男,2岁。因皮肤瘀斑1月,呕吐20余天入院。第2胎,第2产,足月顺产,母乳喂养。自生后5个月开始,经常出现皮肤瘀斑,碰撞后易起血肿,外伤后皮肤出血不止。父母健康,近亲婚配(患儿祖母和外祖母为表姐妹),有一姐身体健康,无相似病史。体检·神清,精神差,营养发育一般,腹部及四肢皮肤可见散在大小不等的皮下瘀斑,压之不退色,颈部抵抗感(±)。心肺无异常。腹软,肝脾未触及。四肢活动好,手指端采血部位出血不止(已采血2小时),克氏 Male, 2 years old. Due to skin ecchymosis January, vomiting more than 20 days admitted to hospital. 2nd, 2nd, full term, breastfeeding. 5 months after birth, often appear skin ecchymosis, easy to hematoma after the collision, skin bleeding after trauma more than. Parents health, cousins ​​marriage (children’s grandmother and grandmother as cousins), a sister healthy, no similar medical history. Physical examination · Clear, poor spirit, general nutritional development, abdomen and extremity skin scattered in varying sizes of subcutaneous ecchymosis, pressure of fade, neck resistance (±). No abnormal heart and lung. Abdomen soft, liver and spleen not touched. Extremity activities, bleeding at the finger end of the blood more than (blood 2 hours), Kirschner