, marking the first instance of identifying Edwards syndrome from prehistoric remains and offering insights into ancient societies' care for individuals with genetic disorders.

Key Highlights

Discovery of Chromosomal Disorders in Ancient Individuals

Researchers have made a significant discovery of chromosomal disorders in prehistoric skeletal remains dating back approximately 5,500 years.
The findings, published in the journal Nature Communications, include six cases of Down syndrome and one case of Edwards syndrome, marking the potential first identification of Edwards syndrome in historic or prehistoric remains.

Chromosomal Trisomies Identified

Chromosomal trisomies involve individuals carrying three copies of a chromosome instead of the usual two.
Trisomy of chromosomes 21 and 18 leads to Down syndrome and Edwards syndrome, respectively.

Historical Challenges

Identifying genetic disorders in ancient individuals has been challenging without modern techniques for analyzing ancient DNA samples.
Few documented cases of Down syndrome in ancient individuals exist.

Research Methodology

Researchers screened almost 10,000 genomes from ancient human skeletal remains in Ireland, Bulgaria, Greece, Spain, and Finland.
They identified six cases of Down syndrome and one case of Edwards syndrome, mostly from individuals who died before or shortly after birth. Some cases date back to the Bronze Age (about 2,700 BCE) and the Neolithic period (about 3,500 BCE).

Societal Implications

Three cases of trisomy 21 (Down syndrome) and one case of trisomy 18 (Edwards syndrome) were found in early Iron Age Spain (800-400 BCE), suggesting a potentially higher frequency of burials of trisomy carriers in those societies.

Recognition and Care in Ancient Communities

All individuals with chromosomal disorders appear to have been cared for after death through various rituals, indicating recognition within their communities.
Some were given exceptional burials or elaborate grave goods, such as the individual in Early Iron Age Navarra, Spain, buried with bronze rings, a Mediterranean seashell, and surrounded by the remains of three sheep and/or goats.
It offers insight into how these conditions were recognized and acknowledged within past communities. It highlights the care and ritualistic treatment provided to individuals with chromosomal disorders in ancient societies.

Edwards Syndrome
Key Points	Description
What is it?	Edwards syndrome, also known as trisomy 18, is a chromosomal disorder caused by the presence of three copies of chromosome 18 instead of the usual two copies.
Causes	The extra chromosome occurs due to an error during cell division (meiosis) in the formation of sperm or egg cells. It is not caused by anything the parents did and is not inherited.
Symptoms	Physical abnormalities: Small head (microcephaly), Clenched hands with overlapping fingers, Clubfoot (feet turned inward), Heart defects, Omphalocele (abdominal wall defect), Cleft lip and/or palate, Kidney malformations. Developmental delays: Difficulty feeding and growth problems, Delayed motor skills, Intellectual disability.
Diagnosis	Prenatal diagnosis can be done through various tests like amniocentesis, chorionic villus sampling (CVS), or non-invasive prenatal testing (NIPT). After birth, diagnosis is based on physical characteristics and chromosomal analysis.
Treatment	There is no cure for Edwards’s syndrome. Treatment focuses on managing symptoms and improving the quality of life. This may include surgery for heart defects, feeding assistance, and physical and occupational therapy.
Prognosis	Most babies with Edwards’s syndrome do not survive beyond their first year. Some may live for a few years in intensive care.

Conclusion

This groundbreaking research sheds light on the presence of chromosomal disorders in ancient populations and provides a unique perspective on how these individuals were integrated into their communities.

PRACTICE QUESTION

Q. What is the primary purpose of mitosis and meiosis, respectively?

A) Mitosis - Genetic variation, Meiosis - Cell growth

B) Mitosis - Cell division for growth and repair, Meiosis - Gamete formation for reproduction

C) Mitosis - Gamete formation, Meiosis - Genetic diversity

D) Mitosis - Asexual reproduction, Meiosis - Sexual reproduction

Explain: B

Explanation:

Mitosis is responsible for cell division for growth and tissue repair, while meiosis is specifically involved in the formation of gametes for sexual reproduction.