To the Editor, Several hemoglobin (Hb) variants have been reported in Turkish population [1–3]. Herein, we represent a nucleotide alteration of the alpha-2 chain variant, Hemoglobin Fontainebleau (a21(B2) Ala-Pro) in an 8year-old male Turkish child living in Ankara, Turkey. He was admitted to the Hospital Pediatrics Department for routine check-up. His physical examination was normal, and there was no positive consanguinity between his parents. High red blood cell count and low mean corpuscular volume were detected in complete blood count (CBC) (Fig. 1a). High-performance liquid chromatography (HPLC) showed an asymmetry (shoulder formation) in the descending part of A0 and in the A2 curve. Levels of HbA, HbA2, and HbF were observed as 93.25%, 3.55%, and 1.07%, respectively (Fig. 1a). His mother and 6year-old sister were also screened. Their HPLC chromatograms showed similar pattern (Fig. 1b, c). Sequence analysis of HBA1 and HBA2 genes were performed by using MiSeq next-generation sequencing (NGS) platform (Illumina, San Diego, CA, USA). Genomic DNA was extracted by using the QIAamp DNA Blood Midi Kit (Qiagen, Hilden, Germany). All coding regions and exon-intron boundaries of the genes were amplified using PCR primers, designed with PRIMER©Primer Designer v.2.0 (Scientific & Educational Software programme) software. Alignment was done by using hg19 genome with MiSeq Reporter software (Illumina Inc.), and analysis was done with IGV 2.3 (Broad Institute) software. These genes were also tested for common deletions with MLPA (multiplex ligation-dependent probe amplification) method (SALSA MLPA P140 HBA probemix, MRC Holland, Amsterdam, Holland). NM_ 000558.5(HBA1):c.64G>C (p.Ala22Pro) was detected by sequence analysis while MLPA test was normal (Fig. 1a, b). Written informed consent for genetic analysis was obtained both from the child’s parents and from the mother. Hemoglobin Fontainebleau (a21(B2) Ala-Pro) is a rarely reported hemoglobin variant. It was first reported in an Italian family without DNA analysis in 1989 and later on in India, Canada, South Cyprus, United Arab Emirates, Iraq (family living in New Zealand), and Turkey. It was described as a silent mutation and was also reported in combination with heterozygote forms of sickle cell, hereditary spherocytosis, and Hb Punjab [1, 4–6]. It is interesting that the cases identified were on historical migration routes. Since Turkey is located at the intersection of two continents, it is not surprising that many different hemoglobin variants are observed. Further observation of Hb Fontainebleau (a21(B2) Ala-Pro) suggests that this variant is found sporadically in the Turkish population.

中文翻译：

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进一步观察土耳其家庭中的血红蛋白枫丹白露 (a21(B2) Ala-Pro)

致编辑，土耳其人群中已经报道了几种血红蛋白 (Hb) 变异体 [1-3]。在此，我们代表了一名居住在土耳其安卡拉的 8 岁土耳其男性儿童的 alpha-2 链变体血红蛋白枫丹白露 (a21(B2) Ala-Pro) 的核苷酸改变。他被送往医院儿科进行常规检查。体检正常，父母间无血缘关系。在全血细胞计数（CBC）中检测到高红细胞计数和低平均红细胞体积（图 1a）。高效液相色谱 (HPLC) 显示 A0 的下降部分和 A2 曲线不对称（形成肩峰）。观察到的 HbA、HbA2 和 HbF 水平分别为 93.25%、3.55% 和 1.07%（图 1a）。他的母亲和 6 岁的妹妹也接受了筛查。他们的 HPLC 色谱图显示出相似的模式（图 1b、c）。HBA1 和 HBA2 基因的序列分析通过使用 MiSeq 下一代测序 (NGS) 平台 (Illumina, San Diego, CA, USA) 进行。使用 QIAamp DNA Blood Midi Kit (Qiagen, Hilden, Germany) 提取基因组 DNA。使用PCR引物扩增基因的所有编码区和外显子-内含子边界，使用PRIMER©Primer Designer v.2.0（科学与教育软件程序）软件设计。通过使用 hg19 基因组与 MiSeq Reporter 软件（Illumina Inc.）进行比对，并使用 IGV 2.3（Broad Institute）软件进行分析。还使用 MLPA（多重连接依赖性探针扩增）方法（SALSA MLPA P140 HBA 探针混合物，MRC Holland，Amsterdam，Holland）测试了这些基因的常见缺失。NM_000558.5(HBA1):c.64G> C（p.Ala22Pro）通过序列分析检测到，而MLPA测试正常（图1a，b）。从孩子的父母和母亲那里获得了遗传分析的书面知情同意书。血红蛋白枫丹白露 (a21(B2) Ala-Pro) 是一种很少报道的血红蛋白变异体。1989 年在一个没有 DNA 分析的意大利家庭中首次报道了它，后来在印度、加拿大、南塞浦路斯、阿拉伯联合酋长国、伊拉克（居住在新西兰的家庭）和土耳其。它被描述为一种沉默突变，也被报道与杂合子形式的镰状细胞、遗传性球形红细胞增多症和旁遮普血红蛋白相结合 [1, 4-6]。有趣的是，发现的病例发生在历史迁徙路线上。由于土耳其位于两大洲的交汇处，因此观察到许多不同的血红蛋白变体也就不足为奇了。