Alopecia, neurologic defects, and endocrinopathy (ANE) syndrome is a rare ribosomopathy known to be caused by a p.(Leu351Pro) variant in the essential, conserved, nucleolar large ribosomal subunit (60S) assembly factor RBM28. We report the second family of ANE syndrome to date and a female pediatric ANE syndrome patient. The patient presented with alopecia, craniofacial malformations, hypoplastic pituitary, and hair and skin abnormalities. Unlike the previously reported patients with the p.(Leu351Pro) RBM28 variant, this ANE syndrome patient possesses biallelic precursor messenger RNA (pre-mRNA) splicing variants at the 5′ splice sites of exon 5 (ΔE5) and exon 8 (ΔE8) of RBM28 (NM_018077.2:c.[541+1_541+2delinsA]; [946G > T]). In silico analyses and minigene splicing experiments in cells indicate that each splice variant specifically causes skipping of its respective mutant exon. Because the ΔE5 variant results in an in-frame 31 amino acid deletion (p.(Asp150_Lys180del)) in RBM28 while the ΔE8 variant leads to a premature stop codon in exon 9, we predicted that the ΔE5 variant would produce partially functional RBM28 but the ΔE8 variant would not produce functional protein. Using a yeast model, we demonstrate that the ΔE5 variant does indeed lead to reduced overall growth and large subunit ribosomal RNA (rRNA) production and pre-rRNA processing. In contrast, the ΔE8 variant is comparably null, implying that the partially functional ΔE5 RBM28 protein enables survival but precludes correct development. This discovery further defines the underlying molecular pathology of ANE syndrome to include genetic variants that cause aberrant splicing in RBM28 pre-mRNA and highlights the centrality of nucleolar processes in human genetic disease.

脱发、神经系统缺陷和内分泌病 (ANE) 综合征是一种罕见的核糖体病，已知由基本、保守的核仁大核糖体亚基 (60S) 组装因子 RBM28 中的 p.(Leu351Pro) 变体引起。我们报告了迄今为止的第二个 ANE 综合征家族和一名女性儿科 ANE 综合征患者。患者表现为脱发、颅面畸形、垂体发育不全以及头发和皮肤异常。与先前报道的 p.(Leu351Pro) RBM28变异患者不同，该 ANE 综合征患者在外显子 5 (ΔE5) 和外显子 8 (ΔE8) 的 5' 剪接位点具有双等位基因前体信使 RNA (pre-mRNA) 剪接变异体。RBM28(NM_018077.2:c.[541+1_541+2delinsA];[946G > T])。计算机中的计算机分析和小基因剪接实验表明，每个剪接变体特异地导致跳过其各自的突变外显子。因为在符合读框的31个氨基酸缺失的变体ΔE5结果（第（Asp150_Lys180del））在RBM28虽然 ΔE8 变体导致外显子 9 中的过早终止密码子，但我们预测 ΔE5 变体会产生部分功能性的 RBM28，但 ΔE8 变体不会产生功能性蛋白质。使用酵母模型，我们证明 ΔE5 变体确实会导致整体生长和大亚基核糖体 RNA (rRNA) 生产和前 rRNA 加工减少。相比之下，ΔE8 变体相对无效，这意味着部分功能性的 ΔE5 RBM28 蛋白能够存活但妨碍正确发育。这一发现进一步定义了 ANE 综合征的潜在分子病理学，包括导致RBM28前体 mRNA异常剪接的遗传变异，并突出了核仁过程在人类遗传疾病中的中心地位。