Hereditary hemochromatosis: a literature review and case report

Early adaptive responses in the skeletal muscle of young mice with hereditary hemochromatosis

BACKGROUND

Hereditary hemochromatosis (HH) is characterized by iron overload that can cause multiple organ dysfunction primarily due to uncontrolled iron-mediated oxidative stress. Although HH leads to muscular weakness, disorder, and fatigue, the mechanism by which HH affects skeletal muscle physiology is largely unknown.

METHODS

Using Hfe knockout mice (6-7 months old), a well-defined mouse model of HH, we examined iron status in the skeletal muscle, as well as other organs. As mitochondria are key organelle for muscular function, this study also explored how molecular markers for mitochondrial function and related systems are regulated in the HH skeletal muscle using western blots.

RESULTS

Although iron overload was evident at the systemic level, only mild iron overload was observed in the skeletal muscle of HH. Of note, mitochondrial electron transport chain complex I was upregulated in the HH skeletal muscle, which was accompanied by enhanced autophagy. However, these molecular changes were not associated with oxidative stress, suggesting altered mitochondrial metabolism in the muscle in response to iron overload.

CONCLUSIONS

These early adaptive responses may be important for supporting mitochondrial health before fully developing skeletal muscle dysfunction in HH. More studies are needed to determine the role of autophagy in the HH-related muscle mitochondrial dysfunction.

Functional and biochemical responses of skeletal muscle following a moderate degree of systemic iron loading in mice

Excessive iron loading may cause skeletal muscle atrophy and weakness because of its free radical generating properties. To determine whether a clinically relevant degree of iron loading impairs skeletal muscle function, young male mice received injections of iron dextran (4 mg iron/200 µl) or 2 mM d-glucose (control) 5 days/week for 2 weeks ( n = 10/group). Systemic iron loading induced an approximate fourfold increase in the skeletal muscle nonheme iron concentration. Soleus specific tension (1, 30-250 Hz) was lower among iron-loaded animals compared with controls despite similar body mass and muscle mass. Soleus lipid peroxidation (4-hydroxynonenal adducts) and protein oxidation (protein carbonyls) levels were similar between groups. In gastrocnemius muscle, reduced glutathione (GSH) and glutathione peroxidase activity were similar but glutathione disulfide (GSSG) and the GSSG/GSH ratio were greater in iron-loaded muscle. A greater protein expression level of endogenous thiol antioxidant thioredoxin (TRX) was observed among iron-loaded muscle whereas its endogenous inhibitor thioredoxin-interacting protein (TXNip) and the TRX/TXNip ratio were similar. Glutaredoxin2, a thiol-disulfide oxidoreductase activated by GSSG-induced destabilization of its iron-sulfur [2Fe-2S] cluster, was lower following iron loading. Additionally, protein levels of α-actinin and αII-spectrin at 240 kDa were lower in the iron-loaded group. Ryanodine receptor stabilizing subunit calstabin1 was also lower following iron loading. In summary, the contractile dysfunction that resulted from moderate iron loading may be mediated by a disturbance in the muscle redox balance and from changes arising from an increased proteolytic response and aberrant sarcoplasmic reticulum Ca²⁺ release. NEW & NOTEWORTHY Although severe iron loading is known to cause muscle oxidative stress and dysfunction, the effects of a moderate degree of systemic iron loading on muscle contractile function and biochemical responses remain unclear. This study demonstrates that a pathophysiological elevation in the skeletal muscle iron load leads to force deficits that coincide with impaired redox status, structural integrity, and lower ryanodine receptor-associated calstabin1 in the absence of muscle mass changes or oxidative damage.

From Death to Health in 30 Days: A Hemochromatosis Case Report

BACKGROUND

Heredity hemochromatosis (HH) is an underdiagnosed genetic disease that can lead to life-threatening multisystem organ failure. Identifying and treating HH early can prevent the progression of the disease.

CASE PRESENTATION

For a 60-year-old white patient without obvious symptoms, it was a revelation to discover that he had HH. This patient, although receiving evidence-based care, ultimately required a liver transplant. As his condition deteriorated, the plan for this patient and his family involved working within an interdisciplinary team that included nurse practitioners and intensive care unit nurses.

DISCUSSION

The uniqueness of this case illustrates the crucial role of a health care team that persisted in differentiating the patient's diagnosis and continued to sustain both physical and emotional care throughout his hospitalization despite a poor prognosis. The patient felt support from this team during the course of his illness, from requiring life-supporting care in intensive care unit to returning home and resuming his normal activities of daily living.

HFE-associated hereditary hemochromatosis: overview of genetics and clinical implications for nurse practitioners in primary care settings

PURPOSE

HFE-hemochromatosis is one of the most common genetic disorders in the United States among Caucasians of Northern European ancestry. The purpose of this article is to discuss HFE-associated hereditary hemochromatosis (HH), including the genetics, pathophysiology, phenotype and genotype, diagnostics, and management utilizing a case-based format as an exemplar.

DATA SOURCES

Online genetic resources; professional guidelines; review; and scientific articles.

CONCLUSION

HFE-HH is an autosomal recessive disorder and two major genes C282Y and H63D are associated with HH (iron overload) susceptibility particularly C282Y/C282Y mutations. It has a variable penetrance and expression. Individuals who develop iron overload may develop broad symptoms, including joint discomfort, fatigue, decreased libido, and abdominal pain; and if left untreated, HFE-HH has the potential of developing end-organ disease including liver fibrosis, cirrhosis, and cancer; cardiac arrhythmias or heart failure; and diabetes. Suspicion of the disorder begins with personal and family history, transferrin saturation, and ferritin levels, and if high, genotyping to confirm the disorder. Management consists of correcting iron overload to prevent/delay end-organ damage often consisting of intermittent phlebotomy.

IMPLICATIONS FOR PRACTICE

Knowledge of HFE-HH is essential so that nurse practitioners can identify individuals at risk and to provide appropriate management of care and referral.

Iron overload-induced rat liver injury: Involvement of protein tyrosine nitration and the effect of baicalin

Baicalin has been reported to protect against liver injury in iron-overload mice, however, the mechanisms underlying the hepatoprotective properties of baicalin are poorly understood. In this study, we systematically studied the protective effect of baicalin on iron overload induced liver injury, as well as the underlying mechanism based on nitrative stress in rat model. We found that when iron overload rats (500mgiron/kg) were fed baicalin-containing diet (0.3% and 1% w/w) for 45days, baicalin dose dependently protected against iron overload induced liver injury, including alleviation of hepatic pathological damage, decrease of SOD activity, iron content, carbonyl content, and the thiobarbituric acid-reactive substances level in hepatic tissues. It also increased serum iron content, SH content and GPx activity, decreased serum ALT and AST activities. Immunohistochemistry and immunoprecipitation analysis revealed that baicalin could also inhibit iron overload induced protein tyrosine nitration in liver. Moreover, in iron overload rat liver, we found that baicalin decreased the iron overload increased level of glutathione-S-transferases (GSTs) expression, oxidation and nitration. These results suggest that not only oxidative stress, but also nitrative stress, is involved in iron overload induced liver injury, and the underlying mechanism might partially relate to the involvement of GSTs expression and post-translational modification. Baicalin can effectively prevent iron overload caused abnormality and can be a candidate medicine for iron overload diseases.