autosomal recessive

Cataracts, Congenital, Autosomal Recessive 2

Clinical Characteristics
Ocular Features: 

Bilateral nuclear lens opacities are either present at birth or noted during infancy.  The cataracts were sufficiently dense that surgery is necessary within several months of age in most patients.  No other ocular disease is present.

Systemic Features: 

No systemic abnormalities are present.

Genetics

CATC2 is an autosomal recessive condition that has been reported in 12 consanguineous Pakistani families.  Homozygous mutations in FYCO1 (3p21.31) segregated with the lens opacities as expected.  Mutations in FYC01 are among the most common causes of congenital cataracts in Pakistan and may account for about 10% of the total genetic load of cataracts in this country.  Mutations in the same gene have been found segregating in several consanguineous Arab families with congenital cataracts as well.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

Cataract surgery is frequently necessary during infancy.

References
Article Title: 

Meckel Syndrome

Clinical Characteristics
Ocular Features: 

The ocular phenotype is highly variable.  The globe is often malformed or may be clinically absent.  Cryptophthalmos, clinical anophthalmia, and microphthalmos with sclerocornea and microcornea have been reported.  Posterior staphylomas, retinal dysplasia, partial aniridia, cataracts, and hypoplasia or absence of the optic nerve are sometimes seen.  Some patients have incompletely formed eyes with shallow anterior chambers, angle anomalies, and a persistent tunica vasculosa with lens opacification.  Histopathology may reveal thinning of the nerve fiber layer and a paucity of retinal ganglion cells.  The retina has been described as dysplastic with foci of rosette-like structures and abundant glial cells.

Systemic Features: 

Meckel or Meckel-Gruber syndrome is a clinically and genetically heterogeneous group of disorders with severe multisystem manifestations.  The triad of cystic renal disease, polydactyly (and sometimes syndactyly), and a skull malformation (usually an encephalocele) is considered characteristic of MKS.  However, these signs are variable and only about 60% of patients have all three features.  Many patients have additional signs such as malformations of the biliary tree, cleft palate (and/or lip), sloping forehead, low-set ears, short neck, low-set ears, ambiguous genitalia, and short, bowed limb bones.  Pulmonary hypoplasia is common which, together with kidney and liver disease, is responsible for the poor prognosis of most infants. 

Many clinical abnormalities resemble those present in the Smith-Lemli-Opitz syndrome (270400) and in Joubert syndrome (213300).

Genetics

Most conditions in this group are inherited in an autosomal recessive pattern.  Mutations in 9 genes have been identified as responsible for some variant of MKS in which there is a considerable range of clinical expression.  There is significant clinical overlap with Joubert syndrome and it is not surprising that at least 5 of these mutations have been identified in both conditions.  Further nosological confusion is generated by those who consider patients with the severe, lethal phenotype to have Meckel syndrome while those with milder disease are labeled Joubert syndrome, regardless of genotype.

Rare heterozygotes have been reported with isolated features such as polydactyly.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

There is no treatment for this syndrome.  The prognosis for life beyond infancy is poor due to the advanced dysfunction of numerous organs such as the kidney, lungs, liver and the central nervous system.

References
Article Title: 

Clinical and genetic heterogeneity in Meckel syndrome

Paavola P, Salonen R, Baumer A, Schinzel A, Boyd PA, Gould S, Meusburger H, Tenconi R, Barnicoat A, Winter R, Peltonen L. Clinical and genetic heterogeneity in Meckel syndrome. Hum Genet. 1997 Nov;101(1):88-92.

PubMed ID: 
9385376

Majewski Syndrome

Clinical Characteristics
Ocular Features: 

No clinical information is available on the ocular features in this disorder.  The fundi have been described as normal in one patient but postmortem histopathology at 8 weeks revealed optic nerve edema with segmental axonal dropout and loss of myelin.  The nerve fiber layer of the retina was prominent with some proliferation of glial tissue.  Early nuclear sclerosis was also present.

Systemic Features: 

This disorder results from a dysgenesis of the cilia and is one of a group of short rib-polydactyly disorders.  Congenital anomalies are found in multiple organs including heart, lungs, skeleton, intestines, genitalia, pancreas, liver, and kidneys.  The diagnostic characteristic of SRPS type II is extreme shortening of the tibia in addition to short ribs in this type of short-limbed dwarfism.

Midline facial clefting, especially cleft lip, is common.  The epiglottis and lungs are often hypoplastic and the kidneys are polycystic.  Polydactyly and polysyndactyly of both pre- and postaxial types are usually present.  Most neonates with SRPS type II do not live beyond infancy.

Genetics

This is an autosomal recessive condition resulting from homozygous mutations in the NEK1 gene (4q33), or, rarely, from digenic biallelic mutations in NEK1 and DYNC2H1 (11q22.3).

Another condition with some of the same features leading to respiratory distress is asphyxiating thoracic dysplasia 1 (208500), or Jeune syndrome.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No effective treatment is available for this condition but surgical treatment could be considered for specific anomalies.

References
Article Title: 

NEK1 mutations cause short-rib polydactyly syndrome type majewski

Thiel C, Kessler K, Giessl A, Dimmler A, Shalev SA, von der Haar S, Zenker M, Zahnleiter D, Stoss H, Beinder E, Abou Jamra R, Ekici AB, Schroder-Kress N, Aigner T, Kirchner T, Reis A, Brandst?SStter JH, Rauch A. NEK1 mutations cause short-rib polydactyly syndrome type majewski. Am J Hum Genet. 2011 Jan 7;88(1):106-14.

PubMed ID: 
21211617

Joubert Syndrome and Related Disorders

Clinical Characteristics
Ocular Features: 

Ocular findings like systemic features are highly variable both within and between families.  Vision can be normal but in other patients it is severely reduced to the range of 20/200.  The pupils may respond sluggishly or even paradoxically to light.  ERG recordings have been reported to be normal in some patients, but absent or reduced in others.  The fundus appearance is often normal but in other individuals the pigmentation is mottled, the retinal arterioles are attenuated, and the macula has a cellophane maculopathy.  Drusen and colobomas are sometimes seen in the optic nerve while occasional patients have typical chorioretinal colobomas.  The eyebrows are often highly arched.

The oculomotor system is frequently involved.  Apraxia to some degree is common with most patients having difficulty with smooth pursuit and saccadic movements.  Compensatory head thrusting is often observed.  A pendular nystagmus may be present while esophoria or esotropia is present in many patients.

Systemic Features: 

There is a great deal of clinical heterogeneity in this group of ciliary dyskinesias.  Developmental delays, cognitive impairment, truncal ataxia, breathing irregularities, and behavioral disorders are among the more common features.  Hyperactivity and aggressiveness combined with dependency require constant vigilance and care.  Postaxial polydactyly is a feature of some cases.  Hypotonia is evident at birth.  Liver failure and renal disease develop in many individuals.  Neuroimaging of the midbrain-hindbrain area reveals agenesis or some degree of dysgenesis of the vermis with the ‘molar tooth sign’ in the isthmus region considered to be a diagnostic sign.  The fourth ventricle is usually enlarged while the cerebellar hemispheres may be hypoplastic.

The facies features are said to be distinctive in older individuals.  The face appears long with frontal prominence due to bitemporal narrowing, the nasal bridge and tip are prominent, the jaw is prominent, the lower lip protrudes, and the corners of the mouth are turned down.

Genetics

This is a clinically and genetically heterogeneous group of disorders with many overlapping features.  Most disorders in this disease category, known as JSRD, are inherited in an autosomal recessive pattern.  Mutations in at least 18 genes have been identified.  One, OFD1 (300804), is located on the X chromosome (Xp22.2).

There are significant clinical similarities with Meckel syndrome (249000) and with Smith-Lemli-Opitz syndrome (270400).

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

Treatment is mostly for specific symptoms such as respiratory distress, renal disease, speech and physical therapy, low vision, and hepatic failure.

References
Article Title: 

Ophthalmological findings in Joubert syndrome

Sturm V, Leiba H, Menke MN, Valente EM, Poretti A, Landau K, Boltshauser E. Ophthalmological findings in Joubert syndrome. Eye (Lond). 2010 Feb;24(2):222-5.

PubMed ID: 
19461662

Retinitis Pigmentosa 1

Clinical Characteristics
Ocular Features: 

Night blindness, the predominant presenting symptom, is often noted in the first decade of life but may not be a significant complaint until the third decade.  Concentric peripheral field loss likewise follows a similar timeline.  ERG responses progressively decrease in amplitude and may become undetectable in the second decade.  The retinal disease progresses relentlessly, albeit slowly, as the result of photoreceptor degeneration and most patients have severe visual handicaps by midlife but there is considerable clinical variation.  The pigmentary retinopathy is typical for classical retinitis pigmentosa with vascular attenuation, perivascular bone-spicule pigment clumping, optic atrophy, and generalized retinal atrophy with relative sparing of the macula early in the disease.  Lens opacities in late stages of the disease are common.

Systemic Features: 

No systemic disease is associated with the ocular disorder caused by mutations in RP1.

Genetics

Multiple heterozygous, homozygous, and compound heterozygous mutations in the RP1 gene (8q12.1) sometimes called the oxygen-regulated photoreceptor protein 1 or ORP1 gene are responsible for this disorder.  The protein product is active specifically in retinal photoreceptors.  Retinitis pigmentosa 1 is generally considered to be an autosomal dominant disorder and accounts for 5-7% of dominantly inherited RP disease.  However, recent reports suggest that some mutations in RP1 are responsible for familial cases transmitted in an autosomal recessive pattern in which the clinical disease is more severe. 

More than 20 different mutant genes have been associated with autosomal dominant RP but many cases lack a family history suggesting additional genetic heterogeneity remains.  Reduced penetrance and variable expressivity characteristic of genetic disease likely contributes to the clinical heterogeneity as well.  For more about autosomal dominant retinitis pigmentosa, see Retinitis Pigmentosa, AD (180380, 268000).  

Pedigree: 
Autosomal dominant
Autosomal recessive
Treatment
Treatment Options: 

Photoreceptor transplantation has been tried in a number of patients without improvement in central vision or interruption in the rate of vision loss.  Longer term results are needed.  Resensitizing photoreceptors with halorhodopsin using archaebacterial vectors shows promise in mice.  High doses of vitamin A palmitate slow the rate of vision loss but plasma levels and liver function need to be checked at least annually.  Oral acetazolamide can be helpful in reducing macular edema.

Low vision aids and mobility training can be facilitating for many patients.  Cataract surgery may restore several lines of vision at least temporarily.

Several pharmaceuticals should be avoided, including isotretinoin, sildenafil, and vitamin E.

References
Article Title: 

External Ophthalmoplegia with Progressive Scoliosis

Clinical Characteristics
Ocular Features: 

Horizontal ophthalmoplegia is the ocular hallmark of this condition.  It is often present at birth with complete lack of horizontal gaze but in other individuals develops sometime in the first decade of life.  Horizontal smooth pursuit, saccades, optokinetic nystagmus, and vestibuloocular responses are lacking.  Vertical pursuit movements are usually intact except for smooth pursuit which is often saccadic.  Pendular nystagmus (usually horizontal) may be present and head shaking accompanies the nystagmus in some patients.  Many patients are orthophoric but some have a mild esotropia and/or vertical deviation.  The degree of convergence is variable.  Amblyopia does not usually occur and vision has been described as normal or near normal in spite of the presence of nystagmus.  Fusion and some degree of stereoacuity are generally present.  Compensatory head motion can effectively mask the horizontal palsy.

Some individuals are considered to have Duane retraction syndrome or congenital esotropia before the scoliosis becomes apparent.

Systemic Features: 

Progressive thoracolumbar scoliosis begins early in the first decade of life and may be evident by 2 years of life.  MRI reveals hypoplasia of the pons and cerebellar peduncles and electrophysiology studies provides evidence of abnormal (uncrossed) corticospinal and dorsal column-medial lemniscus pathways.  Cranial nerves VI and III seem to be intact.

Genetics

Homozygous mutations in the ROBO3 gene (11q24.2) are responsible for this autosomal recessive disorder.  The ROBO3 protein product is important for normal midline axon crossing in the brainstem. Consanguinity is common among parents.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

Scoliosis may require surgical stabilization.  Physical therapy can be beneficial.

References
Article Title: 

Mutations in a human ROBO gene disrupt hindbrain axon pathway crossing and morphogenesis

Jen JC, Chan WM, Bosley TM, Wan J, Carr JR, R?ob U, Shattuck D, Salamon G, Kudo LC, Ou J, Lin DD, Salih MA, Kansu T, Al Dhalaan H, Al Zayed Z, MacDonald DB, Stigsby B, Plaitakis A, Dretakis EK, Gottlob I, Pieh C, Traboulsi EI, Wang Q, Wang L, Andrews C, Yamada K, Demer JL, Karim S, Alger JR, Geschwind DH, Deller T, Sicotte NL, Nelson SF, Baloh RW, Engle EC. Mutations in a human ROBO gene disrupt hindbrain axon pathway crossing and morphogenesis. Science. 2004 Jun 4;304(5676):1509-13.

PubMed ID: 
15105459

Dyskeratosis Congenita

Clinical Characteristics
Ocular Features: 

The conjunctiva and eyelids are prominently involved as part of the generalized mucocutaneous disease.  Keratinization of the lid margins, absent lacrimal puncta, trichiasis, cicatrizing conjunctivitis, entropion, ectropion, blepharitis, sparse eyelashes, and symblephara are important features.  The cornea is also involved with keratinization of the epithelial surface and vascularization.  The nasolacrimal duct is sometimes blocked.

Systemic Features: 

Dyskeratosis congenita consists of a heterogeneous (genetic and clinical) group of inherited bone marrow failure and premature aging syndromes with the common feature of shortened telomeres.  There is considerable variability in the clinical features.  Prominent manifestations include nail dysplasia, oral leukoplakia, abnormal dentition, and reticulated skin pigmentation. Some patients have cognitive impairments.  Liver failure, testicular atrophy, pulmonary fibrosis, aplastic anemia, and osteoporosis along with features of aging such as premature grey hair and loss are typical.  There is an increased risk of malignancies, especially acute myelogenous leukemia.  Bone marrow failure is the major cause of early death.

Genetics

At least three autosomal dominant, three autosomal recessive, and one X-linked form of dyskeratosis congenita are recognized.  Mutations in at least 7 genes have been implicated.

Autosomal dominant disease can result from mutations in the TERC gene (DKCA1; 3q36.2; 127550), the TERT gene (DKCA2; 5p15.33; 613989), and the TINF2 gene (DKCA3; 14q12; 613990).  Mutations in the TINF2 gene are also responsible for R?(c)v?(c)sz syndrome (268130) with many features of DKC in addition to ocular findings of an exudative retinopathy resembling Coats disease.

Autosomal recessive disease is caused by mutations in the NOP10 (NOLA3) gene (DCKB1; 224230; 15q14-q15), the  NHP2 (NOLA2) gene (DKCB2; 5q35; 613987), and the WRAP53 gene (DKCB3; 17p13; 613988).  Mutations in the TERT gene may also cause autosomal recessive disease known as DKCB4 (613989).  

The X-linked disease (DKCX) (Zinsser-Engman-Cole syndrome) results from a mutation in the DKC1 gene (Xq28; 305000).  The same gene is mutated in Hoyeraal-Hreidarsson syndrome (300240) which some consider to be a more severe variant of dyskeratosis congenita with the added features of immunodeficiency, microcephaly, growth and mental retardation, and cerebellar hypoplasia.  At least one patient had an exudative retinopathy.

The majority of mutations occur in genes that provide instructions for making proteins involved in maintainence of telemeres located at the ends of chromosomes.  Shortened telomeres can result from maintainence deficiencies although the molecular mechanism(s) remain elusive.

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

Treatment for DKC with hematopoietic stem cell transplantation can be curative but its long-term efficacy is poor.  Some advocate androgen therapy first.  Lifelong cancer surveillance and frequent ocular and dental evaluations are important with specific treatment as indicated.

References
Article Title: 

Ataxia with Oculomotor Apraxia 2

Clinical Characteristics
Ocular Features: 

Patients with this disorder have difficulty initiating voluntary ocular movements upon command or following targets (oculomotor apraxia).  This feature is not as prominent or frequent in AOA2 (56%) as it is in ataxia with oculomotor apraxia 1 (208920).  Gaze changes are often initiated first by head thrusting, followed by saccadic eye movements. One may test for this by holding the head whereupon the patient is unable to move the eyes.  Strabismus and nystagmus are present in a significant proportion of patients.  Optokinetic nystagmus is impaired.

Systemic Features: 

Initial development proceeds normally but cerebellar ataxia with significant gait problems appear toward the end of the first decade of life and sometimes not until the third decade (mean age of onset 15 years).   Distal muscle weakness and atrophy are often seen.  Mental decline has been observed in a few individuals but does not occur until midlife.  Sensorimotor deficits are present in many patients.  Tremors, dystonia, and choreiform movements are sometimes seen.  Many patients become wheelchair-bound by the 4th decade of life.

Cerebellar atrophy is revealed by MRI.  Serum alpha-fetoprotein concentrations are usually elevated while serum creatine kinase is increased in some patients.  Circulating cholesterol may also be above normal.  Mild serum changes in these components may be seen in heterozygotes.  Hypoalbuminemia is not present in AOA2.

Genetics

Homozygous mutations in SETX (9q34.13) are responsible for this disorder. 

Ataxia with oculomotor apraxia 2 is distinguished from ataxia-telangiectasia (208900) by the lack of telangiectases and immunological deficiencies. It differs from ataxia with oculomotor apraxia 1 (208920) in having a somewhat later onset, somewhat slower course, and milder oculopraxic manifestations. Cogan-type oculomotor apraxia (257550) lacks other neurologic signs. Oculomotor apraxia may be the presenting sign in Gaucher disease (230800, 230900, 231000).

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

There is no beneficial treatment for the neurological disease but physical therapy, speech therapy, and sometimes special education can be helpful.

References
Article Title: 

Epidemiological, clinical, paraclinical and molecular study of a cohort of 102 patients affected with autosomal recessive progressive cerebellar ataxia from Alsace, Eastern France: implications for clinical management

Anheim M, Fleury M, Monga B, Laugel V, Chaigne D, Rodier G, Ginglinger E, Boulay C, Courtois S, Drouot N, Fritsch M, Delaunoy JP, Stoppa-Lyonnet D, Tranchant C, Koenig M. Epidemiological, clinical, paraclinical and molecular study of a cohort of 102 patients affected with autosomal recessive progressive cerebellar ataxia from Alsace, Eastern France: implications for clinical management. Neurogenetics. 2010 Feb;11(1):1-12.

PubMed ID: 
19440741

Ataxia with oculomotor apraxia type 2: a clinical, pathologic, and genetic study

Criscuolo C, Chessa L, Di Giandomenico S, Mancini P, Sacc?+ F, Grieco GS, Piane M, Barbieri F, De Michele G, Banfi S, Pierelli F, Rizzuto N, Santorelli FM, Gallosti L, Filla A, Casali C. Ataxia with oculomotor apraxia type 2: a clinical, pathologic, and genetic study. Neurology. 2006 Apr 25;66(8):1207-10.

PubMed ID: 
16636238

Cataracts, Congenital, Autosomal Recessive 4

Clinical Characteristics
Ocular Features: 

This type of cataract has been reported in a single consanguineous family in which 4 sibs (2 males and 2 females) were diagnosed with cataracts shortly after birth.  Open angle glaucoma developed in two individuals at the age of 7 and 8 years.  The lens opacification involves primarily the posterior subcapsular area.  No genital abnormalities were found in this family.

Another unrelated individual developed progressive cataracts from the age of 2 years.  At cataract surgery it was noted that the posterior capsules were abnormal with thinning of one and a frank lenticonus in the other.

Systemic Features: 

Hypospadias was present in an unrelated male with an inversion of chromosome 9 involving at least two genes.

Genetics

This is an autosomal recessive disorder resulting from homozygous mutations in the TDRD7 gene (9p22.33).  Normal function of the gene in vertebrates is required for posttranscriptional control of mRNAs critical to normal lens development.

The single unrelated individual with cataracts and hypospadias had an inversion (inv(9)(q22.33q34.11). One of the two breakpoints (9q34.11) involved the gene NR5A1 which is essential for sexual differentiation.  The ocular and genital phenotypes therefore are likely independent. 

The Tdrd7 gene is expressed in lens fibers and its malfunction causes cataracts in mice.  The evolution of lens opacification in mice closely resembles that observed in the reported patient with cataracts and hypospadias.  Some mutant mice develop open angle glaucoma complete with optic atrophy and nerve cupping.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

Cataract surgery may be indicated and patients should be monitored and treated for glaucoma.

References
Article Title: 

Mutations in the RNA granule component TDRD7 cause cataract and glaucoma

Lachke SA, Alkuraya FS, Kneeland SC, Ohn T, Aboukhalil A, Howell GR, Saadi I, Cavallesco R, Yue Y, Tsai AC, Nair KS, Cosma MI, Smith RS, Hodges E, Alfadhli SM, Al-Hajeri A, Shamseldin HE, Behbehani A, Hannon GJ, Bulyk ML, Drack AV, Anderson PJ, John SW, Maas RL. Mutations in the RNA granule component TDRD7 cause cataract and glaucoma. Science. 2011 Mar 25;331(6024):1571-6.

PubMed ID: 
21436445

Sengers Syndrome

Clinical Characteristics
Ocular Features: 

This is a mitochondrial DNA depletion syndrome in which congenital cataracts are the hallmark ocular feature.  The bilateral lens opacification is usually total at birth or within the first few weeks of life as manifested by leucocoria. Lens extraction is necessary within the first 6 months of life but visual rehabilitation is nearly always compromised postoperatively by nystagmus and strabismus.  In one series only one eye recovered to 20/40 but the average postoperative acuity was in the range of 20/200 and virtually all students require special education in schools for the visually impaired.  Axial myopia is common with most patients having myopic fundus changes and requiring less than +10 diopters of aphakic correction.  Pale optic disks and a pigmentary retinopathy were noted among 8 of 18 eyes in one series.  Mild and inconsistent dyschromatopsia has been reported in a few patients.  The ERG sometimes shows diminished rod and cone function.

Systemic Features: 

Hypertrophic cardiomyopathy is often diagnosed within a fews days after birth but 40% may escape detection until the second or third decade of life.  It is usually progressive and often fatal in the neonatal period.  Myopathy involves both cardiac and skeletal muscles.  Generalized hypotonia, exercise intolerance, and delayed motor development are important features in the majority of patients.  Metabolic lactic acidosis occurs with relatively minimal excercise.  Skeletal muscle biopsies show ragged-red fibers with combined deficiencies of mitochondrial complexes I, III, and IV along with severe depletion of mtDNA.  Increased urine levels of 3-methylglutaconic have been reported.

The central nervous system is usually not involved and mental development is normal if lactic acidosis is controlled.  However, several children with mental retardation have been reported.

Genetics

Homozygous or compound heterozygous mutations in AGK (7p34), a lipid metabolism gene, are responsible for this condition.  There is considerable variation in the severeity of the phenotypic features but no ocular or cardiac disease has been found in heterozygotes. 

The same gene was found to be mutated in an autosomal recessive congenital cataract (614691) in a single reported sibship. Thorough systemic evaluation found no evidence of cardiac and skeletal muscle disease.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

Surgical removal of cataracts may be indicated.

References
Article Title: 

Lack of the mitochondrial protein acylglycerol kinase causes Sengers syndrome

Mayr JA, Haack TB, Graf E, Zimmermann FA, Wieland T, Haberberger B, Superti-Furga A, Kirschner J, Steinmann B, Baumgartner MR, Moroni I, Lamantea E, Zeviani M, Rodenburg RJ, Smeitink J, Strom TM, Meitinger T, Sperl W, Prokisch H. Lack of the mitochondrial protein acylglycerol kinase causes Sengers syndrome. Am J Hum Genet. 2012 Feb 10;90(2):314-20.

PubMed ID: 
22284826

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