Phenotypic and genetic analysis of a family with nonketotic hyperglycinemia caused by AMT gene mutation / 中华神经科杂志

ABSTRACT

Nonketotic hyperglycinemia (NKH) is a rare congenital metabolic disorder with low diagnostic rate. This article reported a case of NKH caused by AMT gene mutation. The child started with suspected neonatal sepsis, and then the condition deteriorated rapidly, including apnea, hiccup, coma, convulsion, etc. Blood glucose, ketone body, blood gas analysis of electrolytes, blood ammonia and so on were generally normal. Blood and urine screening results showed that glycine was slightly higher, and the ratio of cerebrospinal fluid to serum glycine concentration increased. Electroencephalogram showed outburst suppression. High total exome sequencing results showed that the maternal exon 3 c.664C>T(p.Arg222Cys) of AMT gene was pathogenic, and the paternal exon 3 c.793C>T(p.Arg265Cys) was suspected to be pathogenic, which was an autosomal recessive genetic disease with complex heterozygosis. The clinical diagnosis and treatment of this child and the characteristics of gene mutation are summarized.