Zellweger syndrome: prenatal and postnatal growth failure with epiphyseal stippling

Characterization of Severity in Zellweger Spectrum Disorder by Clinical Findings: A Scoping Review, Meta-Analysis and Medical Chart Review

Zellweger spectrum disorder (ZSD) is a rare, debilitating genetic disorder of peroxisome biogenesis that affects multiple organ systems and presents with broad clinical heterogeneity. Although severe, intermediate, and mild forms of ZSD have been described, these designations are often arbitrary, presenting difficulty in understanding individual prognosis and treatment effectiveness. The purpose of this study is to conduct a scoping review and meta-analysis of existing literature and a medical chart review to determine if characterization of clinical findings can predict severity in ZSD. Our PubMed search for articles describing severity, clinical findings, and survival in ZSD resulted in 107 studies (representing 307 patients) that were included in the review and meta-analysis. We also collected and analyzed these same parameters from medical records of 136 ZSD individuals from our natural history study. Common clinical findings that were significantly different across severity categories included seizures, hypotonia, reduced mobility, feeding difficulties, renal cysts, adrenal insufficiency, hearing and vision loss, and a shortened lifespan. Our primary data analysis also revealed significant differences across severity categories in failure to thrive, gastroesophageal reflux, bone fractures, global developmental delay, verbal communication difficulties, and cardiac abnormalities. Univariable multinomial logistic modeling analysis of clinical findings and very long chain fatty acid (VLCFA) hexacosanoic acid (C26:0) levels showed that the number of clinical findings present among seizures, abnormal EEG, renal cysts, and cardiac abnormalities, as well as plasma C26:0 fatty acid levels could differentiate severity categories. We report the largest characterization of clinical findings in relation to overall disease severity in ZSD. This information will be useful in determining appropriate outcomes for specific subjects in clinical trials for ZSD.

Hepatocyte-specific deletion of peroxisomal protein PEX13 results in disrupted iron homeostasis

Peroxisomes are organelles, abundant in the liver, involved in a variety of cellular functions, including fatty acid metabolism, plasmalogen synthesis and metabolism of reactive oxygen species. Several inherited disorders are associated with peroxisomal dysfunction; increasingly many are associated with hepatic pathologies. The liver plays a principal role in regulation of iron metabolism. In this study we examined the possibility of a relationship between iron homeostasis and peroxisomal integrity. We examined the effect of deleting Pex13 in mouse liver on systemic iron homeostasis. We also used siRNA-mediated knock-down of PEX13 in a human hepatoma cell line (HepG2/C3A) to elucidate the mechanisms of PEX13-mediated regulation of hepcidin. We demonstrate that transgenic mice lacking hepatocyte Pex13 have defects in systemic iron homeostasis. The ablation of Pex13 expression in hepatocytes leads to a significant reduction in hepatic hepcidin levels. Our results also demonstrate that a deficiency of PEX13 gene expression in HepG2/C3A cells leads to decreased hepcidin expression, which is mediated through an increase in the signalling protein SMAD7, and endoplasmic reticulum (ER) stress. This study identifies a novel role for a protein involved in maintaining peroxisomal integrity and function in iron homeostasis. Loss of Pex13, a protein important for peroxisomal function, in hepatocytes leads to a significant increase in ER stress, which if unresolved, can affect liver function. The results from this study have implications for the management of patients with peroxisomal disorders and the liver-related complications they may develop.

Vitamin D status in Saudi school children based on knowledge

BACKGROUND

The prevalence of vitamin D deficiency in the kingdom of Saudi Arabia is rising unexpectedly in every age group. Apart from several risk factors, the lack of awareness is posing a serious threat for low vitamin D levels in children as well. The aim of our study was to compare the knowledge and status of vitamin D in Saudi school children.

METHODS

Saudi students, 1188 boys (15.1 ± 2.2 years) and 1038 girls (15.1 ± 2.0 years), were recruited and a pre-designed questionnaire with regards to knowledge about vitamin D was administered. Blood samples were collected and serum 25hydroxyvitamin D (25(OH)D was measured.

RESULTS

A significantly higher percentage of boys answered correctly than girls regarding knowledge questions as sun exposure (p = 0.002, and 0.011), breastfeeding (p < 0.001) and diseases (p < 0.001). The percentage of girls was significantly higher who thought that fruits and vegetables are not rich sources of vitamin D (24.7% girls vs. 15.4% boys; p < 0.001and 29.6% girls vs. 20.9% boys p < 0.001), respectively. Boys had a higher prevalence and frequency of sun exposure than girls (p < 0.001 for both). Girls showed a significantly higher percentage of sunscreen use and full covering during sun exposure (p = 0.001 for both).Vitamin D deficiency was significantly higher in girls than boys (47.0% versus 19.4.0%; p < 0.001). Vitamin D status in boys was significantly higher than girls (p < 0.001). In girls, those who answered correctly about vitamin D related disease (p = 0.03) and sources (p = 0.015), demonstrated significantly higher vitamin D levels.

CONCLUSIONS

The awareness of vitamin D and sunlight in children needs to be improved by provision of trained physicians and school teachers. Creating more areas where girls can uncover freely during routine works and outdoor activities will help increase their vitamin D levels.