Autosomal recessive
Caused by changes in both copies of the NANS gene, which makes an enzyme in the production of sialic acid. Reduced enzyme activity leads to raised levels of N-acetylmannosamine (ManNAc) in urine.
Signs and symptoms
Short stature with short limbs and skeletal changes affecting the spine and the growing ends of long bones. Developmental delay and intellectual disability are typical, and facial differences were seen in all nine patients in one cohort. Seizures and gastrointestinal problems have also been reported.
What a diagnosis changes
Developmental and educational support, growth and orthopaedic monitoring, and seizure management if needed. Parents of an affected child are usually both carriers, so genetic counselling and carrier testing can be offered.
Genes analysed
Also known as
SEMD Genevieve type; SEMD, Geneviève type; SEMDG; spondyloepimetaphyseal dysplasia, Camera-Genevieve type
