Supplementary Material for: Genotype-phenotype analysis and new clinical findings in a series of 24 patients presenting with Noonan syndrome and related disorders

Introduction: RASopathies are a heterogeneous group of conditions of the Ras/MAPK pathway presenting with overlapping features such as growth deficiency, neurodevelopmental disorders, cardiac defects, craniofacial dysmorphisms, cutaneous and ocular abnormalities, and increased cancer risk.
Methods: This retrospective study analyzed the medical records regarding clinical and molecular data from 2018 to 2024 in a single center for rare diseases of individuals diagnosed with Noonan syndrome and related disorders previously submitted to diagnostic molecular analysis through Next Generation Sequencing techniques.
Results: 24 patients were enrolled with an even sex ratio distribution and ages ranging from one month to 16 years at first evaluation. The main reason for referral was diagnostic assessment due to a combination of dysmorphic features (24/24; 100%), growth deficiency (18/24; 75%), neurodevelopmental disorders (15/24; 62.5%), and/or heart disease (13/24; 54.1%). Final diagnoses included 15 individuals with Noonan syndrome (nine with variants in PTPN11, two in SOS1, and one each in LZTR1, A2ML1, and MRAS, besides one with variants in both LZTR1 and SOS1), two with Noonan syndrome with multiple lentigines (both with variants in PTPN11), two with Neurofibromatosis-Noonan (NF1), two with Cardiofaciocutaneous syndrome (BRAF), and one each with Noonan syndrome-like with loose anagen hair (PPP1CB), Noonan syndrome-like (CBL), and Costello syndrome (HRAS); one individual presented with a double diagnosis of Noonan and Klinefelter syndromes.
Discussion/Conclusion: Three pairs of unrelated patients presented recurrent variants in the PTPN11 gene, partially concordant in phenotypic correlation among the pairs but not fully concordant compared to previously described cases in the literature. Undescribed features in this group included myopathy and megacolon in a patient with Noonan syndrome-like, hypogonadotropic hypogonadism, and azoospermia in a patient with Noonan syndrome-like with loose anagen hair, and schizophrenia in a patient with Costello syndrome. One patient with Noonan syndrome had a novel variant of the A2ML1 gene (c.1829G>A), but the variant was strictly of uncertain significance, while c.2033G>A in the LZTR1 gene and c.1A>G in the NF1 gene are variants for the first time associated with features of Noonan syndrome.

引言：RAS病（RASopathies）是一类累及Ras/MAPK信号通路的异质性疾病群，临床表现存在重叠特征，包括生长发育迟缓、神经发育障碍、心脏畸形、颅面畸形、皮肤与眼部异常以及癌症风险升高。
方法：本回顾性研究分析了某罕见病单中心2018年至2024年的病历资料，纳入对象为经下一代测序技术完成诊断性分子检测、确诊为努南综合征（Noonan syndrome）及相关疾病的患者，涵盖其临床与分子数据。
结果：本研究共纳入24例患者，性别比例均衡，首次评估时年龄为1月龄至16岁。患者转诊的主要原因为联合出现以下表现需明确诊断：畸形特征（24/24；100%）、生长发育迟缓（18/24；75%）、神经发育障碍（15/24；62.5%）及/或心脏疾病（13/24；54.1%）。最终诊断结果如下：15例确诊为努南综合征（其中9例存在PTPN11基因变异、2例存在SOS1基因变异，LZTR1、A2ML1、MRAS基因变异各1例，另有1例同时存在LZTR1与SOS1基因变异）；2例为多发黑子型努南综合征（均存在PTPN11基因变异）；2例为神经纤维瘤病-努南综合征（NF1）；2例为心面皮肤综合征（BRAF）；努南综合征伴毛发生长松脱症（PPP1CB）、类努南综合征（CBL）、科斯特洛综合征（HRAS）各1例；另有1例同时确诊为努南综合征与克兰费尔特综合征。
讨论与结论：三对无亲缘关系的患者均存在PTPN11基因复发性变异，每对患者间的表型关联存在部分一致性，但与文献中已报道的病例相比并不完全一致。本研究队列中还发现了此前未被报道的表型：1例类努南综合征患者合并肌病与巨结肠；1例伴毛发生长松脱症的类努南综合征患者合并促性腺激素低下性腺功能减退症与无精子症；1例科斯特洛综合征患者合并精神分裂症。1例努南综合征患者存在A2ML1基因的新变异（c.1829G>A），但该变异的临床意义尚不明确；LZTR1基因的c.2033G>A变异与NF1基因的c.1A>G变异均为首次被报道与努南综合征表型相关。