IHPRF2

Hypotonia, Infantile, with Psychomotor Retardation And Characteristic Facies 2

Clinical Characteristics
Ocular Features: 

Anomalies of periocular structures are part of the characteristic facial morphology.  The lid fissures slant downward and epicanthal folds are with ptosis are generally present.  Strabismus and nystagmus are characteristic features.

Systemic Features: 

This is a severe congenital neurodevelopmental disorder with global delay, hypotonia, and characteristic facies.  It is usually present at birth and soon manifest as a profound intellectual delay.  Most patients do not develop speech or independent motor skills.  Feeding difficulties are evident early and often require gastric tube placement for nutrition.  Failure to thrive is common.   Most patients have seizures of a tonic-clonic or atonic type which may be controlled with medication. 

Microcephaly, brachycephaly, plagiocephaly, and brachycephaly have been described.  A high forehead with frontal bossing, facial hypotonia, triangular facies have been described.  The ears are low-set and posteriorly rotated.  The upper lip is often thin and the mouth is commonly open.  The neck appears short, the nose is bulbous while the nasal bridge is prominent and the nares may be anteverted.

Brain imaging is normal in some patients but there is evidence of generalized cerebral atrophy, with a thin corpus callosum and decreased myelination in others.  Variable features such as scoliosis, hip contractures, muscle wasting, and dyskinesias are sometimes seen.

Genetics

This disorder is caused by homozygous or compound heterozygous mutations in the UNC80 gene (2q34).  

For somewhat similar disorders see IHPRF1 (615419) and IHPRF3 (616900).

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment has been reported.

References
Article Title: 

Biallelic Mutations in UNC80 Cause Persistent Hypotonia, Encephalopathy, Growth Retardation, and Severe Intellectual Disability

Stray-Pedersen A, Cobben JM, Prescott TE, Lee S, Cang C, Aranda K, Ahmed S, Alders M, Gerstner T, Aslaksen K, Tetreault M, Qin W, Hartley T, Jhangiani SN, Muzny DM, Tarailo-Graovac M, van Karnebeek CD; Care4Rare Canada Consortium; Baylor-Hopkins Center for Mendelian Genomics, Lupski JR, Ren D, Yoon G. Biallelic Mutations in UNC80 Cause Persistent Hypotonia, Encephalopathy, Growth Retardation, and Severe Intellectual Disability. Am J Hum Genet. 2016 Jan 7;98(1):202-9.

PubMed ID: 
26708751

UNC80 mutation causes a syndrome of hypotonia, severe intellectual disability, dyskinesia and dysmorphism, similar to that caused by mutations in its interacting cation channel NALCN

Perez Y, Kadir R, Volodarsky M, Noyman I, Flusser H, Shorer Z, Gradstein L, Birnbaum RY, Birk OS. UNC80 mutation causes a syndrome of hypotonia, severe intellectual disability, dyskinesia and dysmorphism, similar to that caused by mutations in its interacting cation channel NALCN. J Med Genet. 2016 Jun;53(6):397-402.

PubMed ID: 
26545877
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