Clinical and genetic analysis of two Chinese patients with isovaleric acidemia and review of literature / 中华实用儿科临床杂志

ABSTRACT

Objective To discuss the clinical features and treatment of isovaleric academia (IVA) patients,and to gain more comprehensive understanding of isovaleryl-CoA dehydrogenase(IVD) mutation in 2 siblings in order to raise awareness to prevent the occurrence of IVA.Methods The clinical history and laboratory test of 2 cases of children with IVA were carried out.The exons and neighboring introns of IVD gene of the whole family were PCR-amplified for DNA sequencing.The literature review of IVA in China was also conducted.Results Organic acid analysis of urine by GC/MS for both siblings showed extremely elevated concentrations of isovaleric glycine.For the older sibling,an acute episode of IVA caused severe metabolic stress and eventually death in the neonatal period.However,the disease was well-controlled for the younger sibling due to timely treatment and follow-up care for 2 years.The DNA sequencing of the IVD gene in the family revealed a novel c.1016G ＞ A(C339Y) heterozygous mutation in mother and both of the siblings.No IVD mutation was detected in father or in any of the 50 cases of healthy controls.According to literature review,15 cases of IVA were reported in recent 15 years in China,including neonatal onset (11 cases),acute episode (12 cases),odor of sweaty feet (12 cases),pancytopenia (9 cases),hyperammonemia (5 cases),hypocalcemia (6 cases),and 6 cases of death were reported.Additionally,5 cases that received treatment of BCAA-free formula milk showed positive outcome.However,only 2 cases were followed up for more than 2 years.Conclusions Two new IVA patients carrying c.1016G ＞ A(C339Y) mutation were reported in China.The mutation may lead to conformational change and functional deficient of the IVD protein.It is also necessary to point out that using direct DNA sequencing can not identify all patients with IVA due to limitations of this technology,and thus clinicians should be aware of the possibility of genetic misdiagnosis.Moreover,there is a trend of increasing IVA in China in recent years.