[Clinical characteristics and treatment responses of X-linked thrombocytopenia]

To analyze the clinical and molecular characteristics of patients with X-linked thrombocytopenia (XLT) and their responsiveness to treatment with various doses of corticosteroids or intravenous immunoglobulin (IVIG) separately.

Data from 15 XLT patients who were hospitalized in Children's Hospital Affiliated to Chongqing Medical University from March 2010 to July 2014 were analyzed retrospectively, including clinical manifestations, scores, peripheral blood, immunological functions, responses to IVIG and steroid treatment with various doses and duration.

All 15 XLT patients met the inclusion criteria and showed microthrombocytopenia with or without mild-to-moderate eczema or minor infections. Platelet counts ranged from (8-80) × 10⁹/L. The platelet volume value ranged between 5.6 and 10.9 fl (normal range: 9.4-12.5 fl). Raised serum IgG was found in 5 cases, while low serum IgG was found in 2 cases. WAS gene analysis revealed missense mutations in 14 patients, including 4 hotspots (V75M, R86C, R86H, R86L) and 1 novel mutation (Y107C). Flow cytometer analysis of 13 patients showed various amounts of WAS protein (WASP) expression, 2 patients had normal amounts of WASP expression, 5 had reduced amounts, and 6 had absent WASP expression. Their responses to individual steroid and IVIG treatment with various doses and duration were also reviewed. Fourteen patients who were misdiagnosed as immune thrombocytopenic purpura at first received 28 courses of steroids and (or) 47 courses of IVIG treatment. The post-treatment platelet counts of 1 000-2 000 mg/(kg × d) IVIG(25 courses) at 2-7 d and 8-14 d time points were (60 ± 10) × 10⁹/L and (41 ± 7) × 10⁹/L, which indicate a significantly better responsiveness than those by [(31 ± 7) × 10⁹/L, (21 ± 2) × 10⁹/L] of 400-500 mg/(kg·d) IVIG(22 courses) (Z = -4.419, -1.592;P = 0.002,0.011). However, there were no significant differences between the responsiveness of 3 doses [1-2 mg/(kg·d)(8 courses), 3-6 mg/(kg·d) (11 courses) and 20-30 mg/(kg × d)(9 courses)] of steroids (F = 0.387,0.252;P = 0.980,0.761) at 2-7 d and 8-14 d time points. The platelet counts gradually decreased to the primary level at 15-30 d after any doses of steroids and (or) IVIG treatment. The effective rate of 1 000-2 000 mg/(kg × d) IVIG treatment was 18/25, which was significantly higher than that (2/22) of 400-500 mg/(kg × d) (χ² = 9.836, P = 0.008). The effective rate of 20-30 mg/(kg × d) steroids treatment (7/9) was relatively higher than 1-2 mg/(kg × d) (4/8) and 3-6 mg/(kg × d) (6/11) with no significant difference (χ⁹ = 3.235, P = 0.581). After the treatment with steroids and /or IVIG 14 cases with hemorrhage were all improved.

The clinical characteristics of X-linked thrombocytopenia were microthrombocytopenia with or without mild-to-moderate eczema or minor infections. WAS gene and WASP analysis were diagnostic methods. There were no significant differences between the responsiveness of 3 doses of steroids; 1 000-2 000 mg/(kg·d) IVIG had a significantly better responsiveness. However, IVIG and steroids with any dose and duration may only transiently increase peripheral platelet level of XLT patients.