low-set ears

This is a severe congenital neurodevelopmental disorder with global delay, hypotonia, and characteristic facies.  It is usually present at birth and soon manifest as a profound intellectual delay.  Most patients do not develop speech or independent motor skills.  Feeding difficulties are evident early and often require gastric tube placement for nutrition.  Failure to thrive is common.   Most patients have seizures of a tonic-clonic or atonic type which may be controlled with medication. 

Microcephaly, brachycephaly, plagiocephaly, and brachycephaly have been described.  A high forehead with frontal bossing, facial hypotonia, triangular facies have been described.  The ears are low-set and posteriorly rotated.  The upper lip is often thin and the mouth is commonly open.  The neck appears short, the nose is bulbous while the nasal bridge is prominent and the nares may be anteverted.

Brain imaging is normal in some patients but there is evidence of generalized cerebral atrophy, with a thin corpus callosum and decreased myelination in others.  Variable features such as scoliosis, hip contractures, muscle wasting, and dyskinesias are sometimes seen.

Multiple anomalies and malformations were present in the two reported patients, an unrelated male and female.  Severe facial dysmorphism secondary to uneven skull bone formation and suture closures is present.  The metopic ridge is prominent, the orbital bones are deficient, the occiput is flattened, the anterior fontanel and coronal sutures are wide.  Midfacial hypoplasia is present.  The neck is broad and the shoulders are narrow.  The fingers are long and the distal phalanges may be fixed in flexion.  The ears are low-set, small, and cupped.  The palate is high and may be cleft.  Cutaneous syndactyly of the fingers has been observed.  Variable developmental delays/learning difficulties are present.

The male had an imperforate anus, undescended testes and a 60 dB hearing loss.  The female had a midline cleft palate with choanal atresia requiring a tracheostomy from birth and required fundoplication and gastrostomy for gastroesophageal reflux.

The phenotype is somewhat variable.  Intrauterine and postnatal growth retardation with hypotonia are common.   Moderate to severe intellectual disability is usually present and speech may be severely delayed.  The forehead is narrow, the nasal tip is broad, the nasal bridge is depressed, and the ears are low-set and posteriorly rotated.   Small hands and sometimes joint laxity are commonly present.  Cervical spine abnormalities including clefting, improper fusion, and segmentation anomalies are common.

Brain MRI may be normal but a small corpus callosum was present in some patients.

Low-set simple ears were noted in two stillborn fetuses.  Micrognathia and a broad and beaked nose with notched alae nasi were described together with a malformed and atretic larynx.  The fingers and toes may be short and cutaneous syndactyly may be present.  The position of the anus may be abnormal.  The lungs may have abnormal lobulation and appear hyperplastic and hyperechogenic.  The bladder and kidneys may be absent.

The phenotype is heterogeneous and not all patients have all features.  The facial features are said to resemble those of the Down syndrome with brachycephaly, a high forehead, and a flat midface with shallow orbits and malar hypoplasia.  The ears are small, low-set, and posteriorly rotated.  The nose is short and the nasal bridge is broad and flat.  The mouth is small and the upper lip is thin.  The scalp hair may be sparse and the nails sometimes appear dystrophic.

The fingers are sometimes brachydactylous and tapered.  Short stature is common and the joints may have limited motion.  Dislocation of the radial heads is seen rarely while radioulnar synostosis has been seen in a few individuals.  Postnatal short stature is common.

Seizures often occur.  The ventricles appear large and cerebral atrophy has been reported.  Intellectual disability and mental retardation are common. However, at least one individual attended university although he had been diagnosed in childhood with Asberger disease.   Neurosensory hearing loss is common.

ZTTK syndrome is multisystem malformation and developmental disorder with a heterogeneous clinical presentation.  The facial features might suggest the diagnosis at birth but most of the signs are nonspecific including frontal bossing, underdevelopment of the midface, facial asymmetry, low-set ears, broad and/or depressed nasal bridge, and a short philtrum.  Poor feeding and hypotonia in the neonatal period are usually present and physical growth is subnormal resulting in short stature.

Brain imaging may show abnormal gyral patterns, ventriculomegaly, hypoplasia of the corpus callosum, cerebellar hypoplasia, arachnoid cysts, and loss of periventricular white matter.  About half of patients develop seizures and many have intellectual disabilities.  Spinal anomalies include hemivertebrae with scoliosis and/or kyphosis.  Other skeletal features include joint laxity in some patients and contractures in others.  Arachnodactyly, craniosynostosis, and rib anomalies have been reported.  There may be malformations in the GI, GU, and cardiac systems while immune and coagulation abnormalities have also been reported.