Speech and language impairment is core in Koolen-de Vries syndrome (KdVS), yet only one study has examined this empirically. Here we define speech, language, and functional/adaptive behaviour in KdVS; while deeply characterising the medical/neurodevelopmental phenotype in the largest cohort to date. Speech, language, literacy, and social skills were assessed using standardised measures, alongside an in-depth health and medical questionnaire. 81 individuals with KdVS were recruited (35 female, mean age 9y 10mo), 56 of whom harboured the typical 500–650 kb 17q21.31 deletion. The core medical phenotype was intellectual disability (largely moderate), eye anomalies/vision disturbances, structural brain anomalies, dental problems, sleep disturbance, musculoskeletal abnormalities, and cardiac defects. Most were verbal (62/81, 76.5%), while minimally-verbal communicators used alternative and augmentative communication (AAC) successfully in spite of speech production delays. Speech was characterised by apraxia (39/61, 63.9%) and dysarthria (28/61, 45.9%) in verbal participants. Stuttering was described in 36/47 (76.6%) verbal participants and followed a unique trajectory of late onset and fluctuating presence. Receptive and expressive language abilities were commensurate with one another, but literacy skills remained a relative weakness. Social competence, successful behavioural/emotional control, and coping skills were areas of relative strength, while communication difficulties impacted daily living skills as an area of comparative difficulty. Notably, KdVS individuals make communication gains beyond childhood and should continue to access targeted therapies throughout development, including early AAC implementation, motor speech therapy, language/literacy intervention, as well as strategies implemented to successfully navigate activities of daily living that rely on effective communication.

言语和语言障碍是 Koolen-de Vries 综合征 (KdVS) 的核心，但只有一项研究对此进行了实证检验。在这里，我们定义了 KdVS 中的语音、语言和功能/适应行为；同时在迄今为止最大的队列中深入描述医学/神经发育表型。使用标准化措施以及深入的健康和医疗问卷评估言语、语言、读写能力和社交技能。招募了 81 名 KdVS 患者（35 名女性，平均年龄 9 岁 10 个月），其中 56 名携带典型的 500-650 kb 17q21.31 缺失。核心医学表型是智力障碍（大部分为中度）、眼睛异常/视力障碍、脑结构异常、牙齿问题、睡眠障碍、肌肉骨骼异常和心脏缺陷。大多数是口头的（62/81，76.5%），尽管言语产生延迟，但最少口语交流者成功地使用了替代和增强交流 (AAC)。言语参与者的言语特征是失用症 (39/61, 63.9%) 和构音障碍 (28/61, 45.9%)。36/47 (76.6%) 的口吃参与者描述了口吃，并遵循迟发和波动存在的独特轨迹。语言接受能力和表达能力相称，但识字能力仍然是一个相对薄弱的环节。社交能力、成功的行为/情绪控制和应对技巧是相对优势的领域，而沟通困难影响日常生活技能是相对困难的领域。尤其，