PHENYLKETONURIA AND THE PEOPLES OF NORTHERN-IRELAND

The comparison of regional patterns of recessive disease mutations is a new source of information for studies of population genetics. The an alysis of phenylketonuria (PKU) mutations in Northern Ireland shows th at most major episodes of immigration have left a record in the modem genepool. The mutation I65T can be traced to the Palaeolithic people o f western Europe who, in the Mesolithic period, first colonised Irelan d. R408W (on haplotype 1) in contrast, the most common Irish PKU mutat ion, may have been prevalent in the Neolithic fanners who settled in I reland after 4500 BC. No mutation was identified that could represent European Celtic populations, supporting the view that the adoption of Celtic culture and language in Ireland did not involve major migration from the continent. Several less common mutations can be traced to th e Norwegian Atlantic coast and were probably introduced into Ireland b y Vikings. This indicates that PKU has not been brought to Norway from the British Isles, as was previously argued. The rarity in Northern I reland of IVS12nt1, the most common mutation in Denmark and England, i ndicates that the English colonialisation of Ireland did not alter the local genepool in a direction that could be described as Anglo-Saxon. Our results show that the culture and language of a population can be independent of its genetic heritage, and give some insight into the h istory of the peoples of Northern Ireland.