This condition is caused by changes in both copies of a gene called RPS6KC1. It can vary a lot in how severe it is. In some cases, it leads to loss of the pregnancy before birth. In others, people survive but have a complex condition that mainly affects brain development.
Main features of the condition:
• Development and learning:Almost all affected children have delays in development and learning difficulties. These can be mild or severe. Some children may lose skills they had already learned as they get older.
• Movement and muscle tone:Babies are often “floppy” at birth (low muscle tone). Over time, this can change into stiffness and weakness, especially in the legs or all four limbs. Reflexes are often increased, and there may be nerve problems affecting the arms and legs.
• Behavior:Many children have behavioral differences, such as autistic traits, anxiety, repetitive behaviors, ADHD, and sometimes aggression or low mood.
• Movement disorders: Some develop problems like unsteady walking, tremors, abnormal muscle contractions (dystonia), or sudden jerks (myoclonus).
• Seizures: More than half of affected individuals have seizures.
• Before birth: The condition is linked to a higher risk of miscarriage, stillbirth, or severe fetal swelling (hydrops).
• Facial features:Many children share certain facial characteristics, such as:
o Long face and prominent forehead
o Eyes that slant downward or droopy eyelids
o Eyes set closer together than usual
o Prominent nose and long groove between nose and lip
o Thin upper lip
o Dental differences (for example, prominent front teeth)
o Low-set or rotated ears and a small lower jaw
• Bones and muscles: Common findings include curvature of the spine (scoliosis), exaggerated lower back curve, high-arched feet, and a generally thin body build.
• Other features:Eye movement problems (like strabismus or difficulty initiating eye movements) and heart issues such as mitral valve prolapse can occur.
Brain imaging findings (MRI):
• Less white matter in the brain than usual
• Slower development of the brain’s insulating layer (myelin) in infancy
• A thinner or underdeveloped structure connecting the two brain halves (corpus callosum)
• Enlargement of certain brain spaces (colpocephaly)
• General brain shrinkage (atrophy)
• Underdevelopment of parts of the cerebellum and brainstem, and sometimes a larger-than-normal fluid space at the back of the brain
RPS6KC1