[Association between genotype and clinical phenotype in children with primary hemophagocytic lymphohistiocytosis].

Abstract

Objective: To investigate the association between genotype and clinical phenotype in children with primary hemophagocytic lymphohistiocytosis (HLH). Methods: Clinical data of 38 children with primary HLH at Beijing Children s Hospital from November 2015 to October 2020 were analyzed retrospectively. According to whether destructive mutation site, familial HLH (FHL) or non-familial HLH, degranulation pathway and non-degranulation pathway were detected in them, these patients were divided into different groups. Clinical characteristics, laboratory tests and functional tests were analyzed in different groups. Wilcoxon test or chi-square test were used for comparison between groups. Results: Among 38 cases, there were 23 males and 15 females. The age of onset was 2.5 (0.1-13.7) years. PRF1 (13/38, 34%) and UNC13D (12/38, 32%) gene mutations had the highest detectable rate. Correlation analysis between genotypes and phenotypes suggested that patients in destructive mutation sites group (n=25) had a younger age of onset than that in non-destructive mutation sites group (n=13) (1.0 (0.1-9.0) vs. 4.0 (0.4-13.4) years, Z=-2.711, P=0.005). The incidence of central nervous system involvement and convulsion was higher in patients in familial HLH group (n=26) than that in non-familial HLH group (n=12)(62% (16/26) vs. 2/12, χ²=6.631, P=0.015; 54% (14/26) vs. 2/12, χ²=4.656, P=0.040). The levels of soluble CD25, bilirubin, interferon γ (IFN-γ) and interleukin 10 (IL-10) were higher in degranulation pathway impairment group than that in the non-degranulation pathway impairment group (38 444 (2 393-44 000) vs.15 304 (1 620-36 937) ng/L,Z=2.634,P=0.008; 23.5 (6.3-126.4) vs. 6.0 (3.6-31.0) μmol/L, Z=2.992, P=0.003; 20.7 (0-248.7) vs. 11.9 (2.6-21.0) ng/L, Z=2.156, P=0.031; 20.7 (4.3-2 500.0) vs. 11.8 (4.0-88.0) ng/L, Z=2.210, P=0.027). However, the levels of neutrophils, ferritin and lactate dehydrogenase (LDH) in degranulation pathway impairment group were lower in the non-degranulation pathway impairment group (0.5 (0.1-8.0)×109 vs. 1.0 (0.9-2.3)×109/L, Z=-3.197, P=0.001; 1 133 (78-10 452) vs. 3 048 (630-37 900) μg/L, Z=-2.407, P=0.016; 410 (188-1 254) vs. 599 (389-3 147) U/L, Z=-2.489, P=0.013). Conclusions: PRF1 and UNC13D gene mutations are most common in primary HLH. Patients with destructive gene mutations have a younger age of onset. Patients with familial HLH are more likely to have central nervous system involvement and convulsions. The levels of sCD25, bilirubin, IFN-γ and IL-10 are higher in the degranulation pathway patients.