Genetic evidence for two founding populations of the Americas.

Genetic studies have consistently indicated a single common origin of Native American groups from Central and South America. However, some morphological studies have suggested a more complex picture, whereby the northeast Asian affinities of present-day Native Americans contrast with a distinctive morphology seen in some of the earliest American skeletons, which share traits with present-day Australasians (indigenous groups in Australia, Melanesia, and island Southeast Asia). Here we analyse genome-wide data to show that some Amazonian Native Americans descend partly from a Native American founding population that carried ancestry more closely related to indigenous Australians, New Guineans and Andaman Islanders than to any present-day Eurasians or Native Americans. This signature is not present to the same extent, or at all, in present-day Northern and Central Americans or in a ∼12,600-year-old Clovis-associated genome, suggesting a more diverse set of founding populations of the Americas than previously accepted.

Studies on the discontinuous N-oxidation of trimethylamine among Jordanian, Ecuadorian and New Guinean populations.

Whilst the majority of individuals within a British white population are able to convert greater than 90% of their dietary-derived trimethylamine to its N-oxide, outliers exist who show varying degrees of impairment. Such individuals excrete unoxidized trimethylamine in their urine and, if sufficiently compromised, may experience malodour problems (Fish-Odour Syndrome). Little information concerning this polymorphic N-oxidation process is available in other ethnic groups and the present study explores Jordanian, Ecuadorian and New Guinean populations. Subjects with a relative deficiency in N-oxidation were found in all three groups, with 1.7% (2/116) Jordanian, 3.8% (3/8) Ecuadorian and 11.0% (11/100) New Guinean excreting 80% or less of their total trimethylamine as the N-oxide. Two subjects from the Ecuadorian population (4% and 33% total trimethylamine as the N-oxide) exhibited frank trimethylaminuria. These observations suggest that a compromised ability to N-oxidize trimethylamine is detectable in several ethnic groups and that this polymorphic phenomenon may have a widespread existence.