Clinical Characteristics

In dominant STT3A-CDG the main clinical features are:
Skeletal abnormalities – 10/16
Intellectual disability – 9/13 (3 unreported)
Short stature – 8/16
Macrocephaly – 6/16
Increased muscle tone 5/15 (1 unreported)
Early onset arthritis 4/15 (1 unreported)
Inverted nipples – 4/16
Abnormal fat distribution – 3/16
Intra uterine growth restriction – 2/16
Hypotonia – 2/15 (1 unreported)

Other features only described in single individuals can be found in Wilson et al. (2021).

Out of the ten individuals with skeletal abnormalities, three had mild metaphyseal flaring (in one affected individual in combination with epiphyseal abnormalities), two had vertebral abnormalities, and one had tibial and ulnar epiphyseal deformity and scoliosis. Three children had a (late closing) large anterior fontanel.

All individuals showed a type 1 serum transferrin glycosylation profile. Other laboratory abnormalities were uncommon. Transaminase levels were normal. Decreased coagulation factors were detected in two individuals. Decreased testosterone levels were present in one child, and increased thyroid-stimulating hormone (TSH) level in another child, without clinical symptoms of hypothyroidism. Delayed puberty was detected in two patients.

In autosomal recessive STT3A-CDG the main clinical features were as follows:

Shrimal et al. (2013) reported neurologic abnormalities including hypotonia, microcephaly, seizures, severe developmental delay, intellectual disability, failure to thrive and feeding problems in 2 individuals from one family.

Ghosh et al. (2017) reported severe developmental delay, intellectual disability, microcephaly and seizures in 5 individuals from a single family. Two individuals also developed episodic hypothermia and decreased consciousness.

Chang et al. (2019) described developmental delay and seizures alongside chronically low factor VIII and von Willebrand factor levels in one affected individual.