The most typical features of Schaaf-Yang syndrome include:
- Developmental delay (a delay in reaching developmental milestons, such as sitting up, crawling, walking, talking, and others
- Intellectual disability (possibly requiring special education)
- Hypotonia (low muscle tone, in neonates and infants also referred to “floppy baby” syndrome)
- Contractures of the hands (fingers appear tightly gripped, turned in another direction, may overlap, or may curve)
- Feeding difficulties (usually requiring assistance in feeding or tube feeding)
Other common features include:
- Eye abnormalities (near or far sighted, “crossed” eye)
- Hypogonadism (undescended testes, small penis, abnormal vaginal size/shape, etc.)
- Small hands and/or feet
- Sleep apnea, obstructive or central (breath holding spells during sleep)
- Decreased fetal movement (meaning a reduced amount of movement from the child during pregnancy)
- Gastroesophageal reflux (GERD, spitting up, acid reflux, etc.)
Some common behavioral features include:
- Autism (formal diagnosis of autism spectrum disorder or signs/symptoms of autism)
- Behavior problems (impulsive, compulsive, stubborn, manipulative)
- Skin picking or self injury
In some cases, other symptoms are observed and should not be discounted.
As well, some individuals expressing a specific mutation show more severe symptoms during pregnancy that can be fatal. Identifying this mutation is critical for further family counselling.