Neurology 2019 07 13;93(3):e237-e251. Epub 2019 Jun 13.
From the Departments of Human Genetics (A.F., S. Mitsuhashi, T.M., A.T., S. Miyatake, N. Miyake, N. Matsumoto) and Neurosurgery (M.S.), Yokohama City University Graduate School of Medicine; Departments of Functional Neurosurgery (T.H., H. Shirozu, H.M., M.F., S.K.) and Child Neurology (J.T.), Epilepsy Center, National Hospital Organization Nishiniigata Chuo Hospital Niigata, Japan; Department of Pediatrics and Neurology (M.S.), Wayne State University, Children's Hospital of Michigan, Detroit Medical Center; Department of Pediatrics (M.K.), Showa University School of Medicine, Tokyo; Department of Biochemistry (M.N., H. Saitsu), Hamamatsu University School of Medicine; and Clinical Research Institute (Y.T.), Kanagawa Children's Medical Center, Yokohama, Japan.
Objective: Intensive genetic analysis was performed to reveal comprehensive molecular insights into hypothalamic hamartoma (HH).
Methods: Thirty-eight individuals with HH were investigated by whole exome sequencing, target capture-based deep sequencing, or single nucleotide polymorphism (SNP) array using DNA extracted from blood leukocytes or HH samples.
Results: We identified a germline variant of , which encodes a ciliary protein, and 2 somatic variants of , which forms part of the RAS/mitogen-activated protein kinase (MAPK) pathway, as well as variants in known genes associated with HH. An SNP array identified (among 3 patients) one germline copy-neutral loss of heterozygosity (cnLOH) at 6p22.3-p21.31 and 2 somatic cnLOH; one at 11q12.2-q25 that included , which encodes a ciliary motor protein, and the other at 17p13.3-p11.2. A germline heterozygous variant and an identical somatic variant of arising from cnLOH at 11q12.2-q25 were confirmed in one patient (whose HH tissue, therefore, contains biallelic variants of ). Furthermore, a combination of a germline and a somatic variant was detected in another patient.
Conclusions: Overall, our cohort identified germline/somatic alterations in 34% (13/38) of patients with HH. Disruption of the Shh signaling pathway associated with cilia or the RAS/MAPK pathway may lead to the development of HH.