mental retardation

Cataracts, Congenital, Intellectual Disability, Abnormal Striatum, and ADHD

Clinical Characteristics
Ocular Features: 

Cataracts (not further described) were described as congenital although the diagnosis was usually made early in the first decade of life.  One patient was diagnosed at the age of 8 years with glaucoma and a cloudy cornea of the left eye.  Another patient had cataract surgery.  Visual acuities have not been reported.

Systemic Features: 

Four members of a consanguineous Saudi family have been reported with growth and mental retardation, microcephaly, dystonia, and spasticity.  IQs in the range of 77-89 were reported.  Linguistic delay is common.  Dysarthria and decreased cognitive function are present.  MRIs revealed thinning of the lentiform nucleus and swelling of the caudate heads.  

Genetics

Homozygous mutations in the KCNA4 (11p14.1) (176266) gene are responsible for this disorder.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment is available for the general condition.  Cataract surgery may be considered.

References
Article Title: 

KCNA4 deficiency leads to a syndrome of abnormal striatum, congenital cataract and intellectual disability

Kaya N, Alsagob M, D'Adamo MC, Al-Bakheet A, Hasan S, Muccioli M, Almutairi FB, Almass R, Aldosary M, Monies D, Mustafa OM, Alyounes B, Kenana R, Al-Zahrani J, Naim E, Binhumaid FS, Qari A, Almutairi F, Meyer B, Plageman TF, Pessia M, Colak D, Al-Owain M. KCNA4 deficiency leads to a syndrome of abnormal striatum, congenital cataract and intellectual disability. J Med Genet. 2016 Aug 31. pii: jmedgenet-2015-103637. doi: 10.1136/jmedgenet-2015-103637. [Epub ahead of print].

PubMed ID: 
27582084

Mental Retardation, X-Linked 99, Syndromic, Female-Restricted

Clinical Characteristics
Ocular Features: 

Palpebral fissures are generally shortened and may slant up or down.  Cataracts of unknown morphology have been reported and strabismus is common.

Systemic Features: 

The systemic phenotype is highly variable.  Skull and facial anomalies are common with brachycephaly, bitemporal narrowing, and a broad low nasal bridge. There is general developmental delay in both motor and cognitive abilities.  Patients are short in stature while scoliosis, hip dysplasia, and post-axial polydactyly may be present.  The teeth may be malformed and numerous (29%) of individuals have hypertrichosis.  Nearly a third of individuals have a cleft palate/bifid uvula.   Heart malformations, primarily atrial septal defects, are found in about half of affected individuals and urogenital anomalies such as renal dysplasia are relatively common.  Feeding difficulties have been reported while anal atresia is present in about half of patients.   

Brain imaging reveals hypoplasia of the corpus callosum, enlarged ventricles, Dandy-Walker malformations, cerebellar hypoplasia, and abnormal gyration patterns in the frontal lobe.  Generalized hypotonia has been diagnosed in half of reported patients and seizures occur in 24%.

Genetics

This female-restricted syndrome is caused by heterozygous mutations in the USP9X gene (Xp11.4).  X-chromosome inactivation is skewed greater than 90% in the majority of females but the degree of skewing in one study was independent of clinical severity.  The majority of cases occur de novo.

In males, hemizygous mutations in the USP9X gene (300919) cause a somewhat similar disorder (MRX99) without the majority of the congenital malformations having mainly the intellectual disabilities, hypotonia, and behavioral problems.

Pedigree: 
X-linked dominant, mother affected
Treatment
Treatment Options: 

There is no known treatment for the general disorder but individual anomalies or defects such as atrial septal defects, cleft palate, and anal atresia might be surgically corrected.

References
Article Title: 

De Novo Loss-of-Function Mutations in USP9X Cause a Female-Specific Recognizable Syndrome with Developmental Delay and Congenital Malformations

Reijnders MR, Zachariadis V, Latour B, Jolly L, Mancini GM, Pfundt R, Wu KM, van Ravenswaaij-Arts CM, Veenstra-Knol HE, Anderlid BM, Wood SA, Cheung SW, Barnicoat A, Probst F, Magoulas P, Brooks AS, Malmgren H, Harila-Saari A, Marcelis CM, Vreeburg M, Hobson E, Sutton VR, Stark Z, Vogt J, Cooper N, Lim JY, Price S, Lai AH, Domingo D, Reversade B; DDD Study, Gecz J, Gilissen C, Brunner HG, Kini U, Roepman R, Nordgren A, Kleefstra T. De Novo Loss-of-Function Mutations in USP9X Cause a Female-Specific Recognizable Syndrome with Developmental Delay and Congenital Malformations. Am J Hum Genet. 2016 Feb 4;98(2):373-81.

PubMed ID: 
26833328

Progeroid Short Stature with Pigmented Nevi

Clinical Characteristics
Ocular Features: 

The presence of cataract has been reported.   One patient with keratoconus, endothelial dystrophy, and chronic conjunctivitis required a corneal transplant for a perforated ulcer.  Another individual with endothelial dystrophy, keratoconus, dry eye syndrome, and conjunctivitis developed OCT evidence of progressive retinal thickening and folding of inner retinal layers.  Retinal electrodiagnostic tests were normal.   Few patients have had complete ocular examinations, however.

Systemic Features: 

Short stature beginning in utero is characteristic and general growth parameters are usually in the third percentile.  The appearance of premature aging is suggested by a pinched bird-like facies and lack of facial subcutaneous fat.  Striking cutaneous pigmented nevi are present and may increase in number throughout life.  Joint mobility is limited to about half of normal.  The voice is often characteristically high-pitched.  Hypodontia and irregular dentition are often seen.

There may be an immunodeficiency as reflected by susceptibility to recurrent infections due to subnormal numbers of B and T cells.  Cognitive abilities are subnormal and some decline in adulthood has been reported.  Some individuals have been considered mentally retarded.  Agitation, touch hypersensitivity, depression, panic attacks, and severe insomnia may be present.  Sensorineural hearing loss is common.  Males may have hypospadias while females experience premature puberty and premature menopause.

Genetics

Consanguinity among some parents suggests autosomal recessive inheritance but no locus or mutation have been identified.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatnent has been reported.

References
Article Title: 

Takenouchi-Kosaki Syndrome

Clinical Characteristics
Ocular Features: 

The ocular phenotype consists of mild ptosis, synophrys, exotropia, and eversion of the lower eyelids.  One of two reported patients was described as having bilateral retinal dysplasia and a falciform retinal detachment in one eye.  Visual acuity is significantly impaired.

Systemic Features: 

Affected individuals may be of normal birth weight but skeletal growth is subnormal and there is general developmental delay.  Congenial cardiac anomalies such as persistent ductus arteriosus may be present.  Lymphedema has been noted at one year of age and probably persists throughout life.  Protein-losing enteropathy secondary to intestinal lymphangiectasia was present in one individual.  The same patient had pericardial effusion, hydrothorax, and ascites.  Intellectual disability may be severe although there is no evidence of progression.  Neurosensory hearing loss has been described in one patient.

Thrombocytopenia is a consistent finding and has been described as early as one year of age.  Platelet numbers as low as 52,000/microL have been recorded and appear larger than normal. 

Genetics

Both unrelated female patients reported have heterozygous missense mutations in the CDC42 gene (1p36). 

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

No treatment has been reported.

References
Article Title: 

Pseudohypoparathyroidism, Type 1A

Clinical Characteristics
Ocular Features: 

Cataracts and nystagmus are sometimes present.  Optic neuritis and papilledema have been reported and can result in optic atrophy.  The combination of cataracts and swelling of the optic nerves in children requires evaluation for hypocalcemia.

Systemic Features: 

The title refers to a group of conditions that have organ resistance to parathyroid hormone.  The phenotype is variable since there usually is a usually some degree of end-organ resistance to other hormones such as gonadotropins and TSH as in the PHP1A disorder described here.  The grouped clinical features are often referred to as Albright hereditary oseodystrophy or AHO.

Short stature with a short neck, a round face, chubby cheeks, and a depressed nasal bridge are usually present.  There may be cognitive deficits and some patients are considered to be mentally retarded.  The fourth and fifth metacarpals and sometimes metatarsals are characteristically short.   The teeth are late to erupt and can have an enamel deficit.  End organ resistance to other hormones may lead to signs of hypothyroidism and hypogonadism.  Calcification of subcutaneous tissues can result in palpable hard nodules and calcium deposition in basal ganglia and choroidal plexus may be demonstrable.  Some patients experience hypocalcemic tetany and seizures.  Hypocalcemia and hyperphosphatemia are often present along with elevated serum parathyroid hormone levels.

Genetics

This transmission pattern is likely modified by the effects of imprinting which also can modify the phenotype.  Mutltigenerational family patterns have an excess of maternal transmission.  The full phenotype is more likely expressed among maternally transmitted cases whereas partial or incomplete expression is more often seen among individuals who received the paternal allele. 

Heterozygous muttions in the GNAS1 gene (20q13.32) plays a role in this disease.  Signal transduction failure likely plays a major role in the failure of organs to respond to the appropriate hormone.

Several subtypes of pseudohypoparathyroidism have been reported but some do not have ocular signs.  However, type 1C (612462) patients can have cataracts and nystagmus with an almost identical phenotype to that of IA and may be the same condition.

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

Treatment focuses on normalization of calcium and phosphate serum levels.  A deficiency of vitamin D should also be corrected and has been reported to correct at least some of the lens opacities.  Cataract removal can be considered.

References
Article Title: 

Basel-Vanagaite-Smirin-Yosef Syndrome

Clinical Characteristics
Ocular Features: 

The eyes appear abnormally far apart.  Ptosis, microcornea, congenital cataracts, sparse eyebrows, and strabismus are usually present.  Epicanthal folds are often seen.

Systemic Features: 

Psychomotor development is severely delayed and with delay or absence of milestones.  DTRs are often hyperactive but some infants are described as hypotonic.  Some individuals have seizures.  There may be a nevus flammeus simplex lesion on the forehead and body hair is sparse.  Cleft palate, cardiac septal defects, hypospadius, thin corpus callosum and cerebral ventricular dilation have been observed.  The upper lip may have a tented morphology with everted lower lip vermilion. A short philtrum is common. 

Genetics

A homozygous missense mutation in the MED25 gene (19q13.33) has been reported and the transmission pattern is consistent with autosomal recessive inheritance.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No known treatment has been reported.

References
Article Title: 

Homozygous MED25 mutation implicated in eye-intellectual disability syndrome

Basel-Vanagaite L, Smirin-Yosef P, Essakow JL, Tzur S, Lagovsky I, Maya I, Pasmanik-Chor M, Yeheskel A, Konen O, Orenstein N, Weisz Hubshman M, Drasinover V, Magal N, Peretz Amit G, Zalzstein Y, Zeharia A, Shohat M, Straussberg R, Monte D, Salmon-Divon M, Behar DM. Homozygous MED25 mutation implicated in eye-intellectual disability syndrome. Hum Genet. 2015 Jun;134(6):577-87.

PubMed ID: 
25792360

PEHO Syndrome

Clinical Characteristics
Ocular Features: 

Optic atrophy is a common feature.  There may be lack of visual fixation from birth or sometimes several months later, attributed to cortical inattention.  Flash visual evoked potentials may be unrecordable. Pupillary responses to light are 'weak' and sluggish. Epicanthal folds may be seen.

Systemic Features: 

Infants are usually born with a normal head circumference but fall behind (2 SD or more) in the first year.  They have neonatal and infantile central hypotonia with brisk peripheral tendon reflexes during early childhood.  They are sometimes described as drowsy or lethargic.  Facial and limb edema can be extensive but transient sometimes and can disappear later in childhood.  The fingers are tapered.  The cheeks are full, the mouth is usually open and the upper lip appears 'tented'.  Global developmental delay is common and normal milestones are seldom attained.  Some patients have been described as severely retarded mentally.  Infantile spasms and myoclonic jerkingcan be seen within the first months of life while frank seizures with hypsarrhythmia are common in the first year of life.  Status epilepticus is a common occurrence.  General drowsiness and poor feeding are often features.  Death usually occurs in infancy or early childhood.  Midface hypoplasia and micrognathia are often present.

Brain imaging (MRI) and histology show severe alterations in myelination and cellular organization.  Neuronal loss is seen in the inner granular layer of the cerebellum but there is relative preservation of Purkinje cells.  General and progressive atrophy of the cerebellum and brain stem have been described.

Genetics

Homozygous frameshift mutations in ZNHIT3 (17q12) have been identified in affected members of several consanguineous families.  The presumed mutation seems to be most prevalent in Finland.

A somewhat similar disorder known as PEHO-like syndrome (617507) is the result of homozygous mutations in the CCDC88A gene.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

Physical therapy to prevent contractures and general supportive care can be helpful.  Supplemental feeding may be required. 

References
Article Title: 

The PEHO syndrome

Riikonen R. The PEHO syndrome. Brain Dev. 2001 Nov;23(7):765-9. Review.

PubMed ID: 
11701291

Mental Retardation, AD 34

Clinical Characteristics
Ocular Features: 

Patients may have upslanting lid fissures, epicanthus, ptosis, synophrys, and cortical visual impairment.

Systemic Features: 

Among the three reported individuals with the COL4A3BP mutation, one had postnatal microcephaly, widely spaced teeth, synophrys, and intellectual disability. Another had trunk hypotonia, global developmental delay, wide intermamillary distance, 2-3 toe syndactyly, tonic-clonic seizures, and myopathic facies. The third had a broad-based gait, coarse and curly hair, tonic-clonic seizures, and global developmental delay. 

Genetics

In a screening study of 1133 children with severe undiagnosed developmental conditions, three males were found with heterozygous mutations in the COL4A3BP gene (5q13).  Family history data are not given for these three individuals but autosomal dominant transmission seems to be a reasonable assumption.

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

Supportive care is required but no other treatment has been reported.

References
Article Title: 

Filippi Syndrome

Clinical Characteristics
Ocular Features: 

The ocular features have not been fully described.  The most consistent features are long eyelashes, thick (bushy) eyebrows, and 'visual disturbance'.  Most individuals have a facial dysmorphism which includes a broad nasal base suggestive of hypertelorism.  Optic atrophy and proptosis have been noted. 

Systemic Features: 

Intrauterine growth retardation is sometimes seen.  Microcephaly, short stature, syndactyly, intellectual disability (often labeled mental retardation), and a dysmorphic face are characteristic.  Some individuals have cryptorchidism, seizures, and ectodermal abnormalities including nail hypoplasia, hirsutism, and microdontia.  Mental and physical delays are common.  The syndactyly usually involves only soft tissue between toes 2, 3, and 4 and fingers 3 and 4 accompanied by clinodactyly of the 5th finger.  Polydactyly is sometimes present while radiologically the radial head may show evidence of hypoplasia. 

Genetics

Homozygosity or compound heterozygosity in the CKAP2L gene (2q13) segregates with this phenotype. 

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment is known.

References
Article Title: 

Mutations in CKAP2L, the human homolog of the mouse Radmis gene, cause Filippi syndrome

Hussain MS, Battaglia A, Szczepanski S, Kaygusuz E, Toliat MR, Sakakibara S, Altmuller J, Thiele H, Nurnberg G, Moosa S, Yigit G, Beleggia F, Tinschert S, Clayton-Smith J, Vasudevan P, Urquhart JE, Donnai D, Fryer A, Percin F, Brancati F, Dobbie A, Smigiel R, Gillessen-Kaesbach G, Wollnik B, Noegel AA, Newman WG, Nurnberg P. Mutations in CKAP2L, the human homolog of the mouse Radmis gene, cause Filippi syndrome. Am J Hum Genet. 2014 Nov 6;95(5):622-32.

PubMed ID: 
25439729

Epileptic Encephalopathy, Early Infantile 28

Clinical Characteristics
Ocular Features: 

Infants with this lethal neuropathy often have minimal or absent eye contact from birth.  Responses to visual stimuli are often but not always absent.  Optic atrophy may be present and the ERG is abnormal in some individuals. The retinas may have "abnormal" pigmentation while scotopic and photopic flash ERG responses are reduced as are visual evoked potentials indicating delayed visual maturation with severe macular and optic nerve dysfunction. 

Systemic Features: 

Seizures begin within weeks after birth and are resistant to pharmacological treatment.  There is no spontaneous motility and little or no psychomotor development.  Normal developmental milestones are usually not achieved.  Spasticity and hyperreflexia are often present but some newborn infants are hypotonic.  MRI imaging reveals cortical atrophy with hippocampal hypoplasia and a hypoplastic corpus callosum. Progressive microcephaly has been described.

Infants generally do not live beyond two years of age and may die within weeks or a few months. Pulmonary dysfunction can be a significant cause of morbidity. 

Genetics

The transmission pattern is consistent with autosomal recessive inheritance.  Homozygous and compound heterozygous mutations in the WWOX gene (16q23) have been found in several families.

Among the limited number of patients reported, at least two with compound heterozygous mutations had normal brain imaging, appropriate visual responses, and some ability to interact with their environment.  Profound psychomotor delays, however, remained.  Hypotonia replaced spasticity as a neurological feature in some infants.

The same gene is mutated in autosomal recessive spinocerebellar ataxia 12 (614322), a less severe condition in which gaze-evoked nystagmus occurs.

Other forms of epileptic encephalopathy have been reported (see 617105, 617106, and 617113) including Early Onset Epileptic Encephalopathy 48 (617276).  For an autosomal dominant form of epileptic encephalopathy in this database, see Epileptic Encephalopathy, Early Onset 47 (617166).

 

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment is known for this condition.

References
Article Title: 

WWOX-related encephalopathies: delineation of the phenotypical spectrum and emerging genotype-phenotype correlation

Mignot C, Lambert L, Pasquier L, Bienvenu T, Delahaye-Duriez A, Keren B, Lefranc J, Saunier A, Allou L, Roth V, Valduga M, Moustaine A, Auvin S, Barrey C, Chantot-Bastaraud S, Lebrun N, Moutard ML, Nougues MC, Vermersch AI, Heron B, Pipiras E, Heron D, Olivier-Faivre L, Gueant JL, Jonveaux P, Philippe C. WWOX-related encephalopathies: delineation of the phenotypical spectrum and emerging genotype-phenotype correlation. J Med Genet. 2015 Jan;52(1):61-70..

PubMed ID: 
25411445

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