3MC syndrome
3MC syndrome is a rare genetic disorder characterized by distinctive facial features, developmental delays, and abnormalities affecting various tissues and organs.
Overview
3MC syndrome is a disorder characterized by unusual facial features and problems affecting other tissues and organs. It encompasses four disorders that were formerly considered to be separate: Mingarelli, Malpeuch, Michels, and Carnevale syndromes. Researchers now generally consider these disorders to be part of the same condition, which is called 3MC based on the initials of the older condition names.
Symptoms
The distinctive facial features of people with 3MC syndrome include:
- Widely spaced eyes
- A narrowing of the eye opening
- Droopy eyelids
- An opening in the upper lip with an opening in the roof of the mouth
Other common features include:
- Developmental delay
- Intellectual disability
- Hearing loss
- Slow growth after birth resulting in short stature
Less often, individuals may have:
- Abnormal fusion of certain bones in the skull (craniosynostosis) or forearm (radioulnar synostosis)
- An outgrowth of the tailbone (caudal appendage)
- A soft out-pouching around the belly-button (an umbilical hernia)
- Abnormalities of the kidneys, bladder, or genitals
Causes
3MC syndrome is caused by mutations in the COLEC10, COLEC11, or MASP1 gene. These genes provide instructions for making proteins involved in the lectin complement pathway. This pathway helps direct the migration of cells during development before birth, particularly neural crest cells, which give rise to tissues in the face, skull, endocrine glands, and nervous system. After birth, this pathway is involved in the immune system.
Mutations impair or eliminate the function of these proteins, leading to faulty control of cell migration. Researchers suggest that similar pathways in the immune system can compensate for these problems, which explains why immune system abnormalities are not typically part of 3MC syndrome.
Genes associated with 3MC syndrome
- COLEC10
- COLEC11
- MASP1
Inheritance
This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.