3MC Syndrome 1
Autosomal recessive
3MC syndrome 1 is caused by changes in both copies of MASP1, a gene in the lectin complement pathway that also guides the movement of cells that shape the face during early development. Each parent usually carries one changed copy.
Signs and symptoms
Widely spaced eyes, droopy eyelids, highly arched eyebrows and cleft lip and/or palate are the most typical features, often with slow growth after birth. Learning difficulties or intellectual disability and hearing loss are common. Less often there is early fusion of skull bones (craniosynostosis), fused forearm bones, an umbilical hernia or other abdominal wall defect, and kidney, bladder or genital differences.
What a diagnosis changes
Care is coordinated around the features present, with cleft and craniofacial surgery, hearing and eye assessment, kidney and urinary tract imaging, and developmental and educational support. Genetic counselling is recommended; parents are usually carriers, each future child has a 1 in 4 chance of being affected, and carrier testing can be offered to relatives.
Genes analysed
Also known as
3MC syndrome caused by mutation in MASP1; 3MC syndrome type 1; 3MC1; MASP1 3MC syndrome; Michels syndrome
