Publicação
Hemoglobina fetal mutante : um caso clínico
| Resumo: | Introduction: Neonatal cyanosis may become an important and challenging diagnosis. There are several causes including respiratory or heart problems and infectious diseases. Although a rare condition, cyanosis can be related to methemoglobinemia. This syndrome may be obtained by exposure to several oxidizing agents but it can also be due to congenital defects, such as cytochrome-b5 reductase deficiency and Hemoglobin-M (Hb-M) variants. Case Presentation: It is detected in a newborn girl, who was apparently well until 40 hours after birth, an episode of hypoxemia after a screening for critical congenital heart disease. Following various pathologies exclusions, and under oxygen therapy with weak response, methemoglobinemia was suspected to be the cause, which leaded to the newborn’s transference to Hospital Santa Maria. During the period of hospitalization, the girl kept a stable clinical picture only presenting discreet greyish-color of the skin. After a normal hemoglobin electrophoresis, normal G6PD levels and slightly low cytochrome-b5 reductase assay, it comes the hemoglobin’s genetic sequencing, where it was identified a heterozygous mutation of the γ chain associated to the variant Hb F Viseu. Because it’s a γ chain related mutation, according to the fetal hemoglobin’s transition to the adult form, the values of methemoglobin decreased heading back to the standards parameters as expected. Conclusion: This is a rare cause of cyanosis with just a few cases described in the medical literature. The mutation was identified for the first time in 2012 and it fits in the sixth γ-chain variant already known. A few Hb-M variants are not detected by hemoglobin electrophoresis, therefore the diagnostic is achieved through genetic sequencing. |
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| Autores principais: | Nogueira, José Pedro Ferreira |
| Assunto: | Cianose neonatal Hemoglobina M Meta-hemoglobinémia |
| Ano: | 2014 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso restrito |
| Instituição associada: | Universidade de Lisboa |
| Idioma: | português |
| Origem: | Repositório da Universidade de Lisboa |
| Resumo: | Introduction: Neonatal cyanosis may become an important and challenging diagnosis. There are several causes including respiratory or heart problems and infectious diseases. Although a rare condition, cyanosis can be related to methemoglobinemia. This syndrome may be obtained by exposure to several oxidizing agents but it can also be due to congenital defects, such as cytochrome-b5 reductase deficiency and Hemoglobin-M (Hb-M) variants. Case Presentation: It is detected in a newborn girl, who was apparently well until 40 hours after birth, an episode of hypoxemia after a screening for critical congenital heart disease. Following various pathologies exclusions, and under oxygen therapy with weak response, methemoglobinemia was suspected to be the cause, which leaded to the newborn’s transference to Hospital Santa Maria. During the period of hospitalization, the girl kept a stable clinical picture only presenting discreet greyish-color of the skin. After a normal hemoglobin electrophoresis, normal G6PD levels and slightly low cytochrome-b5 reductase assay, it comes the hemoglobin’s genetic sequencing, where it was identified a heterozygous mutation of the γ chain associated to the variant Hb F Viseu. Because it’s a γ chain related mutation, according to the fetal hemoglobin’s transition to the adult form, the values of methemoglobin decreased heading back to the standards parameters as expected. Conclusion: This is a rare cause of cyanosis with just a few cases described in the medical literature. The mutation was identified for the first time in 2012 and it fits in the sixth γ-chain variant already known. A few Hb-M variants are not detected by hemoglobin electrophoresis, therefore the diagnostic is achieved through genetic sequencing. |
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