Ears of the Lynx Sign in Lipoyl Transferase-2 (LIPT2) Deficiency

A 4-year-old girl presented with global developmental delay, motor impairment, and tone abnormalities. There was significant family history of similar complaints in her younger sibling. On examination, she had normal head circumference, intermittent nystagmus, upper-limb dystonia, and lower-limb spasticity. Biochemical analysis revealed mild hyperammonemia and mild hyperlactatemia. Noncontrast computed tomography (NCCT) brain showed bilateral basal ganglia calcification [Figure 1a]. Magnetic resonance imaging revealed thinning of corpus callosum, periventricular cystic changes, and ‘ears of the lynx’ sign [Figure 1b-d]. Exome sequencing revealed a novel, pathogenic, homozygous missense variation c.472C>A; p.Arg158Ser in exon-2 of LIPT2 gene on chromosome-11, resulting in amino acid substitution of serine for arginine at codon 158, suggestive of lipoyl (octanoyl) transferase-2 (LIPT2) deficiency. On follow-up at 6 years of age, she has intermittent generalized seizures, inability to walk independently, and language delay.Figure 1: a-d: (a) Axial noncontrast computed tomography scan shows bilateral basal ganglia calcification. Coronal T2w (b) and axial FLAIR (c and d) images show volume loss in the corpus callosum, cystic changes in the periventricular region (black arrows), and cone-shaped hyperintensity at the frontal periventricular rim in the region of forceps minor (arrowheads) mimicking ‘Ears of the Lynx’‘Ears of the Lynx’ sign was first described by Riverol et al.[1] in 2009 in spastic paraplegia-11 (SPG11) due to SPG11 gene mutation. This sign is associated with SPG11 and SPG15, with a sensitivity of 78.8–98% and a specificity of 90–100%.[2] It is due to T1 hypointensity and T2/FLAIR hypointensity of the forceps minor region (genu fibers) of corpus callosum, resembling crowning tufts of hair on the tips of the lynx’s ears.[2–4] The ‘Ears of the Lynx’ sign has also been reported in Marchiafava–Bignami disease.[4] Basal ganglia calcification has been reported in LIPT2 deficiency.[3] LIPT2-associated defects may cause severe neonatal encephalopathy and brain abnormalities.[3] We illustrate the first ‘Ears of the Lynx’ sign observed in a mitochondrial lipoylation defect. Declaration of informed consent Written informed consent obtained from the parents. Ethical publication statement We confirm that we have read the Journal’s position on issues involved in ethical publication and affirm that this report is consistent with those guidelines. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.