Fu Chunyan, Wen Rong, Zhou Jiyong, Hu Jingfei, Liu Xiuxiang
Clin Lab. 2023 Dec 1;69(12). doi: 10.7754/Clin.Lab.2023.230648.
Familial hemophagocytic lymphohistiocytosis type 5 (FHL-5) is a rare hyper-inflammatory syndrome caused by mutations in STXBP2. Most cases present at 2 - 6 months of age, and FHL-5 is extremely rare in neonates.
Appropriate laboratory tests, abdominal ultrasonography and whole exome sequencing were carried out. Respiratory support, antibiotics, and transfusion of blood products were done.
Laboratory tests revealed metabolic acidosis, thrombocytopenia, mild anemia, and low fibrinogen level. Blood culture, metagenomics, and TORCH screening were negative. Liver and spleen enlargements were confirmed by abdominal ultrasonography. Whole exome sequencing identified a homozygous mutation in STXBP2 c. 1432del G (p. V478Sfs*5). The heterozygous STXBP2 mutation was identified in the paternal grandfather, maternal grandfather, and parents.
Here we report a case with a novel homozygous deletion in exon 16 of STXBP2, which caused the earliest reported case of FHL-5 in a neonate. Our results identify a new pathogenic variant for the early identification and clinical consultation of FHL-5.
5型家族性噬血细胞性淋巴组织细胞增生症（FHL-5）是一种由STXBP2基因突变引起的罕见的高炎症综合征。大多数病例在2至6个月龄时出现，FHL-5在新生儿中极为罕见。
进行了适当的实验室检查、腹部超声检查和全外显子组测序。给予呼吸支持、抗生素治疗及输血制品。
实验室检查显示代谢性酸中毒、血小板减少、轻度贫血和纤维蛋白原水平降低。血培养、宏基因组学和TORCH筛查均为阴性。腹部超声检查证实肝脏和脾脏肿大。全外显子组测序在STXBP2基因中鉴定出一个纯合突变，即c.1432del G（p.V478Sfs*5）。在患儿的祖父、外祖父和父母中鉴定出杂合的STXBP2突变。
我们报告了1例STXBP2基因第16外显子存在新型纯合缺失的病例，该病例为报道最早的新生儿FHL-5病例。我们的结果鉴定出一种新的致病变异，有助于FHL-5的早期诊断及临床会诊。
