A search for β thalassemia mutations in 4000 year old ancient DNAs of Minoan Cretans

Thalassemias: From gene to therapy

Thalassemias (α, β, γ, δ, δβ, and εγδβ) are the most common genetic disorders worldwide and constitute a heterogeneous group of hereditary diseases characterized by the deficient synthesis of one or more hemoglobin (Hb) chain(s). This leads to the accumulation of unstable non-thalassemic Hb chains, which precipitate and cause intramedullary destruction of erythroid precursors and premature lysis of red blood cells (RBC) in the peripheral blood. Non-thalassemic Hbs display high oxygen affinity and no cooperativity. Thalassemias result from many different genetic and molecular defects leading to either severe or clinically silent hematologic phenotypes. Thalassemias α and β are particularly diffused in the regions spanning from the Mediterranean basin through the Middle East, Indian subcontinent, Burma, Southeast Asia, Melanesia, and the Pacific Islands, whereas δβ-thalassemia is prevalent in some Mediterranean regions including Italy, Greece, and Turkey. Although in the world thalassemia and malaria areas overlap apparently, the RBC protection against malaria parasites is openly debated. Here, we provide an overview of the historical, geographic, genetic, structural, and molecular pathophysiological aspects of thalassemias. Moreover, attention has been paid to molecular and epigenetic pathways regulating globin gene expression and globin switching. Challenges of conventional standard treatments, including RBC transfusions and iron chelation therapy, splenectomy and hematopoietic stem cell transplantation from normal donors are reported. Finally, the progress made by rapidly evolving fields of gene therapy and gene editing strategies, already in pre-clinical and clinical evaluation, and future challenges as novel curative treatments for thalassemia are discussed.

2,000 Year old β-thalassemia case in Sardinia suggests malaria was endemic by the Roman period

OBJECTIVES

The island of Sardinia has one of the highest incidence rates of β-thalassemia in Europe due to its long history of endemic malaria, which, according to historical records, was introduced around 2,600 years ago by the Punics and only became endemic around the Middle Ages. In particular, the cod39 mutation is responsible for more than 95% of all β-thalassemia cases observed on the island. Debates surround the origin of the mutation. Some argue that its presence in the Western Mediterranean reflects the migration of people away from Sardinia, others that it reflects the colonization of the island by the Punics who might have carried the disease allele. The aim of this study was to investigate β-globin mutations, including cod39, using ancient DNA (aDNA) analysis, to better understand the history and origin of β-thalassemia and malaria in Sardinia.

MATERIALS AND METHODS

PCR analysis followed by sequencing were used to investigate the presence of β-thalassemia mutations in 19 individuals from three different Roman and Punic necropolises in Sardinia.

RESULTS

The cod39 mutation was identified in one male individual buried in a necropolis from the Punic/Roman period. Further analyses have shown that his mitochondrial DNA (mtDNA) and Y-chromosome haplogroups were U5a and I2a1a1, respectively, indicating the individual was probably of Sardinian origin.

CONCLUSIONS

This is the earliest documented case of β-thalassemia in Sardinia to date. The presence of such a pathogenic mutation and its persistence until present day indicates that malaria was likely endemic on the island by the Roman period, earlier than the historical sources suggest.

Archaeogenetics in evolutionary medicine

Archaeogenetics is the study of exploration of ancient DNA (aDNA) of more than 70 years old. It is an important part of the wider studies of many different areas of our past, including animal, plant and pathogen evolution and domestication events. Hereby, we address specifically the impact of research in archaeogenetics in the broader field of evolutionary medicine. Studies on ancient hominid genomes help to understand even modern health patterns. Human genetic microevolution, e.g. related to abilities of post-weaning milk consumption, and specifically genetic adaptation in disease susceptibility, e.g. towards malaria and other infectious diseases, are of the upmost importance in contributions of archeogenetics on the evolutionary understanding of human health and disease. With the increase in both the understanding of modern medical genetics and the ability to deep sequence ancient genetic information, the field of archaeogenetic evolutionary medicine is blossoming.

A European population in Minoan Bronze Age Crete

The first advanced Bronze Age civilization of Europe was established by the Minoans about 5,000 years before present. Since Sir Arthur Evans exposed the Minoan civic centre of Knossos, archaeologists have speculated on the origin of the founders of the civilization. Evans proposed a North African origin; Cycladic, Balkan, Anatolian and Middle Eastern origins have also been proposed. Here we address the question of the origin of the Minoans by analysing mitochondrial DNA from Minoan osseous remains from a cave ossuary in the Lassithi plateau of Crete dated 4,400–3,700 years before present. Shared haplotypes, principal component and pairwise distance analyses refute the Evans North African hypothesis. Minoans show the strongest relationships with Neolithic and modern European populations and with the modern inhabitants of the Lassithi plateau. Our data are compatible with the hypothesis of an autochthonous development of the Minoan civilization by the descendants of the Neolithic settlers of the island.

5,000 years ago, the Minoans established the first advanced civilization of Europe, but their origin remains unclear. Here the authors show that the Minoans were a European population, genetically similar to other ancient European populations and to the present inhabitants of the island of Crete.