autosomal recessive

Mitochondrial DNA Depletion Syndrome 3

Clinical Characteristics
Ocular Features: 

Nystagmus, disconjugate eye movements, and "optic dysplasia" have been noted.

Systemic Features: 

Infants feed poorly which is frequently associated with vomiting, failure to thrive, and growth delay.  They are hypothermic, hypoglycemic, and often jaundiced with signs of liver failure noted between birth and 6 months of age and death by approximately 1 year of age.  Hepatosplenomegaly is present early with abnormal liver enzymes, cholestasis, steatosis, and hepatocellular loss followed by cirrhosis with portal hypertension.  Metabolic acidosis, hyperbilirubinemia, hypoalbuminemia, and hypoglycemia are often present.  Mitochondrial DNA depletion in the liver approaches 84-90%.

All patients have encephalopathic signs with evidence of cerebral atrophy, microcephaly, hypotonia.  Hyperreflexia may be present and some infants have seizures.  Muscle tissue, however, has normal histology and respiratory chain activity.

Genetics

This disorder results from homozygous or compound heterozygous mutations in the DGUOK gene (2p13).

The same gene is mutated in PEOB4 (617070).

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

There is no effective treatment.  Liver transplantation in one infant was unsuccessful.  

References
Article Title: 

External Ophthalmoplegia, Progressive, with mtDNA Deletions, AR 4

Clinical Characteristics
Ocular Features: 

Patients have adult onset (6th to 7th decade of life) and progressive ptosis and external ophthalmoplegia of variable severity.

Systemic Features: 

There is a great deal of clinical heterogeneity in this condition.  Some patients have adult onset proximal and limb girdle progressive muscle weakness.  Other individuals complain of exercise-induced muscle pain and increased weakness.  Dysphagia and dysphagia may be present.  More widespread signs such as peripheral neuropathy, hearing impairment, cortical atrophy, and liver disease are variably present.  

Genetics

Compound heterozygous mutations in the DGUOK (deoxyguanosine kinase) gene (2p13) have been identified in this disorder.  Multiple deletions in the mitochondrial DNA of skeletal muscle have been found as well.    

Biallelic mutations in the DGUOK gene also cause more widespread disease as evidenced in the mitochondrial DNA depletion syndrome MTDPS3 (251880). 

A similar condition, External Ophthalmoplegia, Progressive, with mtDNA Deletions, AR 3, (617069) is caused by mutations in the TK2 gene.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

Ptosis surgery may be of benefit.

References
Article Title: 

External Ophthalmoplegia, Progressive, with mtDNA Deletions, AR 3

Clinical Characteristics
Ocular Features: 

The ophthalmoplegia is adult in onset (approx. age 40 years) and progressive.  Severe blepharoptosis is an associated sign.

Systemic Features: 

Proximal muscle weakness and atrophy in the shoulder girdle and legs were features in the two reported patients.  Rising from a squatting position and walking up stairs may be particularly difficult.  Dysarthria and dysphagia are associated findings.

Muscle biopsy showed mitochondrial myopathy.  Multiple mtDNA deletions occur in skeletal muscles.  

Genetics

One family with two sisters has been reported with this condition.  Both had compound heterozygous mutations in the thymidine kinase gene (TK2) (16q21) and multiple deletions in mitochondrial DNA.

A similar condition, External Ophthalmoplegia, Progressive, with mtDNA Deletions, AR 4, (617070) is caused by mutations in the DGUOK gene. 

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

There is no treatment for the generalized condition but blepharoplasty may be required.

References
Article Title: 

Night Blindness, Congenital Stationary, CSNB1H

Clinical Characteristics
Ocular Features: 

Night blindness is a feature of many pigmentary and other retinal disorders, most of which are progressive.  However, there is also a group of genetically heterogeneous disorders, with generally stable scotopic defects and without RPE changes, known as congenital stationary night blindness (CSNB).  At least 10 mutant genes are responsible with phenotypes so similar that genotyping is usually necessary to distinguish them.  All are caused by defects in visual signal transduction within rod photoreceptors or in defective photoreceptor-to-bipolar cell signaling with common ERG findings of reduced or absent b-waves and generally normal a-waves.  However, the photopic ERG can be abnormal to some degree as well and visual acuity may be subnormal.  In the pregenomic era, subtleties of ERG responses were frequently used in an attempt to distinguish different forms of CSNB.  Genotyping now enables classification with unprecedented precision.

Night blindness in this condition can be detected in early childhood and may be congenital.   Photophobia, reduced cone sensitivity. and mild dyschromatopsia may develop in midlife.  Peripheral field constriction can be demonstrated.  Visual acuity is near normal and there is no nystagmus or high myopia as reported for some other forms of CSNB.   

Systemic Features: 

There are no systemic abnormalities.

Genetics

This is an autosomal recessive disorder resulting from homozygous or compound heterozygous mutations in the GNB3 gene (12p13.31).

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No effective treatment has been reported but the use of tinted lenses can enhance contrast and improve acuity.

References
Article Title: 

Retinitis Pigmentosa 75

Clinical Characteristics
Ocular Features: 

Symptoms of night blindness and tunnel vision (restricted peripheral fields) are present in the first decade of life.  The fundus appearance is typical for retinitis pigmentosa.  Attenuated retinal vessels with a bone spicule pattern of pigment clumping are present.  Evidence of optic atrophy with waxy pallor of the disc is usually visible.   High myopia (>6 diopters) is frequently present.

Systemic Features: 

No systemic disease has been associated with this disorder.

Genetics

This condition generally follows an autosomal recessive inheritance pattern as the result of homozygous mutations in the AGBL5 gene (2p23).

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment has been reported.

References
Article Title: 

Expanding the clinical, allelic, and locus heterogeneity of retinal dystrophies

Patel N, Aldahmesh MA, Alkuraya H, Anazi S, Alsharif H, Khan AO, Sunker A, Al-Mohsen S, Abboud EB, Nowilaty SR, Alowain M, Al-Zaidan H, Al-Saud B, Alasmari A, Abdel-Salam GM, Abouelhoda M, Abdulwahab FM, Ibrahim N, Naim E, Al-Younes B, E AlMostafa A, AlIssa A, Hashem M, Buzovetsky O, Xiong Y, Monies D, Altassan N, Shaheen R, Al-Hazzaa SA, Alkuraya FS. Expanding the clinical, allelic, and locus heterogeneity of retinal dystrophies. Genet Med. 2016 Jun;18(6):554-62.

PubMed ID: 
26355662

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

Cerebral Palsy, Spastic Quadriplegic, 3

Clinical Characteristics
Ocular Features: 

One family with 4 affected sibs has been reported but without detailed information on ophthalmological findings.  Strabismus reported as exotropia in one individual, and "convergent retraction nystagmus" in another was present.  Supranuclear gaze palsy was described in one individual. 

Systemic Features: 

Borderline microcephaly has been reported.  Evidence for global neurologic disease, primarily spasticity, may be present as early as 3 months of age.  Intellectual disability ranges from borderline to severe.  Progression is somewhat variable but by the second decade there may be sufficient spastic quadriparesis and cognitive impairment that full time assistive care is required.  Dysarthria and dysphagia are also features and gastrostomy feeding tubes may be required to maintain nutrition.  Seizures are uncommon.

The MRI does not show major structural abnormalities and an EEG in one patient revealed only bifrontal spike-waves.

Genetics

This condition is caused by homozygous mutations in the ADD3 gene (10q24).

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment is known.

References
Article Title: 

Mutations in gamma adducin are associated with inherited cerebral palsy

Kruer MC, Jepperson T, Dutta S, Steiner RD, Cottenie E, Sanford L, Merkens M, Russman BS, Blasco PA, Fan G, Pollock J, Green S, Woltjer RL, Mooney C, Kretzschmar D, Paisan-Ruiz C, Houlden H. Mutations in gamma adducin are associated with inherited cerebral palsy. Ann Neurol. 2013 Dec;74(6):805-14.

PubMed ID: 
23836506

Heart and Brain Malformation Syndrome

Clinical Characteristics
Ocular Features: 

Microphthalmia is the cardinal ocular malformation.  Hypertelorism has been described.  Poor vision without further description has also been reported.   

Systemic Features: 

The ears are low-set, malformed, and posteriorly rotated.  The forehead is prominent and there is usually a wide anterior fontanel.  The nasal bridge is wide and frequently depressed while the lower lip is full and may be everted and split.  The palate is highly arched.  Physical growth is slow.  A ventricular septal defect is often present while the valves are hypoplastic and the aortic arch can be interrupted.

Microcephaly is often present and there may a profound delay in psychomotor development with truncal hypotonia and hyperreflexia in the limbs.   Brain imaging shows generalized atrophy with decreased myelination.  Cerebellar vermis hypoplasia has been reported.  Two of 5 patients were reported to have Dandy-Walker malformations, and a thin corpus callosum.  Seizures may occur.

Genetics

Homozygous mutations in the SMG9 gene (19q13.31) are responsible for this condition so far reported in 5 individuals in two unrelated consanguineous Arab families.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment has been reported.

References
Article Title: 

Mutations in SMG9, Encoding an Essential Component of Nonsense-Mediated Decay Machinery, Cause a Multiple Congenital Anomaly Syndrome in Humans and Mice

Shaheen R, Anazi S, Ben-Omran T, Seidahmed MZ, Caddle LB, Palmer K, Ali R, Alshidi T, Hagos S, Goodwin L, Hashem M, Wakil SM, Abouelhoda M, Colak D, Murray SA, Alkuraya FS. Mutations in SMG9, Encoding an Essential Component of Nonsense-Mediated Decay Machinery, Cause a Multiple Congenital Anomaly Syndrome in Humans and Mice. Am J Hum Genet. 2016 Apr 7;98(4):643-52.

PubMed ID: 
27018474

Foveal Hypoplasia 2

Clinical Characteristics
Ocular Features: 

The cardinal feature in this condition is foveal hypoplasia which is characterized by the lack of a foveal depression and continuity of all neurosensory layers across the foveal area as revealed by OCT.  This is accompanied by poor visual acuity, nystagmus, and strabismus.  Hypopigmentation of the immediate area has also been reported in some patients.  Visual acuity in one study of 9 patients ranged from 20/50 to 20/200.  The ERG and flash VEP can be normal.  Color vision has been described as normal in some individuals.

Dysgenesis of the anterior segment seems to be family-specific and consists of Axenfeld anomaly or embryotoxon.

Systemic Features: 

In most cases the only features are foveal hypoplasia with or without anterior chamber anomalies.  Three affected sisters in one family were reported to have mild developmental delay.

Genetics

Homozygous mutations in SLC38A8 (16q23.3) are responsible for this disorder. 

For a somewhat similar condition of foveal hypoplasia see FVH1 (136520), which is, however, caused by a different mutation and inherited in an autosomal dominant pattern.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

There is no known treatment.

References
Article Title: 

Leukodystrophy, Hypomyelinating, 13

Clinical Characteristics
Ocular Features: 

Several individuals in one family have been observed with optic atrophy, nystagmus and visual impairment.

Systemic Features: 

Head circumference is normal at birth but later in childhood falls behind in growth.  Neurodevelopment seems to plateau without regression.  Feeding difficulties may be present from birth and may require gastroscopy tube placement.  Motor skills are delayed and expressive language may never develop.  General irritability and increased muscle tone with hyperreflexia are usually present eventually resulting in joint contractures. 

EEGs , electromyography, and nerve conduction studies have been normal in 3 patients.  A brain MRI in one patient showed a leukodystrophic pattern in periventricular areas.  Variable cardiac malfunctions such as heart failure, LVH, and pericarditis were observed in several patients.

Sudden death following a short febrile illness has been reported to occur in three of the six affected children before the age of 15 years. 

Genetics

Homozygous mutations in the C11ORF73 gene (11q14.2) are responsible for this disorder.  Three unrelated families of Ashkenazi Jewish descent have been reported.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No effective treatment has been reported.

References
Article Title: 

Pages

Subscribe to RSS - autosomal recessive