short stature

The facies are sometimes described as 'bird-like' with a beaked nose, brachycephaly, and micrognathia.  Microstomia with a shortened ramus and forward displacement of the termporomandibular joints is characteristic. Upper airway obstruction may occur with severe respiratory distress.  The forehead is relatively prominent, the palate is highly arched, and the teeth are often small and some may be missing with misalignment of others.  A few teeth may even be present at birth (natal teeth).  Children appear petite and are often short in stature.  Scalp hair is thin, especially in the frontal and occipital areas, and the skin is atrophic.  Developmental delays are common but most patients have normal or near-normal intelligence.

The facial features are considered to be distinctive, characterized by a broad, square face, prominent forehead, broad nasal bridge, and midface hypoplasia.  These and other features appear more pronounced with age as in the size of the jaw which is underdeveloped in infancy and eventually becomes prognathic.  Most patients have developmental delays, speech and motor deficits, cognitive impairments and behavioral abnormalities.  Hypotonia, hyporeflexia, failure to thrive, lethargy, and feeding difficulties are common in infants.  Older individuals have REM sleep disturbances with self-destructive behaviors, aggression, inattention, hyperactivity, and impulsivity.  Short stature, hypodontia, brachydactyly, hearing loss, laryngeal anomalies, and peripheral neuropathy are common. Seizures are uncommon.

The behavioral profile of this syndrome can resemble that of autism spectrum disorders although symptoms of compulsivity are more mild.

A related developmental disorder known as Potacki-Lupski syndrome (610883) involving the same locus on chromosome 17 has a similar behavioral profile.  Ocular and systemic malformations may be less severe though.

This is a syndrome of multiple congenital anomalies.  Among these are dwarfism, micrognathia, hard palate anomalies, hypotonia, anomalies of the external genitalia, polysyndactyly, microcephaly, and mental retardation.  It has been suggested that many individuals have a characteristic behavioral profile consisting of cognitive delays, hyperreactivity, irritability, language deficiency, and autism spectrum behaviors.  Some individuals exhibit aspects of self destructive behavior.  Tissue levels of cholesterol are low.

This disorder has a wide variety of clinical features and many occur in only a few patients.  The skin has focal areas of hypoplasia with hypopigmentation, often appearing in a streak or linear pattern.  These areas may be present at birth and contain bullae or urticarial lesions with signs of inflammation.  Telangiectases and herniated fat may appear in these areas.   Oral, esophageal, and laryngeal fibrovascular papillomas occur but they may also be seen in the perineal, vulvar, and perianal areas.  These may be large, friable, and recurrent.  The teeth erupt late and are usually hypoplastic.  The nails are often dysplastic and the hands and feet may be 'split' with syndactyly of the third and fourth fingers giving a 'lobster claw' appearance.  Polydactyly may be present.  Most have thin 'protruding' ears.  A variety of skeletal anomalies have been reported including absence of metatarsals and metacarpals.  A considerable number of patients have mild to moderate mental deficits.  Severely affected females may die in infancy.

Non-ocular features include cerebellar atrophy, psychomotor developmental delays, mental retardation, and muscle weakness.  Dysarthria is common.  The myopathy has its onset in childhood and is progressive with weakness, hypotonia, and atrophy eventually leading to total disability in some cases.  Progression of motor dysfunction may, however, stabilize in some patients but at an unpredictable level.  Infants are often 'floppy babies'.  MRI studies reveal cerebellar atrophy.  Serum creatine kinase levels are increased and muscle biopsies show chronic myopathic changes.  Skeletal features include short stature, pectus carinatum, and secondary kyphoscoliosis and foot deformities.  Bone abnormalities may be seen in the digits.

The neuropathy is primarily motor and usually begins in the lower extremities but is progressive and eventually involves the arms as well.  Motor development is slow and walking is often unsteady from the start.  Speaking may not have its onset until 3 years of age.   Mild, nonprogresssive cognitive defects and mental retardation are often present.  Sensory neuropathy with numbness and tingling develops in the second decade.  Mild chorea, upper limb tremor, mild ataxia, and extensor plantar responses may be seen.  Deafness has been described.  Nerve conduction studies and biopsies have documented a demyelinating polyneuropathy while MRIs demonstrate cerebral and spinal cord atrophy which may be seen in the first decade of life.  The MRI in many patients reveals diffuse cerebral atrophy, enlargement of the lateral ventricles and focal lesions in subcortical white matter.  Most individuals have mild cognitive deficits while psychometric testing reveals borderline intelligence in a minority.

Patients are susceptible to acute rhabdomyolysis following viral infections.  Most are severely disabled by the third decade.

The facial dysmorphism appears in childhood and consists of a prominent midface, hypognathism, protruding teeth, and thickening of the lips.  Spinal deformities occur in the majority of individuals along with foot and hand claw deformities.  All patients are short in stature.  Hypogonadotropic hypogonadism is a common feature and females may be infertile.  Amenorrhea is often present by the age of 25-35 years.

This is a clinically heterogeneous disorder.  Skin atrophy with pigmentary changes, telangiectasia, short stature, premature aging, and skeletal abnormalities are characteristic.  There is an increased risk of malignancy, particularly osteosarcomas and skin cancer.  Saddle nose, sparse hair, hypogonadism, dysplastic nails, and teeth anomalies have also been described.

The skin is usually normal at birth but an erythematous rash typically appears in the first six months of life accompanied by swelling and blistering.  Eventually areas of hypo- and hyperpigmentation appear in a reticulated pattern with spots of punctate atrophy and telangiectasia.  Hyperkeratosis of the soles of the feet is common.  The skeletal abnormalities of dysplasia, radial ray defects, and missing bones are often evident at birth while osteopenia and delayed bone maturation are evident later.

Hypotonia, lax joints, midface hypoplasia, prominent forehead, and short stature have been described.  Some, but not all patients have a degree of psychomotor retardation.  Mild hearing impairment has been reported.