Clinical phenotype and genetic mutation of fatty acid hydroxylase - associated neurodegeneration: analysis of four cases

Objective To report 4 cases of fatty acid hydroxylase - associated neurodegeneration (FAHN) and to summarize the clinical and genetic characteristics of FAHN by literatures review.  Methods Four cases of FAHN patients' clinical and family data were collected in detail. The gDNA of patients and their parents were extracted from peripheral blood. FA2H gene was conducted and followed by Sanger sequencing.  Results Among the 4 cases, 3 cases (Case 2, Case 3, Case 4) presented typical manifestations of FAHN while the other (Case 1) was atypical. Genetic sequencing showed FA2H gene mutation in all affected patients. Compound heterozygous mutation c.461G > A (p.Arg154His) and c.794T > G (p.Phe265Cys) were seen in Case 1. In Case 2, only one documented heterozygous mutation c.703C > T (p.Arg235Cys) was found, and dificit mutation was not found in single nucleotide polymorphism (SNP) chip test of the patient and her mother. Compound heterozygous mutation c.688G > A (p.Glu230Lys) and insertion mutation c.172_173insGGGCCAGGAC (p.Ile58ArgfsX47) were presented in Case 3. In Case 4, compound heterozygous mutation c.688G > A (p.Glu230Lys), c.968C > A (p.Pro323Gln) and c.976G > A (p. Gly326Asp) were seen, while his father was the carrier of c.688G > A (p.Glu230Lys) mutation and his mother was the carrier of c.968C > A (p.Pro323Gln) and c.976G > A (p.Gly326Asp) mutation. According to the standard of American College of Medical Genetics and Genomics (ACMG), c.461G > A (p.Arg154His) and c.794T > G (p.Phe265Cys) in Case 1, and c.703C > T (p.Arg235Cys) in Case 2 were considered as "likely pathogenic", while FA2H gene compound heterozygous mutation c.688G > A (p.Glu230Lys), insertion mutation c.172_173insGGGCCAGGAC (p.Ile58ArgfsX47) in Case 3 was as "pathogenic", and in Case 4, the FA2H gene mutation c.688G > A (p.Glu230Lys) and c.968C > A (p.Pro323Gln) were "pathogenic" and c.976G > A (p.Gly326Asp) was "likely pathogenic".  Conclusions FAHN has highly clinical and genetic heterogenieity in which spastic paraplegia is the main clinical presentation. In typing diagnosis for patietns with autosomal recessive herditary spastic paraplegia (HSP), especially combined with dyslalia, dysnoesia, and clinical features of white matter lesion and cerebellar atrophy, FA2H gene mutation-induced FAHN should be considered. DOI: 10.3969/j.issn.1672-6731.2017.07.010