Cobalamin C (cblC) disease and Kallmann syndrome (KS) are rare hereditary diseases. To date, no report has described the coexistence of those two genetic disorders in the same patient, or an association between them. We report the case of a 23-year-old woman with cblC defect and KS. She first presented mild memory problems in puberty, which worsened in adulthood to progressive memory loss accompanied by slow and unsteady walking, slow response, inattention, cognitive impairment, insomnia, no sense of smell, and the lack of spontaneous puberty. Laboratory tests revealed gonadotropin deficiency, a low estrogen level, and remarkably elevated serum homocysteine and serum and urine organic acid levels. Whole-exome sequencing detected compound heterozygous variants in MMACHC [c.398_399del (p.Gln133Argfs*4) and c.482G > A (p.Arg161Gln)] and heterozygous variants in PROKR2 [c.337T > C (p.Tyr113His)]. Thus, clinical and genetic examinations confirmed the cblC disease and KS diagnoses. This report on coexisting cblC disease and KS caused by different pathogenic genes in a single patient enriches the clinical research on these two rare genetic diseases.

钴胺素 C (cblC) 病和卡尔曼综合征 (KS) 是罕见的遗传性疾病。迄今为止，还没有报告描述同一患者中这两种遗传疾病的共存，或它们之间的关联。我们报告了一名患有 cblC 缺陷和 KS 的 23 岁女性的病例。她在青春期首次出现轻度记忆问题，成年后恶化为进行性记忆丧失，伴有缓慢和不稳定的行走、反应缓慢、注意力不集中、认知障碍、失眠、嗅觉丧失和缺乏自发性青春期。实验室检查显示促性腺激素缺乏、雌激素水平低、血清同型半胱氨酸以及血清和尿液有机酸水平显着升高。全外显子组测序检测到MMACHC 中的复合杂合变异[c.398_399del (p.Gln133Argfs*4) 和 c.482G > A (p.Arg161Gln)] 和PROKR2 中的杂合变体[c.337T > C (p.Tyr113His)]。因此，临床和基因检查证实了 cblC 疾病和 KS 诊断。本次关于同一患者不同致病基因引起的cblC病和KS共存的报道丰富了这两种罕见遗传病的临床研究。