Crohn’s disease (CD) is a chronic idiopathic inflammatory bowel condition that can affect any part of the gastrointestinal tract. Several hundred candidate loci or genes including PTPN2 have been reportedly associated with CD. A whole-exome sequencing (WES) was conducted in a 9-year-old Lebanese girl with a CD onset at 13 months and in both her asymptomatic parents. The analysis detected an extremely rare homozygous variant in PTPN2: c.359C>T, p.(Ser120Leu) in the patient, while both her parents were heterozygous. This variant, located in the protein tyrosine phosphatase (PTP) domain within a highly conserved amino acid, is classified as VUS according to the American College of Medical Genetics (ACMG) criteria. To evaluate the hypothetical functional consequences of the identified variant, a quantitative expression analysis of PTPN2 was performed in blood tissues of the patient, her parents, and two healthy controls. PTPN2 expression was not noted in the patient compared to her parents and the normal controls, suggesting a functional PTPN2 impairment caused by c.359C>T. This variant c.359C>T, p.(Ser120Leu) in PTPN2 has never been previously described in the literature. Our report suggests an association of PTPN2: c.359C>T with early-onset CD.

克罗恩病 (CD) 是一种慢性特发性炎症性肠病，可影响胃肠道的任何部位。据报道，包括PTPN2在内的数百个候选基因座或基因与 CD 相关。对一名 13 个月大时出现 CD 病的 9 岁黎巴嫩女孩及其无症状父母进行了全外显子组测序 (WES)。分析在患者体内检测到极其罕见的PTPN2纯合变异：c.359C>T，p.(Ser120Leu)，而她的父母均为杂合子。该变体位于蛋白酪氨酸磷酸酶 (PTP) 结构域内的一个高度保守的氨基酸内，根据美国医学遗传学学院 (ACMG) 标准，该变体被归类为 VUS。为了评估所识别变异的假设功能后果，在患者、其父母和两名健康对照的血液组织中进行了PTPN2的定量表达分析。与她的父母和正常对照相比，患者中没有注意到PTPN2表达，表明c.359C>T 引起功能性PTPN2损伤。 PTPN2中的这种变体 c.359C>T, p.(Ser120Leu)以前从未在文献中描述过。我们的报告表明PTPN2 : c.359C>T 与早发性 CD存在关联。