Presence of accessory abductor digiti minimi muscle in two cadavers

During routine cadaveric dissection, accessory hypothenar muscles were incidentally discovered in two cadavers, both males, aged 86 and 92. Both muscles originated from the palmaris longus tendon in the distal portion of the forearm and were identified as accessory abductor digiti minimi (AADM) muscles, based on their association with abductor digiti minimi. While AADM is a common variant in the antebrachium, it is less typical for them to originate from the palmaris longus tendon. The presence of such an AADM could complicate surgical procedures requiring resection of the palmaris longus tendon. Moreover, the surrounding neurovasculature - namely the ulnar nerve as it passes through the ulnar canal between the pisiform and hook of the hamate - could be compressed by contractions of an AADM with such a proximal origin. This can manifest as ulnar neuropathies resulting in pain, weakness, or protracted flexion of the fourth and fifth digits (ulnar claw). Our description of these muscles adds to previous accounts of variation of the palmaris longus and abductor digiti minimi muscles while considering potential clinical implications.

Effects of a selective androgen receptor modulator (SARM), GSK2849466A, on stress urinary incontinence and bladder activity in rats with ovariectomy-induced oestrogen deficiency

OBJECTIVES

To report the effect of a selective androgen receptor modulators (SARMs) on the urethral continence mechanisms in a rat model of stress urinary incontinence (SUI) induced by bilateral ovariectomy (OVX).

MATERIALS AND METHODS

Female Sprague-Dawley rats with bilateral OVX were used. Rats were divided into five groups; sham operated, vehicle-treated OVX, low-dose SARM-treated OVX (GSK2849466A: 0.005 mg/kg/day, per os [p.o.]), high-dose SARM-treated OVX (GSK2849466A: 0.03 mg/kg/day, p.o.) and dihydrotestosterone (DHT)-treated OVX (1 mg/kg/day, subcutaneous) groups. After 4 weeks of SARM treatments or 3 weeks of DHT treatment (6 weeks after OVX), rats were subjected to evaluation of the sneeze-induced continence reflex using microtransducer-tipped catheter methods, sneeze-induced leak-point pressure, and continuous cystometry measurements, followed by histological analyses of urethral tissues.

RESULTS

(i) OVX significantly impaired urethral continence function after 6 weeks to induce SUI during sneezing. (ii) Low-dose SARM treatment restored urethral baseline pressure (UBP) without affecting the amplitude of urethral response during sneezing (A-URS), partially reversing OVX-induced SUI during sneezing. (iii) High-dose SARM treatment reversed decreases in both UBP and A-URS, more effectively preventing SUI during sneezing. (iv) DHT treatment only restored A-URS without affecting UBP, partially preventing OVX-induced SUI during sneezing. (v) The high-dose SARM treatment induced hypertrophy of the striated and smooth muscle around the urethra. (vi) SARM treatment did not affect bladder function in sham or OVX rats.

CONCLUSION

Treatment with SARMs could be a more effective modality for the treatment of SUI than DHT, without affecting bladder function, by enhancing smooth- and striated muscle-mediated urethral function under stress conditions such as sneezing.

Relationships of serum free thyroxine and erythrocyte measures in euthyroid HFE C282Y homozygotes and control subjects: the HEIRS study

Hemoglobin (Hb) levels and mean corpuscular volume (MCV) are abnormal in some persons with hemochromatosis or thyroid disorders. We sought to determine whether serum free thyroxine (T4) affects erythrocyte measures in euthyroid adults with or without C282Y homozygosity. We evaluated 488 white HFE C282Y homozygotes and controls (no HFE C282Y or H63D; normal serum iron measures) identified in screening; we excluded those with thyroid disorders, anemia, erythrocytosis, or serum ferritin (SF) <34 pmol/l. In the remaining 141 C282Y homozygotes and 243 controls, we evaluated correlations of log(10) free T4 with Hb, RBC, MCV, and red blood cell distribution width (RDW). C282Y homozygotes had lower mean age, higher mean Hb, MCV, and log(10) SF, and lower mean RBC and RDW than controls; mean log(10) free T4 did not differ significantly. In HFE C282Y homozygotes, there was no significant correlation of log(10) T4 with erythrocyte measures. In controls, there was a positive correlation of log(10) T4 with Hb (P = 0.0096) and a negative correlation with RDW (P = 0.0286). Among euthyroid white adults without iron deficiency, there are significant correlations of log(10) free T4 with Hb and RDW in controls, but not in HFE C282Y homozygotes.

Early age-of-onset iron overload and homozygosity for the novel hemojuvelin mutation HJV R54X (exon 3; c.160A-->T) in an African American male of West Indies descent

An African American male of West Indies descent was diagnosed to have elevated transferrin saturation, hyperferritinemia, severe iron deposition in hepatocytes, and hepatic cirrhosis at age 4. He was treated with serial phlebotomy to maintain a normal serum ferritin concentration thereafter. We evaluated him at age 23 and confirmed that he had normal serum ferritin levels, severe iron deposition in hepatocytes, hepatic cirrhosis, and portal hypertension. He did not have endocrinopathy, cardiomyopathy, or arthropathy. He was homozygous for the novel hemojuvelin (HJV) premature stop-codon mutation R54X (exon 3; c.160A-->T). He did not have either HFE C282Y, H63D, or S65C, or deleterious coding region mutations of SLC40A1, TFR2, or HAMP. His erythrocyte measures and hemoglobin electrophoresis were consistent with alpha-thalassemia trait. We conclude that homozygosity for HJV R54X accounts for his severe, early age-of-onset hemochromatosis; his phenotype was probably modified by serial phlebotomy therapy.

A genome-wide linkage scan for iron phenotype quantitative trait loci: the HEIRS Family Study

Iron overload phenotypes in persons with and without hemochromatosis are variable. To investigate this further, probands with hemochromatosis or evidence of elevated iron stores and their family members were recruited for a genome-wide linkage scan to identify potential quantitative trait loci (QTL) that contribute to variation in transferrin saturation (TS), unsaturated iron-binding capacity (UIBC), and serum ferritin (SF). Genotyping utilized 402 microsatellite markers with average spacing of 9 cM. A total of 943 individuals, 64% Caucasian, were evaluated from 174 families. After adjusting for age, gender, and race/ethnicity, there was evidence for linkage of UIBC to chromosome 4q logarithm of the odds (LOD) = 2.08, p = 0.001) and of UIBC (LOD = 9.52), TS (LOD = 4.78), and SF (LOD = 2.75) to the chromosome 6p region containing HFE (each p < 0.0001). After adjustments for HFE genotype and other covariates, there was evidence of linkage of SF to chromosome 16p (LOD = 2.63, p = 0.0007) and of UIBC to chromosome 5q (LOD = 2.12, p = 0.002) and to chromosome 17q (LOD = 2.19, p = 0.002). We conclude that these regions should be considered for fine mapping studies to identify QTL that contribute to variation in SF and UIBC.

Evaluation of glycosaminoglycans content and 5-hydroxytryptamine 2B receptor in the heart valves of Sprague-Dawley rats with spontaneous mitral valvulopathy – A possible exacerbation by dl-amphetamine sulfate in Fischer 344 rats?

Spontaneous valvulopathy has been described as nodular or segmental thickenings composed of fibromyxoid tissue in the subendocardium of various valve-leaflets in aging rats, but its pathogenesis and significance are incompletely understood. In this study, we examined the 5-hydroxytryptamine 2B receptor (5HT2BR) expression and characterization of extracellular matrix (ECM) components, and related these to the presence of valvulopathy in the mitral valve-leaflet (spontaneous mitral valvulopathy, SMV) of Sprague-Dawley (SD) rats. We also examined hearts from Fischer 344 (F344) rats treated with dl-amphetamine sulfate for 103 weeks to further explore the potential for drug-induced exacerbation of SMV. In SD rats, valve-leaflets with SMV exhibited a greater valve thickness, a higher amount of glycosaminoglycans, a lower amount of collagen and increased number of 5HT2BR-positive cells. Our data on morphology and ECM changes showed a striking similarity between SMV in SD rats and anorexigen-associated valvulopathy in humans, and increased 5HT2BR-positive cells in SMV implies that 5HT2BR may play a role in pathogenesis. Further, increased incidence and severity of SMV in F344 rats by treatment with dl-amphetamine suggest that a drug-induced exacerbation of SMV may exist in rats. However, additional research is needed to confirm a role for 5HT2BR in the pathogenesis of SMV in SD rats, and to further characterize the relationship between dl-amphetamine treatment and exacerbation of SMV in F344 rats.

Initial screening transferrin saturation values, serum ferritin concentrations, and HFE genotypes in Native Americans and whites in the Hemochromatosis and Iron Overload Screening Study

We compared initial screening transferrin saturation (TfSat) and serum ferritin (SF) phenotypes and HFE C282Y and H63D genotypes of 645 Native American and 43,453 white Hemochromatosis and Iron Overload Screening Study participants who did not report a previous diagnosis of hemochromatosis or iron overload. Elevated measurements were defined as TfSat >50% in men and >45% in women and SF >300 ng/ml in men and >200 ng/ml in women. Mean TfSat was 31% in Native American men and 32% in white men (p = 0.0337) and 25% in Native American women and 27% in white women (p < 0.0001). Mean SF was 153 microg/l in Native American and 151 microg/l in white men (p = 0.8256); mean SF was 55 microg/l in Native American women and 63 microg/l in white women (p = 0.0015). The C282Y allele frequency was 0.0340 in Native Americans and 0.0683 in whites (p < 0.0001). The H63D allele frequency was 0.1150 in Native Americans and 0.1532 in whites (p = 0.0001). We conclude that the screening TfSat and SF phenotypes of Native Americans are similar to those of whites. The allele frequencies of HFE C282Y and H63D are significantly lower in Native Americans than in whites.

A previously undescribed frameshift deletion mutation of HFE (c.del277; G93fs) associated with hemochromatosis and iron overload in a C282Y heterozygote

A 62-year-old white man with a hemochromatosis phenotype was found to be heterozygous for the C282Y mutation of the HFE gene. The H63D and S65C mutations of HFE were not present. As most C282Y heterozygotes do not develop a hemochromatosis phenotype, the coding region of the patient's HFE gene was sequenced and a previously undescribed frameshift mutation was identified in exon 2 (c.del277; G93fs) that resulted in a premature stop-codon. There were no coding region mutations of the ferroportin gene (FPN1). We performed human leukocyte antigen (HLA) typing of the patient and his brother who was heterozygous for the C282Y HFE mutation unassociated with a hemochromatosis phenotype. They shared only C282Y and the HLA haplotype A*03, B*14; hence, the c.del277 mutation was linked to the HLA haplotype A*02, B*44 and therefore not on the same chromosome as the C282Y mutation. Thus, the present patient's only intact HFE protein is C282Y, and this may explain his hemochromatosis phenotype.

Measurement of day and night neutrino energy spectra at SNO and constraints on neutrino mixing parameters

The Sudbury Neutrino Observatory (SNO) has measured day and night solar neutrino energy spectra and rates. For charged current events, assuming an undistorted 8B spectrum, the night minus day rate is 14.0%+/-6.3%(+1.5%)(-1.4%) of the average rate. If the total flux of active neutrinos is additionally constrained to have no asymmetry, the nu(e) asymmetry is found to be 7.0%+/-4.9%(+1.3%)(-1.2%). A global solar neutrino analysis in terms of matter-enhanced oscillations of two active flavors strongly favors the large mixing angle solution.

Direct evidence for neutrino flavor transformation from neutral-current interactions in the Sudbury Neutrino Observatory

Observations of neutral-current nu interactions on deuterium in the Sudbury Neutrino Observatory are reported. Using the neutral current (NC), elastic scattering, and charged current reactions and assuming the standard 8B shape, the nu(e) component of the 8B solar flux is phis(e) = 1.76(+0.05)(-0.05)(stat)(+0.09)(-0.09)(syst) x 10(6) cm(-2) s(-1) for a kinetic energy threshold of 5 MeV. The non-nu(e) component is phi(mu)(tau) = 3.41(+0.45)(-0.45)(stat)(+0.48)(-0.45)(syst) x 10(6) cm(-2) s(-1), 5.3sigma greater than zero, providing strong evidence for solar nu(e) flavor transformation. The total flux measured with the NC reaction is phi(NC) = 5.09(+0.44)(-0.43)(stat)(+0.46)(-0.43)(syst) x 10(6) cm(-2) s(-1), consistent with solar models.

HFE genotype frequencies in consecutive reference laboratory specimens: comparisons among referral sources and association with initial diagnosis

We quantified HFE genotype frequencies in specimens submitted by physicians grouped by specialty and determined associations of genotypes with initial diagnosis based on phenotyping in patients evaluated at an iron disorders center. Of 526 specimens (519 from Alabama), these "typical" hemochromatosis-associated genotypes were detected: 85 C282Y/C282Y, 50 C282Y/H63D, and 27 H63D/H63D. Respective frequencies of C282Y/C282Y in specimens from an iron disorders center (n = 156), gastroenterologists (n = 147), hematologists/medical oncologists (n = 85), liver transplant surgeons (n = 11), endocrinologists and rheumatologists (n = 9), and "other sources" (n = 7) were greater (p < 0.05) than in population controls. In 44 patients from an iron disorders center initially diagnosed as "presumed hemochromatosis," 27 (61.4%) had C282Y/C282Y, 10 (22.7%) had C282Y/H63D, and 3 (6.8%) had H63D/H63D. C282Y/C282Y was not detected in 48 patients with "abnormality probably not an iron overload disorder." A total of 20.5% of 44 family members of patients had "typical" hemochromatosis-associated HFE genotypes (7.0% controls; p = 0.02). We conclude that most physicians who submitted specimens identify patients by phenotyping who have greater frequencies of "typical" hemochromatosis-associated HFE genotypes than controls, and that HFE mutation testing is useful in detecting hemochromatosis in family members of persons with hemochromatosis or iron overload.

HFE mutations in African-American women with non-insulin-dependent diabetes mellitus

The aim of this study was to compare the frequencies of HFE mutations in African-American women with non-insulin-dependent diabetes mellitus (NIDDM) to that of controls and to determine whether these mutations are associated with NIDDM and iron overload. We studied 167 African-American women with NIDDM. The 71 non-diabetic controls were African-American female controls. HLA-A and -B typing and HFE mutation analysis for C282Y and H63D alleles were performed using standard molecular genetic techniques. The frequencies of C282Y and H63D were not significantly different in NIDDM patients and controls. C282Y was observed in 0.59% of patients and 1.41% of controls. H63D was observed in 2.99% of patients and 3.08% of controls. All of the NIDDM patients who possessed either C282Y or H63D mutations had normal values of serum ferritin, serum iron and transferrin saturation. A woman who inherited C282Y also possessed HLA-A3, -B7 which is considered part of the ancestral haplotype containing the gene predisposing to hemochromatosis in Caucasians. The frequencies of C282Y and H63D vary in African Americans from different geographic regions of the United States; this variance can be explained by Caucasian admixture. Although most iron overload cases in African Americans bear more resemblance to cases of African iron overload than to those of Caucasian hemochromatosis, rare cases resembling Caucasian hemochromatosis have been observed in African Americans.

A rapid PCR-SSP assay for the hemochromatosis-associated Tyr250Stop mutation in the TFR2 gene

Several genes associated with hemochromatosis and primary iron overload have been identified. Mutations in the HFE gene have been detected in 60-100% of hemochromatosis patients of northern, central, and western European descent, although the frequencies of these mutations vary among racial and ethnic groups. Recently, a mutation in the gene encoding transferrin receptor-2 (exon 6, nucleotide 750 C --> G; Y250X) was detected by a PCR-restriction fragment length polymorphism (RFLP) method in Sicilians with hemochromatosis. We describe a modification of the original assay in which the sequence-specific priming PCR assay does not require the use of restriction endonuclease. The modified assay is robust and cost-efficient, and may be more useful for large-scale population studies because it can be performed rapidly on DNA extracted from buccal swabs.

Transferrin receptor-2 (TFR2) mutation Y250X in Alabama Caucasian and African American subjects with and without primary iron overload

Most cases of hemochromatosis are associated with mutations of the HFE gene on Ch6p. In southern Italy and central Alabama, the percentages of patients with hemochromatosis who have "atypical" HFE genotypes (defined as lack of C282Y homozygosity, C282Y/H63D compound heterozygosity, or H63D homozygosity) are relatively great. A mutation of the transferrin receptor-2 gene (TFR2; exon 6, nt 750 C --> G, replaces TAC with stop signal TAG; Y250X) on Ch7q22 was recently identified in two Sicilian families with HFE mutation-negative hemochromatosis. We wanted to estimate the frequency of this mutation in persons from central Alabama. We evaluated Caucasian hemochromatosis probands with atypical HFE genotypes and African Americans with primary iron overload. We also studied control Caucasians, including persons of southern Italian/Sicilian heritage, and control African Americans. Analysis of genomic DNA was performed using a PCR-sequence-specific priming assay and positive control specimens from Sicilian hemochromatosis subjects heterozygous and homozygous for Y250X. Among Alabama subjects, this allele was not detected in 113 Caucasians, including 21 hemochromatosis probands with atypical HFE genotypes and 92 normal control subjects (including 27 of southern Italian/Sicilian descent). In African Americans, Y250X was not detected in 20 index cases with primary iron overload or in 274 unrelated control subjects. We conclude that Y250X is uncommon in Caucasians with hemochromatosis associated with atypical HFE genotypes, in African Americans with primary iron overload, and in the general Caucasian and African American population subgroups in central Alabama.

Measurement of the rate of nu(e) + d --> p + p + e(-) interactions produced by (8)B solar neutrinos at the Sudbury Neutrino Observatory

Solar neutrinos from (8)B decay have been detected at the Sudbury Neutrino Observatory via the charged current (CC) reaction on deuterium and the elastic scattering (ES) of electrons. The flux of nu(e)'s is measured by the CC reaction rate to be straight phi(CC)(nu(e)) = 1.75 +/- 0.07(stat)(+0.12)(-0.11)(syst) +/- 0.05(theor) x 10(6) cm(-2) s(-1). Comparison of straight phi(CC)(nu(e)) to the Super-Kamiokande Collaboration's precision value of the flux inferred from the ES reaction yields a 3.3 sigma difference, assuming the systematic uncertainties are normally distributed, providing evidence of an active non- nu(e) component in the solar flux. The total flux of active 8B neutrinos is determined to be 5.44+/-0.99 x 10(6) cm(-2) s(-1).

Inheritance of two HFE mutations in African Americans: cases with hemochromatosis phenotypes and estimates of hemochromatosis phenotype frequency

PURPOSE

Two unrelated African Americans had hemochromatosis phenotypes and genotypes. We sought to identify origins of their HFE mutations and estimate frequencies of similar cases.

METHODS

HFE and HLA genotyping were performed in index cases and family members. HFE genotypes of 1,373 African American controls in five regions were tabulated.

RESULTS

Index cases had C282Y/C282Y and C282Y/H63D, respectively; each corresponding Ch6p was likely of Caucasian origin. In controls, frequencies of hemochromatosis-associated genotypes were as follows: C282Y/C282Y, 0.00011; C282Y/H63D, 0.00067; and H63D/H63D, 0.00101.

CONCLUSIONS

Penetrance-adjusted estimates indicate that approximately 9 African Americans per 100,000 have a hemochromatosis phenotype and two common HFE mutations. Hemochromatosis-associated genotype frequencies varied 11.7-fold across regions.

Screening for hemochromatosis in routine medical care: an evaluation of mean corpuscular volume and mean corpuscular hemoglobin

Our aim was to evaluate the potential utility of mean corpuscular volume (MCV) and mean corpuscular hemoglobin (MCH) to detect hemochromatosis. We computed the accuracy of MCV and MCH cut-off points > or = upper reference limits using data from 94 probands and 132 white controls. Our reference ranges are MCV 80.0-97.0 fL and MCH 26.0-32.0 pg. Sensitivity of MCV was 8.6-48.3% for men and 2.8-44.4% for women (cut-off points > or = 105.0 - > or = 97.0 fL, respectively). Sensitivity of MCH was 33.9-70.7% for men and 19.6-50.0% for women (cut-off points > or = 34.0 - > or = 32.0 pg, respectively). Using MCV and a hemochromatosis frequency typical of many western Caucasian populations (0.005), positive predictive values (PV+) were 2.1-100.0% in men and 4.2-100.0% in women. Using MCH, PV+ were 1.7-8.2% in men and 1.8-6.8% in women. We also calculated PV+ using the hemochromatosis frequency 0.015, which could occur in persons receiving medical care. Using MCV cut-off points > or = 101.0 fL, PV+ were 8.9-100.0% in men and 100.0% in women with maximum sensitivities of 24.1% and 25.0%, respectively. Using MCH testing, PV+ was 21.5% in men (cut-off point > or = 34.0 pg) and 18.2% in women (cut-off point > or = 33.0 pg) with sensitivities of 33.9% and 37.0%, respectively. Using MCV or MCH, sensitivity and PV+ for the HFE genotype C282Y/C282Y were generally greater than for "nonclassical" HFE genotypes. All negative predictive values in our study were > or = 98.5%. We conclude that supranormal values of MCV or MCH could be used to detect hemochromatosis in white persons of western European descent who are receiving routine medical care. Comparisons of MCV, MCH, and transferrin saturation testing and other implications of MCV and MCH testing for hemochromatosis in medical care are discussed.

Transferrin saturation phenotype and HFE genotype screening for hemochromatosis and primary iron overload: predictions from a model based on national, racial, and ethnic group composition in central Alabama

There is interest in general population screening for hemochromatosis and other primary iron overload disorders, although not all persons are at equal risk. We developed a model to estimate the numbers of persons in national, racial, or ethnic population subgroups in Jefferson County, Alabama, who would be detected using transferrin saturation (phenotype) or HFE mutation analysis (genotype) screening. Approximately 62% are Caucasians, 37% are African Americans, and the remainder are Hispanics, Asians, or Native Americans. The predicted phenotype frequencies are greatest in a Caucasian subgroup, ethnicity unspecified, which consists predominantly of persons of Scotch and Irish descent (0.0065 men, 0.0046 women), and in African Americans (0.0089 men, 0.0085 women). Frequencies of the HFE genotype C282Y/C282Y > or = 0.0001 are predicted to occur only among Caucasians; the greatest frequency (0.0080) was predicted to occur in the ethnicity-unspecified Caucasian population. C282Y/C282Y frequency estimates were lower in Italian, Greek, and Jewish subgroups. There is excellent agreement in the numbers of the ethnicity-unspecified Caucasians who would be detected using phenotype and genotype criteria. Our model also indicates that phenotyping would identify more persons with primary iron overload than would genotyping in our Italian Caucasian, Hispanic, and African American subgroups. This is consistent with previous observations that indicate that primary iron overload disorders in persons of southern Italian descent and African Americans are largely attributable to non-HFE alleles. Because the proportions of population subgroups and their genetic constitution may differ significantly in other geographic regions, we suggest that models similar to the present one be constructed to predict optimal screening strategies for primary iron overload disorders.

Severity of iron overload in hemochromatosis: effect of volunteer blood donation before diagnosis

BACKGROUND

An effort was made to determine if volunteer blood donation before diagnosis decreases the severity of iron overload at diagnosis in persons with hemochromatosis.

STUDY DESIGN AND METHODS

A study was performed in 1089 persons in the United States with hemochromatosis who responded to a convenience sample survey and in 124 C282Y/C282Y hemochromatosis probands diagnosed during routine medical care.

RESULTS

Less than half of questionnaire respondents (46.2%) and probands (35.5%) reported that they had been volunteer blood donors; 5.4 percent and 4.0 percent, respectively, had donated >20 units of blood. In either subject group, there were no significant differences according to age in the mean numbers of units that needed to be removed by therapeutic phlebotomy to induce iron depletion in subgroups of men and women, respectively. Similarly, there was no significant correlation of units of voluntary blood donation or of therapeutic phlebotomy index (= therapeutic phlebotomy units/age in years) with the number of therapeutic phlebotomy units needed to induce iron depletion. When questionnaire respondents were stratified by sex, there was no significant correlation of units of blood donation with the number of therapeutic phlebotomy units needed to induce iron depletion or with the therapeutic phlebotomy index.

CONCLUSION

Routine blood donation does not, on average, decrease the severity of iron overload in persons with hemochromatosis. These findings have implications for the understanding of the severity of iron overload and its complications in hemochromatosis, for advising persons with hemochromatosis about treatment, and for considering persons with hemochromatosis as possible blood donors.

Iron deficiency due to excessive therapeutic phlebotomy in hemochromatosis

Thirteen adults (eight men, five women) with hemochromatosis had undergone routine iron depletion therapy but while on maintenance phlebotomies developed iron deficiency which persisted for 25 +/- 13 (mean +/- 1 SD) months before diagnosis. All had symptoms and signs of iron deficiency. Levels of transferrin saturation were 10% +/- 5% (1 SD), and serum ferritin concentrations were 8 +/- 3 ng/mL. Eleven had anemia; eight had hypochromia and microcytosis. Bone marrow specimens obtained in five patients revealed no stainable iron. Medical records indicated that parameters of body iron status were infrequently or incorrectly used for adjusting the frequency of phlebotomies. Two patients developed iron deficiency due to additional blood loss from esophageal varices and bilateral hip replacement, respectively. Ten of the patients were treated with ferrous sulfate, 325 mg daily, for 2-6 weeks when anemia was corrected. In patients who were not given iron, anemia and microcytosis recovered in 8-24 months. We conclude that (i) sustained iron deficiency in hemochromatosis patients should be prevented by monitoring hemoglobin levels and serum ferritin; and (ii) hemoglobin concentrations and values of mean corpuscular hemoglobin may be higher in iron-deficient persons with hemochromatosis than in individuals without hemochromatosis. Symptomatic iron deficiency in hemochromatosis patients may be treated safely with a brief course of ferrous sulfate. Recovery is slower when iron is not given. However, iron supplementation is unnecessary and not recommended for the mild, self-limited anemia and decreased serum iron and ferritin concentrations encountered after initial iron depletion therapy for hemochromatosis.

Abnormalities of flavin monooxygenase as an etiology for sideroblastic anemia

We postulated that a deficiency of flavin monooxygenase (FMO)-a ferrireductase component of cells-could produce sideroblastic anemia. FMO is an intracellular ferrireductase which may be responsible for the obligatory reduction of ferric to ferrous iron so that reduced iron can be incorporated into heme by ferrochelatase. Abnormalities of this mechanism could result in accumulation of excess ferric iron in mitochondria of erythroid cells to produce ringed sideroblasts and impair hemoglobin synthesis. To investigate this hypothesis we obtained blood from patients with sideroblastic anemia and normal subjects. Extracts of peripheral blood lymphocytes were used to measure ferrireduction by utilization of NADPH. Lymphoid precursors are reported to accumulate iron in mitochondria similarly to erythroid precursors. Utilization of lymphoid precursors avoided the need for bone marrow aspirations. We studied three patients with sideroblastic anemia. One patient and his asymptomatic daughter had a significant decrease in ferrireductase activity. They also had markedly diminished concentrations of FMO in lymphocyte protein extracts on Western blots. This was accompanied by increased concentration of mobilferrin in the extracts. These results suggest that abnormalities of FMO and mobilferrin may cause sideroblastic anemia and erythropoietic hemochromatosis in some patients.

Intravenous iron dextran therapy in patients with iron deficiency and normal renal function who failed to respond to or did not tolerate oral iron supplementation

PURPOSE

To evaluate the safety and effectiveness of using 500-mg doses of iron as intravenous iron dextran after premedication with diphenhydramine, cimetidine, and dexamethasone.

SUBJECTS AND METHODS

We treated 135 iron-deficient adults (26 men, 109 women) with normal renal function (serum creatinine level </=1.5 mg/dL or blood urea nitrogen level </=26 mg/dL) who could not be treated adequately with oral iron supplements due to gastrointestinal symptoms (59%), inadequate hematologic response (39%), severe anemia (19%), or noncompliance (4%). Some patients had more than one reason for treatment. Resolution of iron deficiency was defined as the restoration of transferrin saturation, serum ferritin level, anemia, and abnormal erythrocyte indexes to normal or baseline values.

RESULTS

Before treatment with iron dextran, patients had a mean (+/- SD) transferrin saturation of 8% +/- 5%, a median serum ferritin level of 11 ng/mL, and a mean hemoglobin level of 10 +/- 2 g/dL. Ninety-two percent were anemic; 60% had unrecognized or untreated causes of anemia other than iron deficiency. We administered 285 iron dextran infusions (median 2, mean 2 infusions per patient; range 1 to 7). Eighty-seven percent of patients had no adverse reaction; 13% had mild reactions, especially arthralgias and myalgias. No patient had an anaphylaxis-like reaction. Fifty-four (40%) patients had resolution of iron deficiency, 34 (25%) continue to receive therapy, 36 (27%) returned to the care of their primary physician, and 11 (8%) died before iron repletion could be achieved.

CONCLUSIONS

Iron-deficient adults with normal renal function who cannot be treated adequately with oral iron supplements can be treated effectively and safely with this intravenous iron dextran regimen.

Transfusion iron overload in adults with acute leukemia: manifestations and therapy

BACKGROUND

Hepatic dysfunction occurs commonly among persons successfully treated for acute leukemia, and iron overload is a possible cause of hepatic and other abnormalities in these patients.

METHODS

We identified 5 adults 40+/-13 (mean +/- S.D.) years of age who developed transfusion iron overload in association with successful chemotherapy of de novo acute leukemia. None had evidence of hemochromatosis, viral hepatitis, or other primary hepatic disorders.

RESULTS

The mean serum ferritin concentration of our patients was 1531+/-572 ng/mL. Other abnormalities associated with transfusion iron overload were increased stainable iron in bone marrow macrophages, elevated serum concentrations of hepatic enzymes, hyperpigmentation, hyperferremia, elevated iron saturation of serum transferrin, and increased stainable iron in Kupffer cells and hepatocytes. Rheumatologic, endocrinologic, or cardiac abnormalities attributable to iron overload were not observed. Therapeutic phlebotomy was initiated after chemotherapy; recovery of hemoglobin concentrations after phlebotomy permitted weekly treatment in each case. This yielded an average of 28+/-9 units per patient (range 15-35 units). Abnormalities associated with transfusion iron overload resolved after iron depletion therapy. The mean leukemia-free survival of our patients is 96+/-36 months (range 40-125 months).

CONCLUSIONS

Our data and those of others suggest that 15 to 20% of adults who are long-term survivors of acute leukemia develop iron overload, often with hepatic abnormalities. Iron overload is a relatively common sequela to successful management of acute leukemia in adults for which routine evaluation should be performed and for which therapeutic phlebotomy should be used as treatment.

Population screening for hemochromatosis: has the time finally come?

Hemochromatosis refers to a group of common heritable disorders among Western Caucasians which increase susceptibility for development of iron overload and its complications. These consequences are preventable by early detection and simple, relatively inexpensive treatment. Screening of appropriate populations to detect hemochromatosis before iron overload occurs is both effective and cost-effective. The primary goal of screening should be the ongoing detection of persons with hemochromatosis, especially healthy individuals whose risk to develop iron overload is great, in a context that provides appropriate preventive treatment, education, and counseling. Although related issues warrant further study, implementation of well-designed screening programs for hemochromatosis should not be delayed.

Peripheral blood erythrocyte parameters in hemochromatosis: evidence for increased erythrocyte hemoglobin content

We studied peripheral blood erythrocyte parameters and HFE genotypes in 94 hemochromatosis probands and 132 white, normal control subjects. Mean red blood cell counts in probands and control subjects were not significantly different. However, mean values of hemoglobin, hematocrit, mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and mean corpuscular hemoglobin concentration (MCHC) were significantly higher in C282Y/C282Y probands (n = 60) than in wild-type control subjects (n = 65). Probands with other HFE genotypes also had increased mean erythrocyte parameters (other than red blood cell count). Peripheral blood smears prepared before therapeutic phlebotomy revealed that erythrocytes in many probands had increased diameters and were well filled with hemoglobin. Erythrocyte parameters were similar in C282Y/C282Y probands with and without hepatomegaly, elevated serum concentrations of hepatic enzymes, hepatic cirrhosis, diabetes mellitus, arthropathy, or hypogonadism. Among C282Y/C282Y probands, significantly greater values of MCV (but not other erythrocyte parameters) occurred among those who had transferrin saturation values of 75% or greater or iron overload at diagnosis. After iron depletion, the mean MCV, MCH, and MCHC values of C282Y/C282Y probands decreased but remained significantly greater than values in wild-type control subjects. Mean values of prephlebotomy MCH and MCHC concentrations were lower in HLA-A3-positive than in HLA-A3-negative C282Y/C282Y probands. We conclude that increased values of mean hemoglobin, hematocrit, MCV, MCH, and MCHC in hemochromatosis probands are caused primarily by increased iron uptake and hemoglobin synthesis by immature erythroid cells. Mechanisms of iron uptake by erythrocytes that could explain these results are discussed.

Hemochromatosis probands as blood donors

BACKGROUND

There has been no estimate of the potential eligibility of hemochromatosis probands or patients as blood donors or the suitability for transfusion of their blood that was removed by therapeutic phlebotomy.

STUDY DESIGN AND METHODS

According to guidelines of the American Association of Blood Banks, a retrospective estimate of these factors in 211 adult white hemochromatosis probands diagnosed during routine medical care was performed. The findings were compared to those in volunteer white whole-blood donors.

RESULTS

Before diagnosis of hemochromatosis, 49 probands had voluntarily donated 597 units of blood; 88 percent were donated by men. After diagnosis, 142 (67%) of 211 probands were potentially eligible. Data on each unit removed during iron-depletion therapy and during the first year of maintenance therapy (therapeutic phlebotomy) were available in 86 eligible probands. Of 1592 units, 1029 (65%) obtained during iron-depletion therapy in eligible probands were potentially suitable; 86 percent were from men. During maintenance therapy, 106 (88%) of 121 units from eligible probands were potentially suitable. In volunteer donors, 255,567 (94%) of 273,302 presenting donors were accepted. After testing and laboratory losses, 239,300 (94%) units were acceptable for transfusion.

CONCLUSIONS

In comparison with normal volunteers, hemochromatosis probands at diagnosis are less likely to be eligible as blood donors. The percentage of units obtained from patients during iron-depletion therapy that are suitable for transfusion is also lower, although the percentage increases during maintenance therapy.

Two novel missense mutations of the HFE gene (I105T and G93R) and identification of the S65C mutation in Alabama hemochromatosis probands

Sequencing of HFE exons 2, 3, 4, and 5, and of portions of introns 2, 4, and 5 revealed novel mutations in four of twenty hemochromatosis probands who lacked C282Y homozygosity, C282Y/H63D compound heterozygosity, or H63D homozygosity. Probands 1 and 2 were heterozygous for previously undescribed mutations: exon 2, nt 314T-->C (314C; I105T), and exon 2, nt 277G-->(277C; G93R), respectively; these probands were also heterozygous for H63D and C282Y, respectively. Probands 3 and 4 were heterozygous for a previously described but uncommon HFE mutation: exon 2, nt 193A-->T (193T; S65C). Proband 3 was also heterozygous for C282Y and had porphyria cutanea tarda, and Proband 4 had hereditary stomatocytosis. Each of these four probands had iron overload. In each proband with an uncommon HFE coding region mutation, I105T, G93R, and S65C occurred on separate chromosomes from those with the C282Y or H63D mutations. Neither I105T, G93R, nor S65C occurred as spontaneous mutations in our probands. The I105T and G93R mutations were linked to haplotypes bearing HLA-A3,-B7 and HLA-A2,-B62, respectively. The S65C mutation was linked to a haplotype characterized by HLA-32. Sixteen other probands did not have an uncommon HFE exon mutation. In 176 normal control subjects, two were heterozygous for S65C, but I105T and G93R were not detected. Nine of twenty probands were heterozygous and two probands were homozygous for a previously described base-pair change at intron 2, nt 3671T-->C. One proband without a detectable missense mutation had a previously described intron 5 allele (nt 6700G-->A). Heterozygosity for a previously described base-pair change in intron 4 (nt 5636T-->C) was detected in all persons we studied who also had the S65C mutation. One proband was heterozygous for a previously undescribed base-pair change at intron 5 (nt 5807A-->G). We conclude that uncommon HFE exon and intron mutations may be discovered among hemochromatosis patients who have "atypical" HFE genotypes.

Nongenital dermatologic disease in HIV-infected women

BACKGROUND

Dermatologic disease in HIV-infected women has not been adequately characterized.

OBJECTIVE

The main purposes of this study were to characterize nongenital dermatologic disease in HIV-infected women and correlate these diagnoses with CD4 lymphocyte count to compare these findings with those in published reports of men.

METHODS

This study was a retrospective chart review of female patients with dermatologic diagnoses followed up at an HIV clinic in New York City, seen by either a dermatologist (49 patients) and/or a primary care practitioner (114 patients). CD4 lymphocyte count was recorded if available within 6 months of diagnosis; mean CD4 count was calculated for all disorders with 5 or more diagnoses.

RESULTS

Oropharyngeal candidiasis, drug eruption, dermatophytosis, rash (not otherwise specified), nongenital herpes simplex, herpes zoster, and seborrheic dermatitis were the most prevalent diagnoses made by primary care providers. Itchy red bump disease, acne, atopic dermatitis, xerosis, seborrheic dermatitis, nongenital warts, and molluscum contagiosum were the most prevalent diagnoses made by the dermatologist. Mean CD4 lymphocyte count was lowest in itchy red bump disease, nongenital warts, nongenital herpes simplex, xerosis, and drug eruptions.

CONCLUSION

There appears to be no appreciable difference in the spectrum or prevalence of dermatologic disease in HIV-infected women versus HIV-infected men, except for a lower prevalence of Kaposi's sarcoma, oral hairy leukoplakia, and possibly onychomycosis in women. The degree of immunosuppression associated with various dermatoses in HIV-infected women is similar to that in men, except perhaps for molluscum contagiosum, which may appear earlier in women.

A survey of phlebotomy among persons with hemochromatosis

BACKGROUND

One in 10 whites in the United States is a carrier for hemochromatosis and an estimated 1 in 200 is clinically affected. Early treatment with therapeutic phlebotomy to remove excess iron can prevent associated chronic diseases. However, little information is available on the amount of blood withdrawn or the rates of withdrawal from hemochromatosis patients. The patterns of therapeutic phlebotomy and the magnitude of charges in persons with hemochromatosis were surveyed.

STUDY DESIGN AND METHODS

Surveys were mailed to persons with hemochromatosis identified by health care providers, blood centers, patient advocacy groups, and the Internet. There were 2362 respondents to the survey from the United States.

RESULTS

Thirty-seven percent of respondents reported being voluntary blood donors prior to diagnosis. The mean rate of therapeutic phlebotomy for iron depletion was 2.6 units per month (mean duration, 13 months). The mean rate of maintenance phlebotomy was 0.5 units per month. Therapeutic phlebotomy rates varied by sex, age, reason for diagnosis, and severity of symptoms. Seventy-six percent of respondents reported full or partial insurance coverage of therapeutic phlebotomy charges. Seventy-six percent received therapeutic phlebotomy services in a hospital or physician's office and 30 percent in a blood center. Charges for therapeutic phlebotomy varied by site, with a mean cost of $90 in hospitals and $52 in blood centers. Fifty-four percent of respondents attempted to donate blood after their diagnosis but were excluded.

CONCLUSION

The amount of blood withdrawn from persons with hemochromatosis is substantial. The location where patients received phlebotomy services appears to be influenced by charges and time since diagnosis.

A survey of 2,851 patients with hemochromatosis: symptoms and response to treatment

PURPOSE

Hemochromatosis is a genetic disorder of iron absorption that affects 5 per 1,000 persons and is associated with reduced health and quality of life. We sought to determine the type and frequency of symptoms that patients experienced before the diagnosis and the treatments that they received.

METHODS

We mailed a questionnaire to 3,562 patients with hemochromatosis who were located using patient advocacy groups, physicians, blood centers, newsletters, and the Internet.

RESULTS

Of the 2,851 respondents, 99% were white and 62% were men. Circumstances that led to diagnosis of hemochromatosis included symptoms (35%), an abnormal laboratory test (45%), and diagnosis of a family member with hemochromatosis (20%). The mean (+/- SD) age of symptom onset was 41 +/- 14 years. Symptoms had been present for an average of 10 +/- 10 years before the diagnosis was made. Among the 58% of patients with symptoms, 65% had physician-diagnosed arthritis and 52% had liver disease. The most common and troublesome symptoms were extreme fatigue (46%), arthralgia (44%), and loss of libido (26%). Physician instructions to patients included treatment with phlebotomy (90%), testing family members (75%), and avoiding iron supplements (65%).

CONCLUSIONS

The diagnosis of hemochromatosis in most patients was delayed. Physician education is needed to increase the detection of patients with the disease and to improve its management.

Diagnosis of hemochromatosis in family members of probands: a comparison of phenotyping and HFE genotyping

PURPOSE

We wanted to compare phenotyping and HFE genotyping for diagnosis of hemochromatosis in 150 family members of 61 probands.

METHODS

Phenotypes were defined by persistent transferrin saturation elevation, iron overload, or both; genotypes were defined by HFE mutation analysis.

RESULTS

Twenty-five family members were C282Y homozygotes; 23 of these (92%) had a hemochromatosis phenotype. Twenty-three family members had HFE genotype C282Y/H63D; eight of these (35%) had a hemochromatosis phenotype. Six of 102 (6%) family members who inherited other HFE genotypes had a hemochromatosis phenotype.

CONCLUSION

Phenotyping and genotyping are complementary in diagnosing hemochromatosis among family members of probands.

Management of hemochromatosis. Hemochromatosis Management Working Group

The complications of iron overload in hemochromatosis can be avoided by early diagnosis and appropriate management. Therapeutic phlebotomy is used to remove excess iron and maintain low normal body iron stores, and it should be initiated in men with serum ferritin levels of 300 microg/L or more and in women with serum ferritin levels of 200 microg/L or more, regardless of the presence or absence of symptoms. Typically, therapeutic phlebotomy consists of 1) removal of 1 unit (450 to 500 mL) of blood weekly until the serum ferritin level is 10 to 20 microg/L and 2) maintenance of the serum ferritin level at 50 microg/L or less thereafter by periodic removal of blood. Hyperferritinemia attributable to iron overload is resolved by therapeutic phlebotomy. When applied before iron overload becomes severe, this treatment also prevents complications of iron overload, including hepatic cirrhosis, primary liver cancer, diabetes mellitus, hypogonadotrophic hypogonadism, joint disease, and cardiomyopathy. In patients with established iron overload disease, weakness, fatigue, increased hepatic enzyme concentrations, right upper quadrant pain, and hyperpigmentation are often substantially alleviated by therapeutic phlebotomy. Patients with liver disease, joint disease, diabetes mellitus and other endocrinopathic abnormalities, and cardiac abnormalities often require additional, specific management. Dietary management of hemochromatosis includes avoidance of medicinal iron, mineral supplements, excess vitamin C, and uncooked seafoods. This can reduce the rate of iron reaccumulation; reduce retention of nonferrous metals; and help reduce complications of liver disease, diabetes mellitus, and Vibrio infection. This comprehensive approach to the management of hemochromatosis can decrease the frequency and severity of iron overload, improve quality of life, and increase longevity.

Hereditary hemochromatosis: gene discovery and its implications for population-based screening

OBJECTIVE

To evaluate the role of genetic testing in screening for hereditary hemochromatosis to help guide clinicians, policymakers, and researchers.

PARTICIPANTS

An expert panel was convened on March 3, 1997, by the Centers for Disease Control and Prevention (CDC) and the National Human Genome Research Institute (NHGRI), with expertise in epidemiology, genetics, hepatology, iron overload disorders, molecular biology, public health, and the ethical, legal, and social implications surrounding the discovery and use of genetic information.

EVIDENCE

The group reviewed evidence regarding the clinical presentation, natural history, and genetics of hemochromatosis, including current data on the candidate gene for hemochromatosis (HFE) and on the ethical and health policy implications of genetic testing for this disorder.

CONSENSUS PROCESS

Consensus was achieved by group discussion confirmed by a voice vote. A draft of the consensus statement was prepared by a writing committee and subsequently reviewed and revised by all members of the expert group over a 1-year period.

CONCLUSIONS

Genetic testing is not recommended at this time in population-based screening for hereditary hemochromatosis, due to uncertainties about prevalence and penetrance of HFE mutations and the optimal care of asymptomatic people carrying HFE mutations. In addition, use of a genetic screening test raises concerns regarding possible stigmatization and discrimination. Tests for HFE mutations may play a role in confirming the diagnosis of hereditary hemochromatosis in persons with elevated serum iron measures, but even this use is limited by uncertainty about genotype-phenotype correlations. To address these questions, the expert group accorded high priority to population-based research to define the prevalence of HFE mutations, age and sex-related penetrance of different HFE genotypes, interactions between HFE genotypes and environmental modifiers, and psychosocial outcomes of genetic screening for hemochromatosis.

Diagnosis of hemochromatosis probands in a community hospital

PURPOSE

To evaluate factors that lead to the diagnosis of hemochromatosis probands in a community hospital, including education of physicians about hemochromatosis and iron overload, specialty of physicians, diagnostic indicators of hemochromatosis, and clinical manifestations of hemochromatosis probands.

PATIENTS AND METHODS

We conducted a hemochromatosis education program for health care personnel associated with a community hospital and the public during 1990 to 1994. Data on physicians who diagnosed probands, diagnostic indicators of hemochromatosis, and manifestations of hemochromatosis and associated illnesses were tabulated. Iron grades of all hospital liver biopsy specimens obtained from Caucasian subjects during 1990 to 1994 were also analyzed.

RESULTS

We identified 162 hemochromatosis probands; 66.7% were diagnosed by physicians who participated in our education program. Primary care and internal medicine subspecialty physicians diagnosed 66.7% and 29.6% of probands, respectively, based on elevated serum iron parameters and hepatic enzyme concentrations (51.9% and 36.4% of probands, respectively). Iron overload occurred in 90.7%, and was associated with clinical manifestations in most. Of 844 hospital liver biopsy specimens from Caucasians, 8.5% had increased iron grades; 4.6% represented hemochromatosis.

CONCLUSIONS

Physicians with current education readily diagnose hemochromatosis probands during routine health care delivery, but most probands identified in this manner have iron overload. Our results suggest that community physicians and hospitals could contribute substantially to hemochromatosis screening programs, permitting detection of more homozygotes before the development of iron overload.

Genetic and clinical description of hemochromatosis probands and heterozygotes: evidence that multiple genes linked to the major histocompatibility complex are responsible for hemochromatosis

We evaluated Alabama hemochromatosis probands (n = 74) and normal control subjects (n = 142) for expression of the hemochromatosis-associated mutations nt 845G-->A (845A; Cys282Tyr) and nt 187C-->G (His63Asp) in a gene linked to the major histocompatibility complex (MHC). We also tabulated parameters of iron metabolism and iron overload in probands and in obligate heterozygote family members of homozygous Cys282Tyr probands. Among probands, 59.4% were Cys282Tyr homozygotes and 20.3% were heterozygotes; 20.3% did not express this mutation. In normal control subjects, 14.7% were heterozygous for the Cys282Tyr mutation; one normal control subject was homozygous for the Cys282Tyr mutation. None (0 of 44) of our Cys282Tyr-homozygous hemochromatosis probands had the His63Asp mutation. Of the Cys282Tyr-heterozygous and -negative probands, the His63Asp mutation occurred in 26.7% (4/15) and 53.3% (8/15), respectively. In normal control subjects, 23.2% were heterozygous for the His63Asp mutation; 2.8% were homozygous. Induction phlebotomy requirements and other manifestations of iron overload were significantly greater in Cys282Tyr homozygotes than among other probands. Cys282Tyr-heterozygous probands had significantly higher values of serum iron parameters than did obligate Cys282Tyr heterozygotes whose values were, on the average, normal. Co-expression of HLA-A3, HLA-B7, and D6S105(8) was significantly more frequent in all subgroups of probands stratified by Cys282Tyr expression than in normal control subjects. These results demonstrate that the severity of iron overload in hemochromatosis is affected significantly by genetic factors. Further, our findings support the hypothesis that one or more MHC-linked genes other than that corresponding to the Cys282Tyr and His63Asp mutations contributes to increased iron absorption and iron overload in hemochromatosis probands.

Hemochromatosis: association of severity of iron overload with genetic markers

We postulated that the severity of iron overload in homozygous hemochromatosis probands is related to the expression of HLA-A3 or D6S105 allele 8. Therefore, we used these markers to characterize Alabama hemochromatosis probands and normal control subjects. We then quantified the blood removed by phlebotomy to exhaust body iron stores and maintain normal serum ferritin concentrations in our hemochromatosis probands. Induction and maintenance phlebotomy requirements were significantly greater in presumed HLA-A3 homozygotes or in D6S105 allele 8 homozygotes than in homozygous probands lacking these markers. Intermediate values were observed in probands who were HLA-A3 or allele 8 heterozygotes, respectively. We also analyzed data from males and females separately. Among subjects of the same sex, the induction and maintenance phlebotomy requirements in subjects presumed to be HLA-A3 homozygotes or in allele 8 homozygotes were greater than those of other groups. Our results support the hypothesis that the severity of iron overload in hemochromatosis is determined predominantly by genetic factors, and provide evidence that two or more mutations for hemochromatosis exist. However, the design of our study does not permit a distinction to be made between allelic and locus heterogeneity for the hemochromatosis gene(s).