A genome-wide scan for coronary heart disease suggests in Indo-Mauritians a susceptibility locus on chromosome 16p13 and replicates linkage with the metabolic syndrome on 3q27.

Prevalence of coronary heart disease (CHD), of type 2 diabetes (T2DM) and of the metabolic syndrome are in Mauritius amongst the highest in the world. As T2DM and CHD are closely associated and have both a polygenic basis, we conducted a 10 cM genome scan with 403 microsatellite markers in 99 independent families of North-Eastern Indian origin including 535 individuals. Families were ascertained through a proband with CHD before 52 years of age and additional sibs with myocardial infarction (MI) or T2DM. Model-free two-point and multipoint linkage analysis were performed using the Mapmarker-Sibs (MLS) and maximum-likelihood-binomial (MLB) programs for autosomal markers and the Aspex program for chromosome X markers. In a second step, additional markers were studied to increase the genetic map density in three regions on chromosomes 3, 8 and 16 where initial indication for linkage was found. Our data show suggestive linkage with CHD on chromosome 16p13-pter with the MLS statistics at 8.69 cM (LOD = 3.06, P = 0.00017) which partially overlaps with a high pressure (HBP) peak. At the same locus, a nominal indication for linkage with T2DM was found in 35 large T2DM Pondicherian families also having Indian origin. With respect to region 8q23, we found suggestive linkage with T2DM (LOD = 2.55, P = 0.00058) as well as with HBP. On 3q27, we replicated previous indication for linkage found in Caucasians (for the metabolic syndrome and for diabetes) according to the categorized trait for CHD and MI with the MLB statistics (LOD = 2.13, P = 0.0009). The genome scan also revealed nominal evidence of linkage with CHD on 10q23 (LOD = 2.06, P = 0.00188). Interestingly, we detected in the same region overlapping linkages with three QTLs: age of onset of CHD (LOD = 2.03), HDL cholesterol (LOD = 1.48) and LDL/HDL ratio (LOD = 1.34). Ordered-subset analysis based on family body mass index ranking replicated finding on 2q37 for T2DM (at Calpain 10 locus). These results show the first evidence for susceptibility loci that predispose to CHD, T2DM and HBP in the context of the metabolic syndrome.

Physiologic variations of the internal jugular vein surface, role of the omohyoid muscle, a preliminary echographic study.

The action of the omohyoid muscle on the hemodynamics of the internal jugular vein is controversial. For some authors, contraction of this muscle, by tightening the cervical fascia, promotes jugular venous return. For others, contraction of this muscle compresses the jugular vein in its cervical path. With this latter point in mind, the hemodynamics of the internal jugular vein have been studied in its cervical path by echography in 10 healthy volunteers. One hundred twenty measurements of the venous surface were made at rest, with the mouth open and during deep inspiration. In the last 2 situations, evidence of a significant increase in the venous surface was found above the omohyoid muscle. These data confirm the role of compression of the vein by the omohyoid muscle, leading to modifications in intracerebral venous hemodynamics, which can be affected in yawning.

Tuberculous aneurysm of the descending thoracic aorta.

Tuberculous aneurysm of the descending thoracic aorta is a rare entity. To our knowledge the present case is the sixth on record to have been successfully treated surgically. These aneurysms present the usual difficulties of surgical therapy of the thoracic aorta: spinal cord and renal circulatory protection and the choice between distant or in situ revascularization. This case is of particular interest for its evolution and its treatment: resection of the aneurysm without shunting and insertion of a graft in situ covered by a flap of omentum.