Pilarowski–Bjornsson Syndrome with Congenital Heart Defect: A Case Report and Literature Review
Introduction Pilarowski–Bjornsson syndrome (PILBOS) is a rare autosomal dominant neurodevelopmental disorder caused by heterozygous variants in chromodomain helicase DNA-binding protein 1 (CHD1), a gene encoding an adenosine triphosphate (ATP)-dependent chromatin remodeler. Since its initial description in 2018, only…
2026 1,330 reads 0 citations
Case Reports
Pilarowski–Bjornsson Syndrome with Congenital Heart Defect: A Case Report and Literature Review
IntroductionPilarowski–Bjornsson syndrome (PILBOS) is a rare autosomal dominant neurodevelopmental disorder caused by heterozygous variants in chromodomain helicase DNA-binding protein 1 (CHD1), a gene encoding an adenosine triphosphate (ATP)-dependent chromatin remodeler. Since its initial description in 2018, only a limited number of cases have been reported in the literature.
Case PresentationA 4-month-old male infant presented with persistent hypotonia and recurrent focal seizures beginning in the neonatal period, accompanied by severe global developmental delay. Brain magnetic resonance imaging (MRI) was structurally normal. Whole exome sequencing identified a heterozygous de novo CHD1 variant (NM_001270.4: c.797C>T; p.Pro266Leu), classified as a variant of uncertain significance. Echocardiography revealed a medium-sized secundum atrial septal defect with right-sided chamber dilatation. The clinical course was complicated by recurrent lower respiratory tract infections and progressive respiratory distress.
Literature ReviewReview of eight previously reported cases confirms global developmental delay and hypotonia as universal features of PILBOS (8/8, 100%). Dysmorphic craniofacial findings were present in 7/8 (87.5%) cases, and seizures occurred in 3/8 (37.5%). Intellectual disability was confirmed in 3/8 (37.5%) and not assessable in a further 3/8 (37.5%). Respiratory complications were documented in 1/8 (12.5%) cases. De novo inheritance was confirmed in 4/8 (50%) cases. No structural cardiac defects have been documented in any previously reported case, and all 8/8 (100%) patients were alive at last follow-up.
ConclusionFindings from this case suggest that structural congenital heart defects may represent an underrecognized component of the PILBOS phenotypic spectrum. Further case reports and functional investigations are required to establish whether cardiac involvement constitutes a consistent feature of CHD1-related disease.
Keywords Chromodomain helicase DNA-binding Proteins Neurodevelopmental disorders Atrial septal defect Exome sequencing All subjects
Barw Medical Journal. 2026;4(1):55–59