The etiology of central diabetes insipidus (DI) is classified into (1) idiopathic, (2) familial, and (3) secondary. Of these, familial central diabetes insipidus shows an autosomal dominant inheritance. We herein report a case in which this disease was diagnosed based on a family history of nocturnal enuresis. A 40-year-old man had had symptoms of polydipsia, polyuria and nocturia since childhood and found that his daughter had the same symptoms. Despite reaching nine years old, his daughter’s nocturnal enuresis still had not improved, resulting in her consulting a pediatrician. She was suspected of having familial neurohypophyseal diabetes insipidus (FNDI) based on her family history and was referred along with her father for a detailed examination and treatment. A hypertonic saline load test (HSLT) to evaluate the arginine vasopressin (AVP) reaction was performed in both the proband and his daughter. The results showed no increase in AVP levels in response to high plasma osmolality. The water deprivation test (WDT) revealed he was suffering from partial DI. Based on the above findings and considering the possibility of familial central diabetes insipidus, we performed a gene mutation analysis of AVP-neurophysin II (NPII). Both the father and daughter had an exon 2 abnormality in this gene (c232_234delGAG; pGlu78del), and this gene mutation is known to cause NPII protein abnormality, abolishing the function of AVP as a carrier protein. This case was considered to have provided an opportunity to understand the role of an NPII gene abnormality in familial central diabetes insipidus.

中枢性尿崩症 (DI) 的病因分为 (1) 特发性、(2) 家族性和 (3) 继发性。其中，家族性中枢性尿崩症呈常染色体显性遗传。我们在此报告一例根据夜间遗尿家族史诊断出该病的病例。一名40岁的男子，从小就有烦渴、多尿、夜尿的症状，发现自己的女儿也有同样的症状。女儿虽然已经九岁了，但夜尿依然没有好转，只好去看儿科医生。根据她的家族史，她被怀疑患有家族性神经垂体性尿崩症（FNDI），并与她的父亲一起被转诊进行详细检查和治疗。先证者和他的女儿都进行了高渗盐水负荷试验 (HSLT) 以评估精氨酸加压素 (AVP) 反应。结果表明，高血浆渗透压导致 AVP 水平没有增加。缺水测试 (WDT) 显示他患有部分 DI。基于上述发现并考虑家族性中枢性尿崩症的可能性，我们对 AVP-neurophysin II (NPII) 进行了基因突变分析。父亲和女儿在该基因中都有一个外显子2异常（c232_234delGAG；pGlu78del），并且已知该基因突变会导致NPII蛋白异常，从而破坏了AVP作为载体蛋白的功能。该病例被认为为了解 NPII 基因异常在家族性中枢性尿崩症中的作用提供了机会。