Hartnup disease combined with iminocaciduria: two novel mutations in the SLC6A19 gene (a case report)

Purpose To report a case of Hartnup disease combined with iminocaciduria, and to explore its clinical manifestations and genetic mutations. Methods Clinical data of the patient were collected, whole-exome sequencing was performed using high-throughput sequencing technology to detect SLC6A19 gene mutations. Sanger sequencing was used for family verification, and software was employed to predict protein structure and function. Results The patient exhibited intermittent pellagra, ataxia, and psychiatric symptoms. Genetic sequencing revealed three heterozygous mutations in the SLC6A19 gene: a heterozygous missense mutation c.169C > T (p.Ary57Cys), a heterozygous missense mutation c.1802C > A (p.A601D), and a heterozygous splicing mutation c.1378 + 5G > A. The c.169C > T and c.1378 + 5G > A mutations were inherited from the father, whereas the mutation c.1802C > A was passed down from the mother. Bioinformatics-based protein function prediction indicated that both the c.169C > T (p.R57C) and c.1802C > A (p.A601D) mutations are harmful. Furthermore, the levels of 5-oxoproline and proline in the urine were elevated. Conclusion The typical manifestations of Hartnup disease include intermittent pellagra, ataxia, and psychiatric symptoms. The SLC6A19 mutations c.1802C > A and c.1378 + 5G > A are novel, and this case expands the genetic spectrum of the disease.