Blue horizontal branch stars in the Sloan Digital Sky Survey: II. Kinematics of the Galactic halo

We carry out a maximum-likelihood kinematic analysis of a sample of 1170 blue horizontal branch (BHB) stars from the Sloan Digital Sky Survey presented in Sirko et al. (2003) (Paper I). Monte Carlo simulations and resampling show that the results are robust to distance and velocity errors at least as large as the estimated errors from Paper I. The best-fit velocities of the Sun (circular) and halo (rotational) are 245.9 +/- 13.5 km/s and 23.8 +/- 20.1 km/s but are strongly covariant, so that v_0 - v_halo = 222.1 +/- 7.7 km/s. If one adopts standard values for the local standard of rest and solar motion, then the halo scarcely rotates. The velocity ellipsoid inferred for our sample is much more isotropic [(sigma_r,sigma_theta,sigma_phi) = (101.4 +/- 2.8, 97.7 +/- 16.4, 107.4 +/- 16.6) km/s] than that of halo stars in the solar neighborhood, in agreement with a recent study of the distant halo by Sommer-Larsen et al. (1997). The line-of-sight velocity distribution of the entire sample, corrected for the Sun's motion, is accurately gaussian with a dispersion of 101.6 +/- 3.0 km/s.Comment: 23 pages including 4 figures, 1 color; submitted to A

3-Methylglutaconic aciduria--lessons from 50 genes and 977 patients

Elevated urinary excretion of 3-methylglutaconic acid is considered rare in patients suspected of a metabolic disorder. In 3-methylglutaconyl-CoA hydratase deficiency (mutations in AUH), it derives from leucine degradation. In all other disorders with 3-methylglutaconic aciduria the origin is unknown, yet mitochondrial dysfunction is thought to be the common denominator. We investigate the biochemical, clinical and genetic data of 388 patients referred to our centre under suspicion of a metabolic disorder showing 3-methylglutaconic aciduria in routine metabolic screening. Furthermore, we investigate 591 patients with 50 different, genetically proven, mitochondrial disorders for the presence of 3-methylglutaconic aciduria. Three percent of all urine samples of the patients referred showed 3-methylglutaconic aciduria, often in correlation with disorders not reported earlier in association with 3-methylglutaconic aciduria (e.g. organic acidurias, urea cycle disorders, haematological and neuromuscular disorders). In the patient cohort with genetically proven mitochondrial disorders 11% presented 3-methylglutaconic aciduria. It was more frequently seen in ATPase related disorders, with mitochondrial DNA depletion or deletion, but not in patients with single respiratory chain complex deficiencies. Besides, it was a consistent feature of patients with mutations in TAZ, SERAC1, OPA3, DNAJC19 and TMEM70 accounting for mitochondrial membrane related pathology. 3-methylglutaconic aciduria is found quite frequently in patients suspected of a metabolic disorder, and mitochondrial dysfunction is indeed a common denominator. It is only a discriminative feature of patients with mutations in AUH, TAZ, SERAC1, OPA3, DNAJC19 TMEM70. These conditions should therefore be referred to as inborn errors of metabolism with 3-methylglutaconic aciduria as discriminative feature