MRI of congenital and developmental abnormalities of the knee.

The knee joint is the one of the most common locations for congenital and developmental musculoskeletal abnormalities. Initial imaging of the knee joint should always begin with conventional radiographs. However, evaluation of the bone marrow, cartilaginous, ligamentous, and other soft-tissue components of the knee joint are better characterized with magnetic resonance imaging (MRI). We present the MRI findings of prevalent congenital and developmental abnormalities in the paediatric knee with particular emphasis on the components of the growing skeleton.

Mitochondrial DNA analysis reveals substantial Native American ancestry in Puerto Rico.

To estimate the maternal contribution of Native Americans to the human gene pool of Puerto Ricans--a population of mixed African, European, and Amerindian ancestry--the mtDNAs of two sample sets were screened for restriction fragment length polymorphisms (RFLPs) defining the four major Native American haplogroups. The sample set collected from people who claimed to have a maternal ancestor with Native American physiognomic traits had a statistically significant higher frequency of Native American mtDNAs (69.6%) than did the unbiased sample set (52.6%). This higher frequency suggests that, despite the fact that the native Taíno culture has been extinct for centuries, the Taíno contribution to the current population is considerable and some of the Taíno physiognomic traits are still present. Native American haplogroup frequency analysis shows a highly structured distribution, suggesting that the contribution of Native Americans foreign to Puerto Rico is minimal. Haplogroups A and C cover 56.0% and 35.6% of the Native American mtDNAs, respectively. No haplogroup D mtDNAs were found. Most of the linguistic, biological, and cultural evidence suggests that the Ceramic culture of the Taínos originated in or close to the Yanomama territory in the Amazon. However, the absence of haplogroup A in the Yanomami suggests that the Yanomami are not the only Taíno ancestors.