Mental Retardation, AD 57

Clinical Characteristics
Ocular Features: 

Ptosis, strabismus, epicanthal folds, and upslanting lid fissures are often present but there is considerable variation among individuals.  Blepharophimosis, telecanthus, and various refractive errors have also been reported.

Systemic Features: 

There is great variability in the clinical signs among patients.  Most have developmental delays and intellectual disabilities combined with behavioral challenges such as anxiety, obsessive-compulsive disorders and features of autism spectrum disorders.  

Infants and young children may have feeding difficulties but may later develop constipation or diarrhea.  

Skeletal anomalies such as short stature, high palate, craniosynostosis, scoliosis, pes planus, hand contractures, and joint hypermobility have been reported.  The voice may be hoarse.

Genetics

Heterozygous mutations in the TLK2 gene (17q23) are responsible for this condition.

Treatment
Treatment Options: 

No treatment has been reported.

References
Article Title: 

De Novo and Inherited Loss-of-Function Variants in TLK2: Clinical and Genotype-Phenotype Evaluation of a Distinct Neurodevelopmental Disorder

Reijnders MRF, Miller KA, Alvi M, Goos JAC, Lees MM, de Burca A, Henderson A, Kraus A, Mikat B, de Vries BBA, Isidor B, Kerr B, Marcelis C, Schluth-Bolard C, Deshpande C, Ruivenkamp CAL, Wieczorek D; Deciphering Developmental Disorders Study, Baralle D, Blair EM, Engels H, Ludecke HJ, Eason J, Santen GWE, Clayton-Smith J, Chandler K, Tatton-Brown K, Payne K, Helbig K, Radtke K, Nugent KM, Cremer K, Strom TM, Bird LM, Sinnema M, Bitner-Glindzicz M, van Dooren MF, Alders M, Koopmans M, Brick L, Kozenko M, Harline ML, Klaassens M, Steinraths M, Cooper NS, Edery P, Yap P, Terhal PA, van der Spek PJ, Lakeman P, Taylor RL, Littlejohn RO, Pfundt R, Mercimek-Andrews S, Stegmann APA, Kant SG, McLean S, Joss S, Swagemakers SMA, Douzgou S, Wall SA, Kury S, Calpena E, Koelling N, McGowan SJ, Twigg SRF, Mathijssen IMJ, Nellaker C, Brunner HG, Wilkie AOM. De Novo and Inherited Loss-of-Function Variants in TLK2: Clinical and Genotype-Phenotype Evaluation of a Distinct Neurodevelopmental Disorder. Am J Hum Genet. 2018 Jun 7;102(6):1195-1203.

PubMed ID: 
29861108

Meta-analysis of 2,104 trios provides support for 10 new genes for intellectual disability

Lelieveld SH, Reijnders MR, Pfundt R, Yntema HG, Kamsteeg EJ, de Vries P, de Vries BB, Willemsen MH, Kleefstra T, Lohner K, Vreeburg M, Stevens SJ, van der Burgt I, Bongers EM, Stegmann AP, Rump P, Rinne T, Nelen MR, Veltman JA, Vissers LE, Brunner HG, Gilissen C. Meta-analysis of 2,104 trios provides support for 10 new genes for intellectual disability. Nat Neurosci. 2016 Sep;19(9):1194-6.

PubMed ID: 
27479843

References

Reijnders MRF, Miller KA, Alvi M, Goos JAC, Lees MM, de Burca A, Henderson A, Kraus A, Mikat B, de Vries BBA, Isidor B, Kerr B, Marcelis C, Schluth-Bolard C, Deshpande C, Ruivenkamp CAL, Wieczorek D; Deciphering Developmental Disorders Study, Baralle D, Blair EM, Engels H, Ludecke HJ, Eason J, Santen GWE, Clayton-Smith J, Chandler K, Tatton-Brown K, Payne K, Helbig K, Radtke K, Nugent KM, Cremer K, Strom TM, Bird LM, Sinnema M, Bitner-Glindzicz M, van Dooren MF, Alders M, Koopmans M, Brick L, Kozenko M, Harline ML, Klaassens M, Steinraths M, Cooper NS, Edery P, Yap P, Terhal PA, van der Spek PJ, Lakeman P, Taylor RL, Littlejohn RO, Pfundt R, Mercimek-Andrews S, Stegmann APA, Kant SG, McLean S, Joss S, Swagemakers SMA, Douzgou S, Wall SA, Kury S, Calpena E, Koelling N, McGowan SJ, Twigg SRF, Mathijssen IMJ, Nellaker C, Brunner HG, Wilkie AOM. De Novo and Inherited Loss-of-Function Variants in TLK2: Clinical and Genotype-Phenotype Evaluation of a Distinct Neurodevelopmental Disorder. Am J Hum Genet. 2018 Jun 7;102(6):1195-1203.

PubMedID: 29861108

Lelieveld SH, Reijnders MR, Pfundt R, Yntema HG, Kamsteeg EJ, de Vries P, de Vries BB, Willemsen MH, Kleefstra T, Lohner K, Vreeburg M, Stevens SJ, van der Burgt I, Bongers EM, Stegmann AP, Rump P, Rinne T, Nelen MR, Veltman JA, Vissers LE, Brunner HG, Gilissen C. Meta-analysis of 2,104 trios provides support for 10 new genes for intellectual disability. Nat Neurosci. 2016 Sep;19(9):1194-6.

PubMedID: 27479843