Clinical Characteristics

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.