講演情報
[P12-9]PRRT2関連発作性運動障害と16p11.2微小欠失症候群の新規併存例
○小松 和幸1, 福村 忍2, 皆川 公夫3, 中島 光子1, 才津 浩智1 (1.浜松医科大学 医学部 医化学講座, 2.札幌医科大学医学部 小児科学講座, 3.療養介護・医療型障害児入所施設 緑ヶ丘療育園)
【Background】 Clinical spectrum caused by pathogenic PRRT2 variants is designated as PRRT2-associated paroxysmal movement disorders, which include paroxysmal kinesigenic dyskinesia, benign familial infantile epilepsy, and infantile convulsions with choreoathetosis, and hemiplegic migraine. While heterozygous pathogenic PRRT2 variants and 16p11.2 microdeletion cause neurological diseases with the autosomal dominant manner, rare cases with bi-allelic PRRT2 variants or PRRT2 variants in combination with 16p11.2 microdeletion (hemizygous cases) have been reported to show more severe phenotypes. To date, only three hemizygous cases have been reported. 【Case】 A 22-year-old man presents with episodic ataxia (EA), paroxysmal kinesigenic dyskinesia, seizure, intellectual disability and autism spectrum disorder (ASD). He also has obesity, hypertension, hyperuricemia, and mild liver dysfunction. Exome sequencing revealed a c.649dup variant in PRRT2 in one allele and a de novo 16p11.2 microdeletion in another allele. 【Discussion】 EA was commonly shared among four hemizygous cases but it was rarely observed in heterozygous cases. Facial dysmorphism, ASD and adolescent onset obesity are characteristic findings in our case. Especially, facial dysmorphism and ASD have not been reported in heterozygous and biallelic cases, but those are common in 16p11.2 microdeletion. EA and ASD are characteristic features of hemizygous cases and some rare findings might be caused by haploinsufficiency of genes located at 16p11.2 locus.