Objective: To report a family diagnosed with Allan-Herndon-Dudley syndrome (AHDS) due to SLC16A2 gene mutation and to summarize the phenotypes, genotypes, diagnosis, treatment, and prognosis. Methods: The clinical features of a family of AHDS diagnosed in Xiangya Hospital of Central South University in November 2017 were analyzed. Related literature was searched at Online Mendelian Inheritance in Man (OMIM), PubMed, CNKI and Wanfang database (from the establishment of databases to June 2018) by using "Allan-Herndon-Dudley syndrome" , and "AHDS" as keywords and the case reports from April 2013 to June 2018 were reviewed. Results: The proband was a boy aged 8 months who presented with global developmental retardation, inability to hold up the head, disability to sit independently or grab, no language development, elongated face, big ears, esotropia, scoliosis, hypotonia in the trunk, hypertonia in extremities, and hyperreflexia. Brain magnetic resonance imaging (MRI) showed widening of the extracerebral space and delayed myelination. Thyroid function tests revealed increased FT3, decreased FT4 and normal TSH. Whole exome sequencing (WES) revealed the SLC16A2 gene c.431-1 (IVS1) G>C hemizygous mutation. The infant's mother and grandmother are carriers, but whose father had no related mutation. One uncle from maternal side had severe psychomotor retardation as well as dystonia and died at one year of age with unknown etiology. A total of 97 articles were retrieved in which 19 case reports were reviewed. Forty-two cases (22 from 8 families and 20 sporadic) were reported. Among these 42 cases (all males), all of them presented with moderate to severe cognitive dysfunction, 15 with seizures; 36 were bedridden, only 4 could walk; 31 had no language development, 2 could speak sentences, 4 could speak few words, 1 had babbling sounds. Furthermore,16 had microcephaly, 18 had facial dysmorphism, 6 had esotropia, 2 had hearing loss,14 had scoliosis, 11 had joint contracture, 30 had low body weight/muscle wasting, 37 had hypotonia in trunk or extremities, 32 had progressive spastic paraplegia or hypertonia. In terms of thyroid function, 33 had abnormal results, within whom 30 had increased T3, 25 had decreased T4 and 3 had increased TSH. Brain MRI showed delayed myelination in 22 cases, within which one normalized with development. Genetic tests showed that 31 had missense mutation (14 sporadic), 5 had deletion mutation (3 sporadic, and 1 due to frameshift mutation), 5 had insertion mutation (2 sporadic), and 1 had repeated mutation. The prognosis was poor as patients often died of recurrent respiratory tract infection. Conclusions: The main clinical manifestations of AHDS are severe global developmental retardation, hypotonia, spastic paraplegia, abnormal serum levels of thyroid hormone and delayed brain myelination. SLC16A2 c. 431-1 (IVS1) G > C mutation is accountable for this disease.
目的： 总结SLC16A2基因突变致Allan-Herndon-Dudley综合征一家系临床特征、基因突变特点、诊断、治疗及预后。 方法： 总结中南大学湘雅医院儿科2017年11月确诊的Allan-Herndon-Dudley综合征（AHDS）一家系的临床资料。以"艾伦-赫恩登-达得利综合征""Allan-Herndon-Dudley syndrome""AHDS"为关键词查阅在线人类孟德尔遗传数据库（OMIM）和PubMed数据库及中国知识基础设施工程（CNKI）数据库、万方数据库建库至2018年6月相关文献，并对2013年4月至2018年6月的病例报道文献进行总结。 结果： 先证者男，8月龄，临床表现为智力及运动发育迟滞、竖头欠稳、不能独坐、双上肢不能抓物、无语言，长脸、大耳、双眼稍内斜、脊柱侧弯、躯干肌张力低下、四肢肌张力增高、双下肢腱反射亢进；头颅磁共振成像（MRI）示脑外间隙增宽、髓鞘发育延迟；甲状腺功能：三碘甲状腺原氨酸（T3）增高、甲状腺素（T4）降低、促甲状腺激素（TSH）正常；家系全外显子测序发现患儿SLC16A2基因（NM_006517）c.431-1（IVS1）G>C半合子突变，父亲无基因突变，母亲和外祖母为携带者；先证者舅舅患有严重智力及运动发育迟滞、全身肌张力低下，1岁时不明原因死亡。检索相关文献97篇，最终纳入病例报道文献19篇，共报道42例患者（包括8个家系22例患者及20例散发患者)。已报道的42例患者（均为男性），中至重度认知功能障碍42例，抽搐15例；长期卧床36例，可独走4例；语言缺失31例，可说句子2例，说词语4例，呀呀学语1例；小头畸形16例，面容异常18例，双眼内斜6例，听力障碍2例，脊柱侧弯14例，关节挛缩11例，低体重或肌容量减少30例，全身或躯干肌张力低下37例，病程中出现痉挛性截瘫或肌张力增高32例；甲状腺功能异常33例，其中T3增高30例，T4降低25例，TSH增高3例；头颅MRI示22例髓鞘发育延迟，其中1例随年龄增长髓鞘发育至正常；基因结果：错义突变31例（散发14例），缺失突变5例（散发3例，有1例缺失突变后导致框移突变），插入突变5例（散发2例），重复突变1例（散发）。该病预后不佳，患儿常因呼吸道反复感染而死亡。 结论： Allan-Herndon-Dudley综合征的主要临床表现为严重发育迟缓，不能抬头、独坐、独站、独走，语言发育延迟至语言缺失，出生后全身肌张力低下、进行性痉挛性截瘫、血清甲状腺激素异常、头颅MRI示髓鞘发育延迟，SLC16A2 c.431-1（IVS1）G>C突变是其致病原因。.
Keywords: Allan-Herndon-Dudley syndrome; High-throughput nucleotide sequencing; Mental retardation; SLC16A2 gene.