feeding problems

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.

Pedigree: 
Autosomal dominant
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

Kabuki Syndrome 1

Clinical Characteristics
Ocular Features: 

The facial features and specifically the periocular anomalies are diagnostic and responsible for the eponymic designation (resembling the make-up of actors of a Japanese theatrical form known as Kabuki). The lid fissures are long and narrow and the lateral third of the lower lids are often everted.  The eyebrows are highly-arched and broad with some sparsity especially in the lateral portion.  The eyelashes are thick and ptosis is often noted. Strabismus may be present.  Blue sclerae have been reported.

Some patients may have extreme microphthalmia.

Systemic Features: 

Post-natal growth delay and short stature are present as a result of anomalies in the vertebrae often with secondary scoliosis.  Persistence of the fetal fingertip pads is common. Hypotonia and joint hypermobility have been noted and some degree of intellectual disability is common.  Seizures have been reported but these are not common. Cleft lip and palate are seen in about a third of patients and the palate is highly arched in about 75%.  The teeth are small, frequently malformed and widely spaced.  Feeding difficulties are common.  Anal anomalies such as imperforate anus, anovestibular fistulas, and an anteriorly placed opening may be present, especially in females.  A small penis, hypospadias, and cryptorchidism are common in males.

An ill-defined immune deficit seems to be a common feature as evident by susceptibility to infections, primarily otitis media in infants and later recurrent sinopulmonary infections.   The majority of patients have hypogammaglobulinemia with a variable pattern of antibody abnormalities resembling common variable immune deficiency and especially low levels of serum IgA.  

Hearing loss is seen in nearly half of patients, some of which is no doubt due to recurrent otitis media but CT radiography has demonstrated dysplastic morphology of inner ear structures and the petrous bone.  The ears are large and cupped and preauricular pits may be present as well.

Biliary atresia and a variety of morphological anomalies of the kidney have been reported.  Renal failure can occur.  Perhaps as many as 58% of patients have congenital heart defects, mostly septal in location. 

Genetics

Heterozygous mutations in KMT2D (12q13.12) (also called MLL2) are responsible for Kabuki syndrome 1 but parental transmission to offspring is rare and the majority of patients occur sporadically.  There is also an X-linked form (Kabuki 2) caused by mutations in KDM5A (Xp11.3).  Insufficient clinical data regarding the X-linked phenotype so far has precluded the ability to distinguish the two disorders without genotyping.

Residual genetic heterogeneity remains, however, as a substantial proportion of patients do not have mutations in the two mutant genes known.

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

There is no general treatment for this condition.  Management guidelines are available (Management of Kabuki Syndrome).

References
Article Title: 

MLL2 and KDM6A mutations in patients with Kabuki syndrome

Miyake N, Koshimizu E, Okamoto N, Mizuno S, Ogata T, Nagai T, Kosho T, Ohashi H, Kato M, Sasaki G, Mabe H, Watanabe Y, Yoshino M, Matsuishi T, Takanashi J, Shotelersuk V, Tekin M, Ochi N, Kubota M, Ito N, Ihara K, Hara T, Tonoki H, Ohta T, Saito K, Matsuo M, Urano M, Enokizono T, Sato A, Tanaka H, Ogawa A, Fujita T, Hiraki Y, Kitanaka S, Matsubara Y, Makita T, Taguri M, Nakashima M, Tsurusaki Y, Saitsu H, Yoshiura K, Matsumoto N, Niikawa N. MLL2 and KDM6A mutations in patients with Kabuki syndrome. Am J Med Genet A. 2013 Sep;161A(9):2234-43. 

PubMed ID: 
23913813

Canavan Disease

Clinical Characteristics
Ocular Features: 

Optic atrophy is the primary and perhaps only ocular manifestation of Canavan disease.  Acuity levels have not been reported but it has been noted that some infants and young children with early onset severe disease are able to track targets.  The ocular phenotype has not been well delineated.

Systemic Features: 

The clinical diagnosis of Canavan disease is suggested when the triad of hypotonia, macrocephaly and head lag is present.  It is a progressive form of spongy degeneration of the central nervous system but its onset, course, and severity are variable.

The disease is often evident before 6 months of age and survival is limited to a few months or years in infants with such early onset.  Such patients have the most severe and rapidly progressive disease.  It is noteworthy that, even though such infants do not achieve normal milestones such as sitting and standing, they do often interact socially by laughing, smiling, and reaching for objects.  Most young children are quiet and apathetic but some become irritable and develop spasticity as they grow.  CNS damage is evident as leukodystrophy on neuroimaging studies but this may not be present in later onset, milder forms of the disease.         

Other individuals may have a later and milder juvenile onset of symptoms and may present with delayed speech or motor development late in the first decade.  They often attend regular school but may benefit from tutoring and speech therapy.  They may live to adolescence or early adulthood.  Maldevelopment of the organ of Corti is responsible for hearing deficits in some children.

Genetics

Canavan disease is an autosomal recessive disorder resulting from homozygous or compound heterozygous mutations in the gene (ASPA) located at 17p13.2 encoding the enzyme aspartoacylase.  N-acetylaspartic acid (NAA) levels are usually elevated in urine.  However, because the levels of NAA can vary depending on the severity of clinical disease, gene testing provides a more reliable diagnosis. 

The carrier frequency is high among members of the Ashkenazi Jewish population.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

Antiepileptic drugs can be helpful.  Augmented feeding (gastric tubes)may be needed to maintain nutrition, while physical therapy and exercise may prevent contractures.  Speech therapy and low vision aids might be of benefit. Rare patients with a hearing deficit should be evaluated for possible benefit of hearing aids.

References
Article Title: 
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