Complex strabismus in a patient with KBG syndrome with 16q24.3 microdeletion
Hee Kyung Yang1, Anna Cho2, Jae Hyoung Kim3
1Department of Ophthalmology, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam, Korea.
Insights
This case study details a 5-year-old boy with KBG syndrome and a 16q24.3 microdeletion who presented with complex strabismus. The findings highlight the ophthalmologic manifestations associated with this rare genetic disorder.
Area of Science:
- Genetics
- Ophthalmology
- Pediatrics
Background:
- KBG syndrome is a rare genetic disorder characterized by intellectual disability, craniofacial, and skeletal abnormalities.
- The 16q24.3 microdeletion is a specific genetic cause associated with KBG syndrome.
Observation:
- A 5-year-old boy with KBG syndrome and 16q24.3 microdeletion presented with complex strabismus, including left esotropia and ptosis.
- Additional findings included submucosal cleft palate, velopharyngeal insufficiency, prominent eyebrows, short fifth fingers, and fetal finger pads.
- Ophthalmologic examination revealed bilateral upgaze limitation and mild downgaze limitation, with significant left esotropia and hypotropia.
Findings:
- Neurological and ophthalmologic investigations, including MRI, were normal, ruling out structural abnormalities of the orbit and cranial nerves.
- Negative results for anti-acetylcholine receptor antibody, ice test, thyroid function, and repetitive nerve stimulation tests excluded common causes of ptosis and strabismus.
Implications:
- This case highlights the potential for complex strabismus and ocular motility disorders in individuals with KBG syndrome and 16q24.3 microdeletion.
- Further research is warranted to understand the spectrum of ophthalmologic manifestations in KBG syndrome and guide clinical management.
Abstract:
KBG syndrome is characterized by intellectual disability, and craniofacial and skeletal abnormalities. We report the case of a 5-year-old boy with KBG syndrome with 16q24.3 microdeletion who showed complex strabismus. Left esotropia and ptosis was first noticed by parents at 18 months of age. He also showed submucosal cleft palate, velopharyngeal insufficiency, prominent eyebrows, short fifth fingers, and fetal finger pad. Marginal reflex distances were +4 mm in the right eye and +1.5 mm in the left eye. He had 18Δ of left esotropia, and 12Δ of left hypotropia, which increased with head tilt to the right. Ductions and versions showed bilateral upgaze limitation, more on the right eye, and mild limitation of downgaze on adduction in both eyes. Anti-acetylcholine receptor antibody test, ice test, thyroid function test and the repetitive nerve stimulation test were all negative. Magnetic resonance imaging revealed normal orbital structures, including the bony orbit, oculomotor, trochlear, and abducens nerves, and extraocular muscles in both eyes.
