CSS is characterized by distinctive abnormalities of the head and facial (craniofacial) region with affected individuals often described as having coarse facial features that become more prominent with age. Affected individuals may have an unusually small or Large head (micro- or macrocephaly); a wide mouth with full, prominent lips; a broad nasal tip; a low nasal bridge; and an abnormally long vertical groove between the nose and the upper lip (philtrum). Additional features may include thick eyebrows, long eyelashes, and generalized excessive hair growth (hypertrichosis) with the exception of the scalp hair, which tends to be relatively sparse (scalp hypotrichosis). Reports suggest that sparse scalp hair improves with age.
Individuals with CSS also have characteristic skeletal abnormalities. For example, certain fingers and toes (digits), particularly the fifth fingers (“pinkies”) and toes, may be unusually short due to absence or underdevelopment (hypoplasia) of the end bones (terminal phalanges) within these digits. The fingernails and toenails may also be underdeveloped or absent. Additional abnormalities may include dislocation of the inner forearm bone (radius) at the elbow, deformity of the hip (coxa valga), or unusually small or absent knee caps (patellae). However, there are individuals with CSS who do not have the classic fifth digit findings.
Early in life, infants with CSS typically experience feeding difficulties, vomiting, Slow growth and weight gain (failure to thrive) which may have begun while the infant was still in the womb (intrauterine growth retardation), and frequent respiratory infections. In addition, affected infants and children may have hypotonia, abnormally loose joints, delayed bone age (2 to 3 years behind the chronological age), and mild to severe intellectual disability. Affected infants and children may also have mild to severe speech delays, where expressive language is affected more severely than receptive language, as well as moderate to severe delays in motor skills such as sitting and walking. Reports suggest that on average, affected children learn to sit up at 12 months (typically occurs at 6 to 8 months), walk at 30 months (typically occurs at 9 to 18 months), and speak at 24 months (typically begins around 12 months).
Affected individuals may also have eye (ophthamologic) abnormalities. This can include drooping of the upper eyelid (ptosis), clouding of the lens of the eye (cataracts), and misalignment of the eyes (strabismus, commonly known as “lazy eye”).
CSS has been reported to manifest kidney (renal) or genitourinary abnormalities in some affected individuals. There have been reports of affected individuals with fused kidneys at the lower end (horseshoe kidney) and the urethra – the tube through which urine drains from the bladder to exit the body – opening on the underside of the penis instead of at the tip (hypospadias).
Individuals with CSS may also have gastric abnormalities which may include one portion of the bowel sliding into the next like a telescope (intussusception) or an opening in the diaphragm allowing abdominal organs to push up into the chest cavity (diaphragmatic hernia).
Less commonly, affected individuals may have additional physical abnormalities, such as choanal atresia, a malformation in which a bony or thin layer of tissue blocks the passageway between the nose and throat, leading to Breathing difficulties. Some individuals with CSS may also have heart abnormalities at birth. In addition, a brain abnormality known as Dandy-Walker malformation has been reported in some cases. This condition is characterized by cystic malformation and expansion of one of the cavities in the brain (fourth ventricle). Dandy-Walker malformation is usually associated with an abnormal accumulation of cerebrospinal fluid (CSF) in the skull (hydrocephalus), resulting in increased fluid pressure, a rapid increase in head size, abnormal prominence of the back region of the head (occiput), and/or other associated findings. Some individuals with CSS may also have partial or complete absence of the band of nerve fibers that joins the two hemispheres of the brain (agenesis of the corpus callosum) and fewer folds in their brain (gyral simplification). Some affected individuals may also experience hearing loss, Seizures and tics. There have been reports of liver cancer (hepatoblastoma) in affected individuals, but the link between CSS and tumor risk needs to be further investigated.