Second case of Bardet-Biedl syndrome caused by biallelic variants in IFT74.

Bardet-Biedl syndrome (BBS) is a rare autosomal recessive disorder of the cilia, often resulting in a phenotype of obesity, rod-cone dystrophy, a variable degree of intellectual disability, polydactyly, renal problems, and/or hypogonadism in males or genital abnormalities in females. We here report the case of an 11-year-old girl who presented with postaxial polydactyly, retinal dystrophy, and childhood obesity, suggesting Bardet-Biedl syndrome. She had no renal problems, developmental delay, or intellectual disability. Genetic testing revealed compound heterozygous variants in the IFT74 gene (c.371_372del p.Gln124Argfs*9 and c.16850-1G>T p.?). We here report the second patient with Bardet-Biedl syndrome due to biallelic IFT74 variants. Both patients have obesity, polydactyly, retinal dystrophy, and no renal abnormalities. The present case however, has normal intellect, whereas the other patient has intellectual disability. We hereby confirm IFT74 as a BBS gene and encourage diagnostic genetic testing laboratories to add IFT74 to their BBS gene panels.

Determinants of postprandial plasma bile acid kinetics in human volunteers.

Bile acids (BA) are signaling molecules with a wide range of biological effects, also identified among the most responsive plasma metabolites in the postprandial state. We here describe this response to different dietary challenges and report on key determinants linked to its interindividual variability. Healthy men and women (n = 72, 62 ± 8 yr, mean ± SE) were enrolled into a 12-wk weight loss intervention. All subjects underwent an oral glucose tolerance test and a mixed-meal tolerance test before and after the intervention. BA were quantified in plasma by liquid chromatography-tandem mass spectrometry combined with whole genome exome sequencing and fecal microbiota profiling. Considering the average response of all 72 subjects, no effect of the successful weight loss intervention was found on plasma BA profiles. Fasting and postprandial BA profiles revealed high interindividual variability, and three main patterns in postprandial BA response were identified using multivariate analysis. Although the women enrolled were postmenopausal, effects of sex difference in BA response were evident. Exome data revealed the contribution of preselected genes to the observed interindividual variability. In particular, a variant in the SLCO1A2 gene, encoding the small intestinal BA transporter organic anion-transporting polypeptide-1A2 (OATP1A2), was associated with delayed postprandial BA increases. Fecal microbiota analysis did not reveal evidence for a significant influence of bacterial diversity and/or composition on plasma BA profiles. The analysis of plasma BA profiles in response to two different dietary challenges revealed a high interindividual variability, which was mainly determined by genetics and sex difference of host with minimal effects of the microbiota.NEW & NOTEWORTHY Considering the average response of all 72 subjects, no effect of the successful weight loss intervention was found on plasma bile acid (BA) profiles. Despite high interindividual variability, three main patterns in postprandial BA response were identified using multivariate analysis. A variant in the SLCO1A2 gene, encoding the small intestinal BA transporter organic anion-transporting polypeptide-1A2 (OATP1A2), was associated with delayed postprandial BA increases in response to both the oral glucose tolerance test and the mixed-meal tolerance test.