A homozygous G insertion in MPLKIP leads to TTDN1 with the hypergonadotropic hypogonadism symptom

BACKGROUND: Trichothiodystrophy nonphotosensitive 1 (TTDN1) is a disease with mental retardation, brittle hair. Some cases of the diseases are caused by mutations of the MPLKIP gene. METHODS: We carefully identified the clinic characteristics, the sulfur level and pattern of the hair shafts of a female patient of with the symptom of hypergonadotropic hypogonadism, and of her parents and brother whose are healthy. We also collected the blood sample of the patient and performed the exon sequencing. One G insertion in MPLKIP was identified after analyzing the obtained exon sequencing profile. The G insertion sites in the patient, her parents and brother, were verified using Sanger sequencing. The G insertion in MPLKIP were compared to the dbSNP. RESULTS: The female patient of TTDN1 carries a homozygous G insertion (rs747470385) in the MPLKIP gene. The parents and brother of the patient are heterozygous carriers of the same mutation, but are healthy. The hair shafts of the patient had a tiger-tail pattern with relatively low sulfur levels. To the best of our knowledge, this is the first report that autosomal recessive inheritance of the G insertion in the MPLKIP gene results in TTDN1. CONCLUSION: Our results indicate that the homozygotic G insertion in MPLKIP results in the TTDN1 with hypergonadotropic hypogonadism, while heterozygous carriers of the same mutation have no symptoms and healthy. These results provide novel insights into the association of mutations in MPLKIP and TTDN1 with hypergonadotropic hypogonadism.