Borderline normal intelligence in the Smith-Lemli-Opitz (RSH) syndrome

Area of Science:

• Genetics
• Developmental Biology
• Metabolic Disorders

Background:

• Smith-Lemli-Opitz (RSH) syndrome is an autosomal recessive disorder.
• It is characterized by intellectual disability and distinctive facial features.
• Previous reports predominantly documented severe to profound cognitive impairment.

Observation:

• Two siblings with RSH syndrome were identified.
• One sibling presented with the full spectrum of RSH syndrome features.
• The other sibling exhibited a milder phenotype, including borderline normal intelligence.

Findings:

• This case series demonstrates significant phenotypic variability in RSH syndrome.
• Intellectual disability in RSH syndrome may range from profound to borderline normal.
• The autosomal recessive inheritance pattern allows for variable expression.

Implications:

• RSH syndrome diagnosis should be considered even in individuals with milder cognitive impairments.
• Understanding phenotypic variability is crucial for accurate diagnosis and genetic counseling.
• Further research is needed to elucidate the genetic and environmental factors influencing RSH syndrome expression.