Phenotypic Variation between Monochorionic Diamniotic Twins with Coffin-Siris Syndrome

Area of Science:

• Medical Genetics
• Reproductive Medicine
• Developmental Biology

Background:

• Coffin-Siris syndrome (CSS) is a rare genetic disorder characterized by intellectual disability, facial anomalies, and growth deficiencies.
• Monochorionic-diamniotic (MCDA) twins share a placenta and amniotic sac, presenting unique developmental and clinical challenges.
• Genetic variations in genes like ARID1B are commonly associated with Coffin-Siris syndrome.

Observation:

• The study presents the first documented case of MCDA twins diagnosed with Coffin-Siris syndrome.
• Despite identical genomes and causative variants, the twins exhibited significant phenotypic discordance.
• Early diagnosis was achieved through advanced precision medicine techniques.

Findings:

• The case demonstrates that even with identical genetic makeup, significant phenotypic variability can occur in Coffin-Siris syndrome within MCDA twins.
• Precision medicine approaches enabled timely diagnosis and intervention, influencing clinical outcomes.
• This case expands the understanding of CSS presentation and genetic expression in a twin context.

Implications:

• Highlights the complex interplay between genetics and epigenetics in determining phenotype, even in identical twins.
• Underscores the importance of early diagnosis and tailored interventions in managing Coffin-Siris syndrome.
• Provides valuable insights for reproductive medicine specialists and genetic counselors managing high-risk twin pregnancies.