dwarfism

Gracile Bone Dysplasia

Clinical Characteristics
Ocular Features: 

The eyes have been described as small.  Aniridia may be present.

Systemic Features: 

This is a usually fatal form of skeletal dysplasia with splenic and ocular features as well.  In utero death is not uncommon while newborns may not survive the neonatal period.  The face has been described as dysmorphic with a high forehead, flat nasal bridge, a cloverleaf-shaped skull, and hypoplastic cranial bones with premature suture closure.  The long bones are dysplastic as well with thinned diaphyses (sometimes fractured in utero), growth plate disorganization, excessive remodeling, and signs of arrested growth.  The ribs share in the dysplasia but pulmonary hypoplasia has also been described.  Most individuals have short limbs.

The spleen can be hypoplastic or aplastic and ascites has been noted in several infants.  Failure to thrive is common and seizures have been reported.  Males may have micropenis and hypospadias while females have been described with labial fusion.  

Low parathyroid hormone levels and hypocalcemia has been reported in most individuals.

Genetics

Heterozygous mutations in the FAM111A gene (11q12.1) have been associated with this disorder.  The functional role of FAM111A products is unknown but likely play a role in calcium metabolism, parathyroid hormone secretion, and osseous development.

Mutations in the same gene can be responsible for the allelic autosomal dominant Kenny-Caffey syndrome (127000) with some similar features.

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

No treatment has been reported.

References
Article Title: 

FAM111A mutations result in hypoparathyroidism and impaired skeletal development

Unger S, Gorna MW, Le Bechec A, Do Vale-Pereira S, Bedeschi MF, Geiberger S, Grigelioniene G, Horemuzova E, Lalatta F, Lausch E, Magnani C, Nampoothiri S, Nishimura G, Petrella D, Rojas-Ringeling F, Utsunomiya A, Zabel B, Pradervand S, Harshman K, Campos-Xavier B, Bonafe L, Superti-Furga G, Stevenson B, Superti-Furga A. FAM111A mutations result in hypoparathyroidism and impaired skeletal development. Am J Hum Genet. 2013 Jun 6;92(6):990-5.

PubMed ID: 
23684011

Spherophakia and Metaphyseal Dysplasia

Clinical Characteristics
Ocular Features: 

The corneas and anterior chambers were normal in the son but the lenses were small and spherical and had colobomatous defects.  The father developed a retinal detachment in one eye and elevated intraocular pressure. The morphology of the lenses in the father is unknown.

Systemic Features: 

The diaphyses of the long bones are thickened with relative sparing of the small bones in the extremities.  The epiphyses become more irregular later in life.  The vertebrae are deformed with flattening.  The result is brachymelia and moderately severe dwarfism.  Pigeon breast deformity can be present.

Genetics

A father and son have been reported with this combination of findings suggesting autosomal dominant inheritance.  No locus or mutation has been identified.

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

Unknown.

References
Article Title: 

Hunter Syndrome (MPS II)

Clinical Characteristics
Ocular Features: 

Corneal clouding may be noted as early as 6 months of age but is usually absent. When present it is milder than in some other forms of mucopolysaccharidosis.  A pigmentary retinopathy with variable severity is often present.  The disc may be elevated and appears swollen.  Secondary optic atrophy may be seen in long standing cases.

Systemic Features: 

Mild to severe developmental delays are common and mental retardation has been reported in some cases.  There is often 'pebbling' of the skin over the neck and chest.  Joint stiffness, short stature, and skeletal deformities are common.   Many have short necks, a protuberant abdomen, a broad chest, and facial coarseness.  Hepatosplenomegaly, hearing loss, hernias, and carpal tunnel syndrome are often present.  The skull is large with a J-shaped sella, the vertebral bodies are hypoplastic anteriorly, the pelvis and femoral heads are hypoplastic and the diaphyses are expanded.

A severe form, type A, has its onset in the first two to four years of life, with more rapid progression and death commonly by adolescence.  Many patients have obstructive pulmonary disease and heart failure.  The IDS deficiency is similar to that of type B which is less severe and compatible with life into the 7th decade.  Intelligence is often normal in type B.

Genetics

Hunter syndrome, or MPS II, is one of seven lysosomal enzyme deficiencies responsible for the degradation of mucopolysaccharides, and the only one known to be X-linked (Xq28).  The mutation in IDS leads to a deficiency of iduronate sulfatase resulting in accumulation of dermatan and heparin sulfate.  Rare affected females may have chromosomal deletions instead of a simple mutation in IDS.

Pedigree: 
X-linked recessive, carrier mother
X-linked recessive, father affected
Treatment
Treatment Options: 

Various therapies are under development including enzyme replacement, gene transfers, and bone marrow transplantation.  Human iduronate-2-sulfatase (Idursulfase) has been used with encouraging signs but it is too early to determine the long term effectiveness.

References
Article Title: 

Sorsby Macular Coloboma Syndrome

Clinical Characteristics
Ocular Features: 

Macular colobomas, usually bilateral, are the major ocular feature of this oculoskeletal disorder.  These are non-progressive and are generally heavily pigmented.  Vision is, of course, severely reduced (20/200) and horizontal or pendular nystagmus is a feature in some cases.

Systemic Features: 

The systemic features are primarily skeletal.  Patients have short-limbed dwarfism and brachydactyly of the type B variety.  The thumbs and sometimes the large toes may be broad and bifid.  The distal two phalanges sometimes short, absent, or duplicated and the nails can be dysplastic or absent. Syndactyly of several digits in both hands and feet is common.  The ears are large and protuberant and some patients have deafness.  Oligodontia may be present.  Cartilage can have diastrophic changes.  Mental development is normal.

Genetics

In the few families reported, the transmission pattern is vertical suggesting autosomal dominant inheritance but no mutation or locus has been reported.  The mutation causing brachydactyly type B1 was not present in several cases.

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

Surgical treatment of digital anomalies can be beneficial.  Low vision aids could be helpful as well.

References
Article Title: 

Spondyloepiphyseal Dysplasia Congenita

Clinical Characteristics
Ocular Features: 

Patients characteristically have vitreous abnormalities described as veils or stands.  The central vitreous may undergo liquefaction and the peripheral vitreous sometimes creates traction on the retina.  High myopia with progression is common and a significant proportion of patients suffer detachments of the retina even in the absence of myopia.  Lattice degeneration is frequently seen.  Most patients have 20/50 or better vision.

Systemic Features: 

Dwarfism with kyphosis and a barrel chest are characteristic.  The vertebrae are often flattened and malformed and the neck is short.  Delayed ossification in the epiphyses and the os pubis is common.  The disorder can be evident at birth but the full syndrome may not be evident until 3 or 4 years of age.  Radiologic studies are important in making the diagnosis.

Genetics

This is generally considered an autosomal dominant disorder secondary to mutations in the COL2A1 gene impacting type II collagen.  This type of collagen is found primarily in cartilage and vitreous and a number of type II collagenopathy disorders are associated with vitreoretinopathy and joint disease of which Stickler syndrome type I (609508, 108300) is the most common.  Other disorders in this database caused by mutations in COL2A1 are: Kniest dysplasia (156550), Stickler syndromes type I (609508, 108300 ) and II (604841), vitreoretinopathy with epiphyseal dysplasia (120140), and spondyloepiphyseal dysplasia congenita (183900).

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

Cervical fusion is sometimes used when odontoid hypoplasia leads to hypermobility of the cervical vertebrae.  Retinal detachments, of course, need to be repaired.

References
Article Title: 

Peters-Plus Syndrome

Clinical Characteristics
Ocular Features: 

Peters anomaly (306229) usually occurs as an isolated ocular malformation and is often unilateral.  However, in some patients with bilateral involvement it is part of a systemic syndrome or other congenital conditions such as chromosomal deletions and the fetal alcohol syndrome.  It is called Peters Plus syndrome in the condition described here because of the association of a specific combination of systemic features.

The ocular features are consistent with dysgenesis of the anterior chamber.  The clinical picture is highly variable but generally consists of iris adhesions to the cornea centrally (classical Peters anomaly), occasionally lenticular adhesions as well, and thinning of the central corneal stroma.  As a result, the cornea may become edematous, cataracts may develop, and glaucoma is common.

Systemic Features: 

Peters-plus syndrome consists of Peters anomaly plus various degrees of developmental delays and intellectual deficits, short digits and short stature, and cleft lip and palate.  The facies is said to be characteristic due to a prominent forehead, narrow palpebral fissures, and a cupid's bow-shaped upperlip. There may be preauricular pits present and the neck is often broad.  The ears may be prominent.  Congenital heart defects are present in a third of patients and a few have genitourinary anomalies.

Genetics

This is an autosomal recessive disorder of glycosylation caused by a mutation in the B3GALTL gene on chromosome 13 (13q12.3).  At least some patients have a splicing mutation in this gene leading to a skipping of exon 8.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

Treatment is directed at sight preservation by correcting the major ocular defects such as glaucoma and iridocorneal adhesions.  Corneal transplants and cataract removal are sometimes required.  Releasing the anterior synechiae can lead to significant clearing of the corneal edema.  Growth hormone replacement therapy may be beneficial.

References
Article Title: 

The Peters' plus syndrome: a review

Maillette de Buy Wenniger-Prick LJ, Hennekam RC. The Peters' plus syndrome: a review. Ann Genet. 2002 Apr-Jun;45(2):97-103. Review.

PubMed ID: 
12119218
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