cardiac valve dysfunction

Arthrogryposis, Perthes Disease, and Upward Gaze Palsy

Clinical Characteristics
Ocular Features: 

Upward gaze is restricted and attempts to do so are associated with exotropia.

Systemic Features: 

Arthrogryposis with restricted joint mobility is present in both proximal and distal joints, including hips, elbows, hands, and knees.  It is usually evident early in infancy when parents note "tight joints".  Other joint deformities present to some degree are "trigger finger" deformities found in the middle fingers and thumbs.  Hip pain and difficulty walking as early as 3 years of age can be signs of avascular necrosis of the femoral head (Perthes disease).   

Pyloric stenosis can lead to severe, recurrent vomiting.  Pulmonic stenosis is commonly present and there are often cardiac septal defects as well as valvular malfunctions.  Bronchial asthma is a feature.

Genetics

One extended consanguineous Saudi family with three affected females has been reported.  No similar findings are present in the parents and the condition is most likely transmitted as an autosomal recessive.  A homozygous mutation in NEK9 (14q24) has been associated with this condition.

Heterozygous mutations in the same gene have been identified in 3 patients with nevus comedonicus (617025).  

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

Flexion deformities may be at least partially alleviated by surgery and is especially beneficial for digital function.  Pyloric stenosis and cardiac valve disease may respond to surgery.

References
Article Title: 

Mutations in NEK9 Cause Nevus Comedonicus

Levinsohn JL, Sugarman JL; Yale Center for Mendelian Genomics, McNiff JM, Antaya RJ, Choate KA. Somatic Mutations in NEK9 Cause Nevus Comedonicus. Am J Hum Genet. 2016 May 5;98(5):1030-7.

PubMed ID: 
27153399

Accelerating matchmaking of novel dysmorphology syndromes through clinical and genomic characterization of a large cohort

Shaheen R, Patel N, Shamseldin H, Alzahrani F, Al-Yamany R, ALMoisheer A, Ewida N, Anazi S, Alnemer M, Elsheikh M, Alfaleh K, Alshammari M, Alhashem A, Alangari AA, Salih MA, Kircher M, Daza RM, Ibrahim N, Wakil SM, Alaqeel A, Altowaijri I, Shendure J, Al-Habib A, Faqieh E, Alkuraya FS. Accelerating matchmaking of novel dysmorphology syndromes through clinical and genomic characterization of a large cohort. Genet Med. 2016 Jul;18(7):686-95.

PubMed ID: 
26633546

Maroteaux-Lamy Syndrome (MPS VI)

Clinical Characteristics
Ocular Features: 

Corneal clouding is the cardinal ocular feature and is often visible by 5 years of age.  Several adult patients have had glaucoma with both open and closed angles.  The mechanism is unknown.  Optic nerve compression or secondary edema can cause a relatively sudden loss of vision.

Systemic Features: 

The lysosomal accumulation of glycosaminoglycans is responsible for the widespread signs and symptoms found in this disease.  Bone destruction in shoulders, hips and skull is often seen by the second decade of life and may become evident later in the knees and spine.  Early growth may be normal but eventually slows resulting in short stature.  Dysplasia of bones comprising these joints leads to stiffness and restricted movement.  The face is dysmorphic with coarse features.  Bone dysplasia and facial dysmorphism may be seen at birth.  Myelopathy and even tetraplegia can result from vertebral compression.  Intelligence is often normal although more severely affected individuals may have some cognitive defects.  Hepatosplenomegaly is common and compromised respiratory function can result in reduced physical stamina.  The tongue is usually enlarged.  Accumulation of dermatan sulfate in heart valves may produce insufficiency or restriction of outflow.

Genetics

MPS VI is a lysosomal storage disease inherited in an autosomal recessive pattern.  The responsible mutations lie in ARSB (5q11-q13), the gene that encodes the enzyme arylsulfatase B.  The phenotype results from defective dermatan sulfate breakdown with lysosomal accumulation.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

Enzyme replacement therapy with galsulfase (Naglazyme®) is beneficial in alleviating some of the manifestations of this disease.  Orthopedic surgery for specific deformities may be necessary.  Visually significant corneal opacification may require corneal transplantation.

References
Article Title: 

Threshold effect of urinary glycosaminoglycans and the walk test as indicators of disease progression in a survey of subjects with Mucopolysaccharidosis VI (Maroteaux-Lamy syndrome)

Swiedler SJ, Beck M, Bajbouj M, Giugliani R, Schwartz I, Harmatz P, Wraith JE, Roberts J, Ketteridge D, Hopwood JJ, Guffon N, S?deg Miranda MC, Teles EL, Berger KI, Piscia-Nichols C. Threshold effect of urinary glycosaminoglycans and the walk test as indicators of disease progression in a survey of subjects with Mucopolysaccharidosis VI (Maroteaux-Lamy syndrome). Am J Med Genet A. 2005 Apr 15;134A(2):144-50.

PubMed ID: 
15690405

Noonan Syndrome

Clinical Characteristics
Ocular Features: 

Noonan syndrome has prominent anomalies of the periocular structures including downward-slanting lid fissures, hypertelorism, epicanthal folds, high upper eyelid crease, and some limitation of ocular mobility most commonly of the levator.  Ptosis and strabismus are present in nearly half of patients. Amblyopia has been found in one-third of patients and almost 10% have nystagmus.  Corneal nerves are prominent and a substantial number of individuals have optic nerve abnormalities including drusen, hypoplasia, colobomas and myelinated nerves.  Evidence of an anterior stromal dystrophy, cataracts, or panuveitis is seen in a minority of patients.  About 95% of patients have some ocular abnormalities.

Systemic Features: 

Patients are short in stature.  Birth weight and length may be normal but lymphedema is often present in newborns.  The neck is usually webbed (pterygium colli) and the ears low-set.  The sternum may be deformed.  Cardiac anomalies such as coarctation of the aorta, pulmonary valve stenosis, hypertrophic cardiomyopathy, and septal defects are present in more than half of patients.  Dysplasia of the pulmonic valve has been reported as well.  Thrombocytopenia and abnormal platelet function with abnormalities of coagulation factors are found in about 50% of cases resulting in easy bruising and prolonged bleeding.  Cryptorchidism is common in males.  Some patients have intellectual disabilities with speech and language problems.  Most have normal intelligence.   

Parents of affected children often have subtle signs of Noonan Syndrome.

Genetics

This is an autosomal dominant disorder that can result from mutations in at least 7 genes.  Nearly half are caused by mutations in the PTPN11 gene (12q24.1) (163950).  Mutations in the SOS1 gene (2p22-p21) cause NS4 (610733) and account for 10-20% of cases, those in the RAF1 gene (3p25) causing NS5 (611553) for about the same proportion, and mutations in the KRAS gene (12p12.1) (NS3; 609942) cause about 1%.  Mutations in BRAF (7q34) causing NS7 (613706), NRAS (1p13.2) responsible for NS6 (613224), and MEK1 genes have also been implicated and it is likely that more mutations will be found.  The phenotype is similar in all individuals but with some variation in the frequency and severity of specific features.  New mutations are common. 

Several families suggestive of autosomal recessive inheritance (NS2) (605275) have been reported but no homozygous genotype has been identified.

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

There is no treatment for most of the developmental problems but some patients benefit from special education. Cardiac surgery may be required in some cases to correct the developmental defects.  Bleeding problems can be treated with supplementation of the defective coagulation factor.  Growth hormone therapy can increase the growth velocity.

References
Article Title: 

Update on turner and noonan syndromes

Chacko E, Graber E, Regelmann MO, Wallach E, Costin G, Rapaport R. Update on turner and noonan syndromes. Endocrinol Metab Clin North Am. 2012 Dec;41(4):713-34. Epub 2012 Sep 28.

PubMed ID: 
23099266
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