Sudden Infant Death with Dysgenesis of the Testes syndrome (SIDDT) is a very rare condition associated with biallelic pathogenic variants in the TSPYL1 gene first reported in 2004. It is characterized by sudden cardiac or respiratory arrest, disordered testicular development, neurologic dysfunction, and is uniformly fatal before the age of 12 months. There were previously 21 reported cases of SIDDT in the literature, all from nine Old Order Amish families published in a single paper. In this report, we describe a non‐Amish, phenotypically female infant with poor feeding and abnormal motor movements noted at birth. Initial testing showed that she had a 46,XY chromosome complement, and chromosomal microarray showed a significant absence of heterozygosity (AOH) totalling roughly 600 Mb across multiple different chromosomes, indicating consanguinity. Further workup with exome sequencing revealed homozygosity for a frameshift variant in TSPYL1 (c.725_726delTG, p.Val242GlufsTer52) consistent with a diagnosis of SIDDT, explaining many of her clinical features. However, she was also noted to have a mild T‐cell lymphopenia and developed intractable epilepsy after hospital discharge. These features have not previously been reported in SIDDT and may represent phenotypic expansion. To our knowledge, this patient is the 22nd case of SIDDT to be reported in the literature, and the first to be of non‐Amish heritage.

中文翻译：

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非阿米什语婴儿突然死亡并伴有睾丸综合征发育异常的病例报告。

婴儿突然死亡与睾丸综合征的发育不全（SIDDT）是与TSPYL1中双等位基因致病变异相关的非常罕见的疾病该基因于2004年首次报道。它的特征是心脏或呼吸骤停，睾丸发育紊乱，神经功能障碍，并且在12个月大之前完全致命。以前在文献中报告过21例SIDDT病例，全部来自9个Old Order Amish家庭。在本报告中，我们描述了一个非阿米什人，具有表型的女婴，其出生时注意到喂养不良和运动异常。最初的测试显示她有46，XY染色体互补，并且染色体微阵列显示在多个不同的染色体上总计约600 Mb的杂合性（AOH）明显缺失，表明是血缘关系。外显子组测序的进一步研究揭示了TSPYL1中移码变体的纯合性（c.725_726delTG，p.Val242GlufsTer52）与SIDDT的诊断一致，解释了她的许多临床特征。但是，她也被发现患有轻度T细胞淋巴细胞减少症，出院后发展为顽固性癫痫病。这些功能以前未在SIDDT中进行过报道，可能代表了表型扩展。据我们所知，该患者是文献中报道的22例SIDDT病例，也是首例非阿米什人的遗产。