Simpson-Golabi-Behmel syndrome type 1 with normal birth parameters

Area of Science:

• Medical Genetics
• Pediatric Endocrinology
• Prenatal Diagnosis

Background:

• Simpson-Golabi-Behmel syndrome (SGBS) is a rare genetic overgrowth disorder characterized by distinctive facial features, intellectual disability, and organ anomalies.
• Early and accurate diagnosis is crucial for appropriate management and genetic counseling.

Observation:

• A preterm infant presented with prematurity, dysmorphic features, and congenital heart defects, with antenatal scans revealing macrosomia and specific organ abnormalities.
• Initial antenatal genetic tests for overgrowth syndromes were negative, and the infant had normal birth parameters, complicating the clinical suspicion.
• Manual inspection of trio whole exome sequencing raw data from an amniocentesis sample identified a hemizygous exon 7 deletion in the GPC3 gene.

Findings:

• The GPC3 gene deletion confirmed a postnatal diagnosis of Simpson-Golabi-Behmel syndrome.
• This case highlights an atypical presentation of SGBS, challenging initial diagnostic assumptions.
• Obstacles in diagnostic genetic testing, including the need for raw data re-analysis, were encountered.

Implications:

• This case underscores the importance of considering rare genetic syndromes even with atypical presentations and normal birth parameters.
• It emphasizes the value of thorough review of genetic sequencing data, including raw data, for uncovering complex genetic variations.
• Improved diagnostic strategies are needed for rare overgrowth syndromes like SGBS, particularly in the prenatal and neonatal periods.