Adenylosuccinate lyase deficiency is a rare autosomal recessive disorder of purine metabolism. The disorder manifests with developmental delay, postnatal microcephaly, hypotonia, involuntary movements, epileptic seizures, ataxia and autistic features. Paroxysmal non-epileptic motor events are not a typical presentation of the disease. We describe an 8-year-old boy who presented with an infantile onset of prolonged episodes of multifocal sustained myoclonic tremor lasting from minutes to days on a background of global developmental delay and gait ataxia. Ictal EEG during these episodes was normal. Ictal surface EMG of the involved upper limb showed a muscular activation pattern consistent with cortical myoclonus. Brain MRI showed mild cerebral atrophy. Whole exome sequencing revealed a novel homozygous variant in the ADSL gene: c.1027G > A; p. Glu343Lys, inherited from each heterozygous parent. There was a marked elevation of urine succinyladenosine, confirming the diagnosis of adenylosuccinate lyase deficiency. In conclusion, myoclonic tremor status expands the spectrum of movement disorders seen in adenylosuccinate lyase deficiency.

腺苷琥珀酸裂合酶缺乏症是一种罕见的嘌呤代谢常染色体隐性遗传疾病。该疾病表现为发育延迟，产后小头畸形，肌张力低下，不自主运动，癫痫发作，共济失调和自闭症。阵发性非癫痫性运动事件不是该疾病的典型表现。我们描述了一个8岁的男孩，在全球发展延迟和步态共济失调的背景下，婴儿发作多发性持续性肌阵挛性震颤的发作持续数分钟至数天。这些发作期间的发作性脑电图正常。累及的上肢的肌表面肌电图显示出与皮质肌阵挛相一致的肌肉激活模式。脑MRI显示轻度脑萎缩。整个外显子组测序揭示了ADSL中的新型纯合子变体基因：c.1027G> A；p。Glu343Lys，继承自每个杂合的亲本。尿中琥珀酰腺苷含量明显升高，证实了腺苷酸琥珀酸裂合酶缺乏症的诊断。总之，肌阵挛性震颤状态扩大了腺苷酸琥珀酸裂合酶缺乏症所见的运动障碍的范围。