Meckel syndrome 1 / Bardet-Biedl Syndrome 13 (MKS1)
MKS1-associated ciliopathies include two overlapping disorders, known as Bardet-Biedl syndrome and Meckel syndrome. Both diseases are inherited in an autosomal recessive manner, manifest at birth, and can be caused by pathogenic variants in the gene MKS1. While MKS1-associated ciliopathies are found in individuals of different ethnicities, they are more commonly diagnosed in individuals of Finnish descent, due to the presence of a founder mutation. Bardet-Biedl syndrome is characterized by obesity, intellectual disability, kidney disease, polydactyly, and loss of vision that begins with loss of night vision and progresses to tunnel vision and blindness. Meckel syndrome, which is more severe, often manifests before birth. Infants are often born with a neural tube defect called occipital encephalocele, brain malformations, facial dysmorphism, renal agenesis, and extra digits. Life expectancy varies according to the phenotype; for many patients with Bardet-Biedl syndrome, it may only be reduced for those with a more severe phenotype, but death in infancy is expected in patients with Meckel syndrome. Currently, it is not possible to predict which phenotype a patient will have based on the inherited variants.
For information about carrier frequency and residual risk, please see the residual risk table.