Molecular and functional analysis identifies ALK-1 as the predominant cause of pulmonary hypertension related to hereditary haemorrhagic telangiectasia.

BACKGROUND: Mutations of the transforming growth factor beta (TGFbeta) receptor components ENDOGLIN and ALK-1 cause the autosomal dominant vascular disorder hereditary haemorrhagic telangiectasia (HHT). Heterozygous mutations of the type II receptor BMPR2 underlie familial primary pulmonary hypertension. OBJECTIVE: To investigate kindreds presenting with both pulmonary hypertension and HHT. METHODS: Probands and families were identified by specialist pulmonary hypertension centres in five countries. DNA sequence analysis of ALK-1, ENDOGLIN, and BMPR2 was undertaken. Cellular localisation was investigated by heterologous overexpression of mutant constructs in both BAEC and HeLa cells. The impact of a novel sequence variant was assessed through comparative analysis and computer modelling. RESULTS: Molecular analysis of 11 probands identified eight missense mutations of ALK-1, one of which was observed in two families. Mutations were located within exons 5 to 10 of the ALK-1 gene. The majority of ALK-1 mutant constructs appeared to be retained within the cell cytoplasm, in the endoplasmic reticulum. A novel GS domain mutation, when overexpressed, reached the cell surface but is predicted to disrupt conformational changes owing to loss of a critical hydrogen bond. Two novel missense mutations were identified in ENDOGLIN. CONCLUSIONS: The association of pulmonary arterial hypertension and HHT identifies an important disease complication and appears most common among subjects with defects in ALK-1 receptor signalling. Future studies should focus on detailed molecular analysis of the common cellular pathways disrupted by mutations of ALK-1 and BMPR2 that cause inherited pulmonary vascular disease.

Effect of starting age of physical activity on bone mass in the dominant arm of tennis and squash players.

OBJECTIVE: To determine in female tennis and squash players the effect of biological age (that is, the starting age of playing relative to the age at menarche) at which tennis or squash playing was started on the difference in bone mineral content between the playing and non-playing arms. DESIGN: Cross-sectional study. SETTING: Finnish tennis and squash federations. PARTICIPANTS: 105 female Finnish national-level players and 50 healthy female controls. MAIN OUTCOME MEASURES: Differences in bone mineral content in playing and nonplaying (dominant to nondominant) arms (proximal humerus, humeral shaft, radial shaft, and distal radius) were compared in the players and controls and among six groups of players. Players were divided into groups according to the biological age (years before or after menarche) at which their playing careers began: more than 5 years before; 3 to 5 years before; 2 to 0 years before; 1 to 5 years after; 6 to 15 years after; and more than 15 years after. RESULTS: Compared with controls (whose mean +/- SD differences in bone mineral content were 4.6% +/- 4.6%, 3.2% +/- 2.3%, 3.2% +/- 3.8%, and 3.9% +/- 4.3% at the previously noted anatomical sites), the players had a significantly (P < 0.001) larger side-to-side difference in every measured site (15.5% +/- 8.4%, 16.2% +/- 9.8%, 8.5% +/- 6.6, and 12.5% +/- 7.1%). Among players, the group differences in bone mineral content were significant (P < 0.001 to P = 0.005), with the group means clearly decreasing with increasing starting biological age of playing. The difference was two to four times greater in the players who had started their playing careers before or at menarche (lowest mean difference in bone mineral content, 10.5% +/- 7.2%; highest difference, 23.5% +/- 7.2%) than in those who started more than 15 years after menarche (lowest difference, 2.4% +/- 4.8%; highest difference, 9.6% +/- 4.9%). Adjustment for potential confounding factors (age and height) did not change these trends. CONCLUSIONS: Bones of the playing extremity clearly benefit from active tennis and squash training, which increases their mineral mass. The benefit of playing is about two times greater if females start playing at or before menarche rather than after it. The minimal level and minimum number of years of activity necessary to produce these results, the extent to which this benefit is sustained after cessation of intensive training, and the degree to which these results can be extended to other forms of physical activity and other bone sites should be studied further.