SG01 Generalized hypertrichosis without developmental delay in FHEIG syndrome secondary to KCNK4 mutation

Abstract

FHEIG syndrome is a rare neurodevelopmental syndrome characterized by facial dysmorphism, hypertrichosis, epilepsy, intellectual disability/developmental delay and gingival overgrowth. It is caused by de novo mutations in the KCNK4 gene. Irregular activation or inhibition of K+ currents traversing the plasma membrane of cells lead to changes in neurotransmission, cardiac arrhythmias, endocrine dysfunction and developmental disruption including of hair follicles. We present a case of generalized hypertrichosis in a 12-month-old girl of Irish descent with no significant family history and no developmental concerns. The first-born child, she had normal lanugo hair at birth, but then subsequently developed very long terminal hairs on her limbs and trunk. Examination demonstrated extensive hypertrichosis on her limbs and trunk, with normal eyelashes and normal scalp hair. There was subtle dysmorphism evident with vertical ridging of the nasal tip. Trio-exome sequencing revealed a de novo variant in KCNK4. She was referred to neurology and oral medicine in light of the diagnosis, and was subsequently diagnosed with epilepsy and gingival hyperplasia, but she continues to meet her age-­appropriate developmental milestones. This highlights a rare case of hypertrichosis secondary to de novo KCNK4 mutation, without the intellectual disability or developmental delays that typically result from the channelopathy.