台灣海洋性貧血產前篩檢之探討

Abstract

本研究旨在增加醫療人員對海洋性貧血的了解，並強調篩檢的重要性。台灣甲型和乙型海洋性貧血的帶因率高，現行篩檢方法雖可避免大部分重型海洋性貧血的出生，但忽略了隱性的海洋性貧血帶因者，仍可能導致中、重度海洋性貧血的情況。希望能透過詳細的文獻回顧和資訊分享，提供此疾病之深入理解和預防中、重度海洋性貧血患者出生的方法。 本研究採病歷回溯性研究方法，蒐集2019年4月1日到2022年8月30日於禾馨婦產科看診有使用帶因篩檢於產前檢測的孕婦且結果為檢驗出有海洋性貧血基因異常之個案，研究結果顯示於1901位有進行帶因篩檢的個案中共179位海洋性貧血帶因者，帶因率為9.4%，甲型海洋性貧血帶因率（Prevalence）為7.7%、乙型海洋性貧血帶因率1.3%、同時攜帶甲型與乙型海洋性貧血帶因率0.1%；以所有海洋性貧血帶因者來說，甲型佔比（Constituent ratio）84.5%、乙型佔13.8%、攜帶甲型與乙型佔1.1%，這帶因率及佔比較過往的研究高；而甲型海洋性貧血中東南亞缺失型帶因率佔所有甲型海洋性貧血的52.7%，其次是單一基因缺失的右端缺失型30.4%，這樣的比例較與過去文獻不相同，可能是因本研究是以帶因篩檢基因檢測結果去蒐集海洋性貧血帶因者；甲型與乙型海洋性貧血個案中分別有33.8%及12.5%的個案可能會在傳統篩檢步驟之下被遺漏，其中有可能造成非缺失型血紅素H疾病的Hb CS型帶因個案也有Hb E等基因型， Hb E在東南亞人口中是非常常見的變異型血紅素，當與0海洋性貧血帶因者配對時可能會產下輸血依賴型乙型海洋性貧血患者。 重度的甲型及乙型海洋性貧血，因公共健康政策執行成效良好，個案數目雖已逐年降低，但隱性帶因者所帶來的問題仍應注意及預防，而帶因篩檢能提供更多關於隱性海洋性貧血的訊息，對產前篩檢帶來幫助，在產前若能透過適當的檢測正確分辨胎兒的基因型，對於臨床醫療人員的診斷及準父母的生育決策都會有助益。

The aim of this study was to increase healthcare professionals' understanding of thalassemia and emphasize the importance of screening. The carrier rates of alpha-thalassemia and beta-thalassemia are high in Taiwan. Although current screening methods can prevent the birth of most severe cases of thalassemia, they overlook carriers with mild forms of the condition, which may still lead to the occurrence of moderate to severe thalassemia. Through a detailed literature review and information sharing, it is hoped to provide a deeper understanding of this disease and methods for preventing the birth of moderate-to-severe thalassemia patients. This study adopted a retrospective medical record review method and collected data from pregnant women who underwent carrier screening for thalassemia using prenatal testing at the Dianthus mfm clinic from April 1, 2019, to August 30, 2022. The results showed that out of 1901 cases that underwent carrier screening, there were a total of 179 carriers of thalassemia, resulting in a carrier rate of 9.4%. The prevalence of alpha-thalassemia carriers was 7.7%, beta-thalassemia carriers were 1.3%, and carriers with both alpha and beta-thalassemia were 0.1%. Among all thalassemia carriers, 84.5% had alpha-thalassemia, 13.8% had beta-thalassemia, and 1.1% had both types. These carrier rates and proportions were higher than in previous studies. Among carriers of alpha-thalassemia, the prevalence of the SEA (Southeast Asian) accounted for 52.7% of all cases, followed by the right-end deletion type (-3.7) at 30.4%. This differs from previous literature, possibly due to the collection of thalassemia carriers based on carrier screening genetic test results. In cases of alpha-thalassemia and beta-thalassemia, 33.8% and 12.5% of cases, respectively, may be missed in the traditional screening steps. Among them, cases with non-deletion-type hemoglobin H disease may have genotypes such as Hb CS and Hb E. Hb E is a common variant of hemoglobin in the Southeast Asian population, and when paired with 0-thalassemia carriers, it may result in transfusion-dependent beta-thalassemia patients. Severe forms of alpha-thalassemia and beta-thalassemia have shown a decline in the number of cases over the years due to the effective implementation of public health policies. However, attention and prevention should still be given to the issues caused by carriers of the mild forms of thalassemia. Carrier screening can provide additional information about latent thalassemia and assist in prenatal screening. It would be beneficial for clinical healthcare providers' diagnoses and prospective parents' reproductive decisions if appropriate testing could accurately determine the fetus's genotype during pregnancy.