BRF1 mutations in a family with growth failure, markedly delayed bone age, and central nervous system anomalies.

Linear growth failure can be caused by many different genetic abnormalities. In many cases, the genetic defect affects not only the growth plate, causing short stature but also other organs/tissues causing additional clinical abnormalities. A 10-year old boy was evaluated for impaired postnatal linear growth (height 113.3 cm, -4.6 SDS), a bone age that was delayed by 5 years, dysmorphic facies, cognitive impairment, and central nervous system anomalies. His younger brother, presented only with growth failure at 10 months of age. Exome sequencing identified compound heterozygous variants in the gene encoding RNA polymerase III transcription initiation factor 90 kDa subunit (BRF1) in both affected siblings: a missense mutation (c.875 C > G:p.P292R) and a frameshift mutation (c.551delG:p.C184Sfs). The frameshift mutation is expected to lead to nonsense-mediated mRNA decay (NMD) and/or to protein truncation. Expression of BRF1 with the P292R missense mutation failed to rescue yeast lacking BRF1. The findings confirm a previous report showing that biallelic mutations in BRF1 cause cerebellar-facial-dental syndrome. Our findings also help define the growth phenotype, indicating that the linear growth failure can become clinically evident before the neurological abnormalities and that a severely delayed bone age may serve as a diagnostic clue.

Accelerated Skeletal Maturation in Disorders of Retinoic Acid Metabolism: A Case Report and Focused Review of the Literature.

Nutritional excess of vitamin A, a precursor for retinoic acid (RA), causes premature epiphyseal fusion, craniosynostosis, and light-dependent retinopathy. Similarly, homozygous loss-of-function mutations in CYP26B1, one of the major RA-metabolizing enzymes, cause advanced bone age, premature epiphyseal fusion, and craniosynostosis. In this paper, a patient with markedly accelerated skeletal and dental development, retinal scarring, and autism-spectrum disease is presented and the role of retinoic acid in longitudinal bone growth and skeletal maturation is reviewed. Genetic studies were carried out using SNP array and exome sequencing. RA isomers were measured in the patient, family members, and in 18 age-matched healthy children using high-performance liquid chromatography coupled to tandem mass spectrometry. A genomic SNP array identified a novel 8.3 megabase microdeletion on chromosome 10q23.2-23.33. The 79 deleted genes included CYP26A1 and C1, both major RA-metabolizing enzymes. Exome sequencing did not detect any variants that were predicted to be deleterious in the remaining alleles of these genes or other known retinoic acid-metabolizing enzymes. The patient exhibited elevated plasma total RA (16.5 vs. 12.6±1.5 nM, mean±SD, subject vs. controls) and 13-cisRA (10.7 nM vs. 6.1±1.1). The findings support the hypothesis that elevated RA concentrations accelerate bone and dental maturation in humans. CYP26A1 and C1 haploinsufficiency may contribute to the elevated retinoic acid concentrations and clinical findings of the patient, although this phenotype has not been reported in other patients with similar deletions, suggesting that other unknown genetic or environmental factors may also contribute.

IL-21 modulates CD4+ CD25+ regulatory T-cell homeostasis in experimental autoimmune encephalomyelitis.

The homeostasis of CD4+ CD25+ regulatory T cells (Tregs) depends on the cytokine interleukin (IL)-2. As IL-21 shares sequence homology with IL-2 and the IL-21 receptors contain a gamma-chain common to IL-2, we hypothesized that IL-21 could also affect the homeostasis of Tregs. We tested this hypothesis in experimental autoimmune encephalomyelitis (EAE), an animal model of relapsing-remitting human multiple sclerosis. We show that blockade of IL-21 in SJL/J mice before and after the induction of EAE enhances the influx of inflammatory cells into the central nervous system (CNS). The blockade of IL-21 leads to proliferation of proteolipid peptide (PLP(139-151))-autoreactive CD4+ T cells, which are capable to cause severe EAE in adoptively transferred recipient mice. Conversely, Tregs from mice where IL-21 was blocked, lose their capacity to prevent EAE induced PLP(139-151)-reactive T cells. Notably, direct effects of IL-21 on Tregs are confirmed by studies of blockade of IL-21 in mice expressing a green fluorescent protein 'knocked' into a Foxp3 allele, in which a reduction of the number of Tregs and a downregulation of their frequency and expression of Foxp3 are observed. These data suggest a role of the IL-21/IL-21R axis in the homeostasis of Tregs in CNS autoimmunity.

Spironolactone ameliorates renal injury and connective tissue growth factor expression in type II diabetic rats.

Administration of spironolactone provides a beneficial effect in various animal models of renal injury. In this study, we investigated whether spironolactone prevents the progression of diabetic nephropathy through reduction of connective tissue growth factor (CTGF) synthesis in type II diabetic rats. In addition, we evaluated the effect of aldosterone and spironolactone on CTGF and collagen production in cultured cells. Renal functional and morphologic changes were examined in Otsuka Long-Evans Tokushima Fatty rats with or without spironolactone treatment (20 mg/kg/day) for 8 months, as well as in non-diabetic age-matched Long-Evans Tokushima Otsuka rats. Spironolactone treatment did not induce any significant differences in body weight, kidney/body weight ratio, serum creatinine concentration, blood glucose levels, or systolic blood pressure. However, urinary protein and albumin excretion were significantly decreased in the spironolactone treatment group, which was associated with amelioration of glomerulosclerosis. In addition, renal CTGF, collagen synthesis demonstrated marked decreases in the spironolactone treatment group. In cultured MC and PTC, aldosterone induced significant increases in CTGF gene expression and protein synthesis associated with increased collagen synthesis, which was abolished by prior treatment with spironolactone. However, aldosterone treatment did not induce transforming growth factor (TGF)-beta1 overproduction, and inhibition of TGF-beta1 by neutralization of TGF-beta1 protein did not significantly prevent aldosterone-induced CTGF production. These results suggest that the antifibrotic effects of spironolactone may be mediated by CTGF through a TGF-beta1-independent pathway in this animal model of diabetic nephropathy.

Multiple congenital malformation in a Holstein calf.

A 10-day-old male Holstein dairy calf with orthopaedic abnormalities was unable to stand but was alert with a suckle reflex. At necropsy, the calf showed multiple defects, including partial agenesis of the left rib plate, deformed left scapula, shortened left humerus, agenesis of the left kidney, atresia ani and scoliosis. The cause of these anomalies could not be determined. This report is the first to describe partial agenesis of ribs in a calf.