Hereditary hemochromatosis: mutations in genes involved in iron homeostasis in Brazilian patients.

BACKGROUND: p.C282Y mutation and rare variants in the HFE gene have been associated with hereditary hemochromatosis (HH). HH is also caused by mutations in other genes, such as the hemojuvelin (HJV), hepcidin (HAMP), transferrin receptor 2 (TFR2) and ferroportin (SLC40A1). The low rate homozygous p.C282Y mutation in Brazil is suggestive that mutations in non-HFE genes may be linked to HH phenotype. AIM: To screen exon-by-exon DNA sequences of HFE, HJV, HAMP, TFR2 and SLC40A1 genes to characterize the molecular basis of HH in a sample of the Brazilian population. MATERIALS AND METHODS: Fifty-one patients with primary iron overload (transferrin saturation ≥50% in females and ≥60% in males) were selected. Subsequent bidirectional DNA sequencing of HFE, HJV, HAMP, TFR2 and SLC40A1 exons was performed. RESULTS: Thirty-seven (72.5%) out of the 51 patients presented at least one HFE mutation. The most frequent genotype associated with HH was the homozygous p.C282Y mutation (n=11, 21.6%). In addition, heterozygous HFE p.S65C mutation was found in combination with p.H63D in two patients and homozygous HFE p.H63D was found in two patients as well. Sequencing in the HJV and HAMP genes revealed HJV p.E302K, HJV p.A310G, HJV p.G320V and HAMP p.R59G alterations. Molecular and clinical diagnosis of juvenile hemochromatosis (homozygous form for the HJV p.G320V) was described for the first time in Brazil. Three TFR2 polymorphisms (p.A75V, p.A617A and p.R752H) and six SLC40A1 polymorphisms (rs13008848, rs11568351, rs11568345, rs11568344, rs2304704, rs11568346) and the novel mutation SLC40A1 p.G204S were also found. CONCLUSIONS: The HFE p.C282Y in homozygosity or in heterozygosity with p.H63D was the most frequent mutation associated with HH in this sample. The HJV p.E302K and HAMP p.R59G variants, and the novel SLC40A1 p.G204S mutation may also be linked to primary iron overload but their role in the pathophysiology of HH remain to be elucidated.

Relationship between the iron status of pregnant women and their newborns

OBJECTIVE: To determine the relationship between iron nutritional status of pregnant women and their newborns using a combination of hematological and biochemical parameters for the diagnosis of iron deficiency. METHODS: A cross-sectional study was conducted in Jundiaí, Southeastern Brazil, in 2000. Venous blood samples collected from 95 pregnant women and from their umbilical cord and used for the determination of complete blood count, serum iron, total iron-binding capacity, serum ferritin, zinc protoporphyrin, and transferrin saturation. Women were classified into three groups: anemic, iron deficient and non-iron deficient. Statistical analysis included the Tukey-HSD test, Pearson's correlation coefficient and multiple linear regression analysis. RESULTS: Among pregnant women, 19 percent were anemic (97.9 percent mildly anemic and 2.1 percent moderately anemic) and 30.5 percent were iron deficient. No significant difference was seen in mean values of any parameter studied between newborns in the three groups (p>0.05). Multiple linear regression analysis showed weak association between neonatal and maternal parameters. CONCLUSIONS: The iron nutritional status of pregnant women with iron deficiency or mild anemia does not seem to have a significant impact on the iron levels of their children.

OBJETIVO: Determinar a relação entre os níveis de ferro de gestantes e seus filhos recém-nascidos, utilizando uma combinação de parâmetros hematológicos e bioquímicos para o diagnóstico da deficiência de ferro. MÉTODOS: Estudo transversal realizado em Jundiaí, SP, em 2000. Amostras de sangue venoso foram coletadas de 95 gestantes e do cordão umbilical de cada uma, e utilizadas na determinação de hemograma completo, ferro sérico, capacidade total de ligação do ferro, ferritina sérica, zinco-protoporfirina, e saturação de transferrina. As mulheres foram classificadas em três grupos: anêmicas, deficientes de ferro e não-deficientes de ferro. As análises estatísticas utilizadas foram o teste de Tukey-HSD, o coeficiente de correlação de Pearson e regressão linear múltipla. RESULTADOS: Entre as gestantes, 19 por cento estavam anêmicas (97,9 por cento levemente anêmicas e 2,1 por cento moderadamente anêmicas) e 30,5 por cento apresentavam deficiência de ferro. Não foi observada diferença significativa nas médias dos valores dos parâmetros estudados nos recém-nascidos dos três grupos (p>0,05). A análise de regressão linear múltipla mostrou fraca associação entre os parâmetros maternos e neonatais. CONCLUSÕES: Os níveis de ferro de gestantes com deficiência de ferro ou com anemia leve/moderada parecem não influenciar de forma significativa os níveis de ferro de seus filhos.

Relationship between the iron status of pregnant women and their newborns.

OBJECTIVE: To determine the relationship between iron nutritional status of pregnant women and their newborns using a combination of hematological and biochemical parameters for the diagnosis of iron deficiency. METHODS: A cross-sectional study was conducted in Jundiaí, Southeastern Brazil, in 2000. Venous blood samples collected from 95 pregnant women and from their umbilical cord and used for the determination of complete blood count, serum iron, total iron-binding capacity, serum ferritin, zinc protoporphyrin, and transferrin saturation. Women were classified into three groups: anemic, iron deficient and non-iron deficient. Statistical analysis included the Tukey-HSD test, Pearson's correlation coefficient and multiple linear regression analysis. RESULTS: Among pregnant women, 19% were anemic (97.9% mildly anemic and 2.1% moderately anemic) and 30.5% were iron deficient. No significant difference was seen in mean values of any parameter studied between newborns in the three groups (p>0.05). Multiple linear regression analysis showed weak association between neonatal and maternal parameters. CONCLUSIONS: The iron nutritional status of pregnant women with iron deficiency or mild anemia does not seem to have a significant impact on the iron levels of their children.

Elevated serum S-adenosylhomocysteine in cobalamin-deficient megaloblastic anemia.

Impaired methylation due to accumulation of S-adenosylhomocysteine (SAH) may contribute to the pathophysiology of cobalamin-deficient anemia. We assayed serum S-adenosylmethionine (SAM), SAH, total homocysteine (tHcy), and methylmalonic acid (MMA) in 15 subjects with cobalamin-deficient megaloblastic anemia and compared results with those of 19 subjects with anemia/pancytopenia due to other causes. Cobalamin-deficient subjects had a median hematocrit level of 20% and mean cell volume of 111.7 fL. The median serum cobalamin level was 37 pg/mL, MMA 3030 nmol/L, and tHcy 62.0 micromol/L. SAH was elevated in 13 of 15 subjects (median, 42 nmol/L) and the median SAM value was normal (103 nmol/L), but SAM/SAH ratio was low (2.5). The SAH was higher and SAM/SAH ratio was lower in cobalamin-deficient subjects compared with those with other anemias after excluding 4 patients with renal insufficiency. SAM concentrations were not low in cobalamin deficiency. Cobalamin injections corrected anemia, MMA, tHcy, SAM/SAH ratio, and SAH. Some hematologic variables were inversely correlated with SAH and cobalamin but not tHcy or MMA. In conclusion, serum SAH is elevated in cobalamin-deficient subjects with megaloblastic anemia and corrects with parenteral cobalamin therapy.

Low ratio of S-adenosylmethionine to S-adenosylhomocysteine is associated with vitamin deficiency in Brazilian pregnant women and newborns.

BACKGROUND: Pregnant women with low cobalamin concentrations are unable to provide the necessary amount of cobalamin to their fetuses. The effect of low maternal cobalamin concentrations on transmethylation metabolism in pregnant women and their newborns is unknown. OBJECTIVE: We investigated the relation between maternal and neonatal cobalamin concentrations and changes in total homocysteine (tHcy), S-adenosylmethionine (SAM), and S-adenosylhomocysteine (SAH). DESIGN: Hematologic data and concentrations of cobalamin, red blood cell folate, serum folate, tHcy, methylmalonic acid, SAM, SAH, and other metabolites were measured in 119 serum specimens from pregnant Brazilian women (gestational age: 37-42 wk) and their newborns' placental veins at the time of delivery. RESULTS: The tHcy concentrations were higher in placental vein serum from newborns whose mothers had low cobalamin. Serum SAH concentrations were elevated and serum SAM and methionine concentrations were decreased in pregnant women with lower cobalamin concentrations. SAM:SAH was significantly decreased in both cobalamin-deficient pregnant women and their newborns. CONCLUSIONS: Lower maternal cobalamin concentrations are associated with higher tHcy and lower SAM:SAH in newborns. Because SAM:SAH is closely linked with the activity of numerous enzymatic methylation reactions, these results suggest that methylation could be impaired in cobalamin-deficient pregnant women and their newborns.

Prevençäo de hemoglobinopatias a partir do estudo em gestantes / Hemoglobinopathies: a study in pregnancy

A populaçäo brasileira apresenta genes para as hemoglobinas anormais com freqüências variáveis e influenciadas por seus grupos raciais formadores. Portanto, detecçäo dos portadores destas alteraçöes genéticas é de importância para a saúde pública pois representam fonte de novos heterozigotos e de possíveis homozigotos. O controle das hemoglobinopatias tem sido possível por meio do aconselhamento genético e diagnóstico precoce. O acompanhamento clínico dos homozígotos, o esclarecimento dos heterozigotos e em especial dos casais de risco, pode contribuir para evitar o nascimento de crianças portadoras de uma patologia genética, muitas vezes letal. Por essas razöes o presente trabalho teve como objetivos: avaliar a importância da análise de gestantes para detecçäo de hemoglobinopatias com os propósitos de detectar a prevalência e efetuar a prevençäo, o estudo familial e a conscientizaçäo; para os casos positivos como casal de risco, orientar para o devido encaminhamento médico; avaliar a resposta do programa. Do total de 696 gestantes analisadas, 10,7 por cento apresentaram hemoglobinopatias com as seguintes prevalências: Talassemia alfa 6,75 por cento; Hb AS 2,01 por cento; Talassemia beta menor 1,29 por cento; Hb AC o,28 por cento; Hb Aj 0,14 por cento; Hb AS/Tal. alfa: 0,14 por cento; e P.H.H.F.0,14 por cento. A elevada prevalência de hemoglobinopatias encontrada na populaçäo de gestantes estudada, evidencia a necessidade da implantaçäo de exames para hemoglobinopatias na rotina de pré-natais, uma vez que neste período as mäes estäo mais propensas à se preocuparem com sua própria saúde e a de seu bebê e, quanto mais precoce forem diagnosticadas as alteraçöes das hemoglobinas, melhor e mais adequada será a orientaçäo dada ao casal.