CTNNB1 Syndrome with Spinal Lipoma: A Case Report Highlighting Medullary Involvement

We present a 7-year-old girl, born to non-consanguineous healthy parents, who was diagnosed with severe intrauterine growth restriction (IUGR) in the third trimester of pregnancy. She exhibited the first symptoms at 4 months of age, with microcephaly (5th percentile) and hypotonia. On physical examination at 22 months, she showed progressive microcephaly (<P1), a broad nose with a bulbous tip, full eyelids, convergent strabismus, and generalized hypotonia with hypertonia of the lower limbs. Initially, an array-CGH study and cranial MRI were performed, both yielding normal results. Whole exome sequencing identified a de novo, likely pathogenic heterozygous variant in the CTNNB1 gene (c.881T>A, p.L294*). Currently, at 7 years of age, she has intellectual disability, global speech delay (though she can form simple sentences and maintain basic conversation), spastic diplegia, spinal tethering signs with a conus at the level of L3-L4 related to a filum lipoma (IV C), mild ependymal duct dilation, and neurogenic bladder.
In summary, this patient presents the typical clinical features described in individuals with CTNNB1 syndrome. Regarding language development, she shows a better outcome than expected. We emphasize the importance of performing spinal MRI, as medullary abnormalities such as lipomas have also been reported in other patients, similar to the present case.