Analysis of variants and mutations in the human winged helix FOXA3 gene and associations with metabolic traits

BACKGROUND/OBJECTIVES

The forkhead factor Foxa3 is involved in the early transcriptional events controlling adipocyte differentiation and plays a critical function in fat depot expansion in response to high-fat diet regimens and during aging in mice. No studies to date have assessed the potential associations of genetic variants in FOXA3 with human metabolic outcomes.

SUBJECTS/METHODS

In this study, we sequenced FOXA3 in 392 children, adolescents and young adults selected from several cohorts of subjects recruited at the National Institute of Child Health and Human Development of the National Institutes of Health based on the availability of dual-energy X-ray absorptiometry data, magnetic resonance imaging scans and DNA samples. We assessed the association between variants present in these subjects and metabolic traits and performed in vitro functional analysis of two novel FOXA3 missense mutations identified.

RESULTS

Our analysis identified 14 novel variants and showed that the common single-nucleotide polymorphism (SNP) rs28666870 is significantly associated with greater body mass index, lean body mass and appendicular lean mass (P values 0.009, 0.010 and 0.013 respectively). In vitro functional studies showed increased adipogenic function for the FOXA3 missense mutations c.185C>T (p.Ser62Leu) and c.731C>T (p.Ala244Val) compared with FOXA3-WT.

CONCLUSIONS

Our study identified novel FOXA3 variants and mutations, assessed the adipogenic capacity of two novel missense alterations in vitro and demonstrated for the first time the associations between FOXA3 SNP rs28666870 with metabolic phenotypes in humans.

Treatment of primary defective iron-reutilization syndrome: revisited

We encountered two patients who presented with hypochromic-microcytic anemia and were refractory to iron therapy. The symptoms were suggestive of anemia of chronic disease (ACD); however, there was no evidence of any such disease, either inflammatory or malignant. These patients were reminiscent of patients originally described as having primary defective iron reutilization. The hematologic picture consisted of hypochromic-microcytic anemia, low serum iron, low to normal iron binding capacity, high serum ferritin, and increased bone marrow iron in the absence of ringed sideroblasts. These patients had symptomatic anemia and received danazol (200 mg orally) three times per day to which they responded very well with an increase of approximately 3 g in the hemoglobin concentration over 1 year and amelioration of their symptoms. Danazol was well tolerated and did not cause any virilizing side effects. Doses were lowered in maintenance after 1 year to 200 mg once per week, and responses were sustained up to 36 months of follow-up duration. In the differential diagnosis of hypochromic-microcytic anemia, especially in postmenopausal women, one has to consider this type of treatable anemia when more common types such as iron deficiency, chronic inflammation, malignancy, sideroblastic anemia, or thalassemia have been ruled out.

Postmortem tissue digoxin concentrations in infants and children

The concentrations of digoxin in tissues of premature infants, full-term infants and older children obtained at autopsy were determined by a radioimmunoassay procedure. Infants were found to have much higher concentrations in the right and left ventricle (about 190 ng/g) than older children (about 70 ng/g) and adults as reported in the literature. Renal concentrations were lower in the premature group which may be related to their limited excretory capacity for digoxin. The relatively high myocardial concentrations of digoxin found in this study suggest that the usually recommended doses for infants may be excessive.