Expanding the clinical and neuroimaging features of NKX6-2-related hereditary spastic ataxia type 8.

Pathogenic variants in NKX6-2 gene causing autosomal recessive spastic ataxia type 8 with hypomyelinating leukodystrophy have been reported in few families around the world. In this study, we performed Whole Exome Sequencing and identified a novel missense variant, c.501C > G; p.(Phe167Leu), in two affected siblings with main manifestations of global developmental delay, motor regression, hypotonia, clonus in lower limbs and muscle bulk atrophy especially in the upper limbs, spasticity and contracture, scoliosis, hip dislocation, oculomotor apraxia, horizontal and vertical nystagmus. In addition, wrist and foot drop due to peripheral axonal neuropathy were observed in these patients as a new clinical finding and cerebellar white matter involvement in brain Magnetic Resonance Imaging (MRI) as new imaging finding. Therefore, we expanded the manifestations of NKX6-2-related disorders in this manuscript.