poor feeding

Mental Retardation, AD 53

Clinical Characteristics
Ocular Features: 

Dysmorphism of periocular structures includes downward slanting lid fissures, hypertelorism, and epicanthal folds.  Evidence for visual problems comes from visual tracking difficulties in some individuals.  Strabismus is present in a minority of patients.

Systemic Features: 

Delayed global development, cognitive impairment, and intellectual disability are major features of this form of mental retardation.  Hypotonia is present early.  Severe delays in onset of speech and walking are found in all patients and never develop in many individuals.  Behavior problems include, anxiety, hyperactivity, aggression, and autistic traits.  Feeding problems and breathing irregularities have been reported.  Seizures occur in some patients.

Brain MRIs are generally normal although corpus callosum anomalies are sometimes identified.

Genetics

Heterozygous mutations in the CAMK2A gene (5q32) have been found in individuals with this disorder.

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

No treatment for the general condition has been reported.

References
Article Title: 

De Novo Mutations in Protein Kinase Genes CAMK2A and CAMK2B Cause Intellectual Disability

Kury S, van Woerden GM, Besnard T, Proietti Onori M, Latypova X, Towne MC, Cho MT, Prescott TE, Ploeg MA, Sanders S, Stessman HAF, Pujol A, Distel B, Robak LA, Bernstein JA, Denomme-Pichon AS, Lesca G, Sellars EA, Berg J, Carre W, Busk OL, van Bon BWM, Waugh JL, Deardorff M, Hoganson GE, Bosanko KB, Johnson DS, Dabir T, Holla OL, Sarkar A, Tveten K, de Bellescize J, Braathen GJ, Terhal PA, Grange DK, van Haeringen A, Lam C, Mirzaa G, Burton J, Bhoj EJ, Douglas J, Santani AB, Nesbitt AI, Helbig KL, Andrews MV, Begtrup A, Tang S, van Gassen KLI, Juusola J, Foss K, Enns GM, Moog U, Hinderhofer K, Paramasivam N, Lincoln S, Kusako BH, Lindenbaum P, Charpentier E, Nowak CB, Cherot E, Simonet T, Ruivenkamp CAL, Hahn S, Brownstein CA, Xia F, Schmitt S, Deb W, Bonneau D, Nizon M, Quinquis D, Chelly J, Rudolf G, Sanlaville D, Parent P, Gilbert-Dussardier B, Toutain A, Sutton VR, Thies J, Peart-Vissers LELM, Boisseau P, Vincent M, Grabrucker AM, Dubourg C; Undiagnosed Diseases Network, Tan WH, Verbeek NE, Granzow M, Santen GWE, Shendure J, Isidor B, Pasquier L, Redon R, Yang Y, State MW, Kleefstra T, Cogne B; GEM HUGO; Deciphering Developmental Disorders Study, Petrovski S, Retterer K, Eichler EE, Rosenfeld JA, Agrawal PB, Bezieau S, Odent S, Elgersma Y, Mercier S. De Novo Mutations in Protein Kinase Genes CAMK2A and CAMK2B Cause Intellectual Disability. Am J Hum Genet. 2017 Nov 2;101(5):768-788.

PubMed ID: 
29100089

Neurodevelopmental Disorder, Mitochondrial, with Abnormal Movements and Lactic Acidosis

Clinical Characteristics
Ocular Features: 

Optic atrophy is sometimes present.  Nystagmus, and strabismus are seen in some patients.  A pigmentary retinopathy was found in one individual.

Systemic Features: 

This is a clinically heterogeneous disorder with extensive neurological deficits.  Patients have feeding and swallowing difficulties from the neonatal period.  There is intrauterine growth retardation and postnatally patients usually exhibit psychomotor delays and intellectual disabilities.  Some develop seizures and few achieve normal developmental milestones.  Axial hypotonia is present from early infancy and most patients have muscle weakness and atrophy.  However, there may be spastic quadriplegia which is often associated with dysmetria, tremor, and athetosis.  Ataxia eventually develops in most patients. 

Brain imaging shows cerebral and cerebellar atrophy, enlarged ventricles, white matter defects, and delayed myelination. 

Incomplete metabolic studies suggest there may be abnormalities in mitochondrial oxidative phosphorylation activity in at least some tissues.  Most patients have an elevated serum lactate.

Death in childhood is common.

Genetics

Homozygous and compound heterozygous mutations in the WARS2 gene have been found in several families with this condition.  The considerable variation in the phenotype may at least partially be explained by the fact that an additional variant in the W13G gene is sometimes present which impairs normal localization of the WARS2 gene product within mitochondria.

The transmission pattern in several families is consistent with autosomal recessive inheritance.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment has been reported for the general condition.

References
Article Title: 

Biallelic variants in WARS2 encoding mitochondrial tryptophanyl-tRNA synthase in six individuals with mitochondrial encephalopathy

Wortmann SB, Timal S, Venselaar H, Wintjes LT, Kopajtich R, Feichtinger RG, Onnekink C, Muhlmeister M, Brandt U, Smeitink JA, Veltman JA, Sperl W, Lefeber D, Pruijn G, Stojanovic V, Freisinger P, V Spronsen F, Derks TG, Veenstra-Knol HE, Mayr JA, Rotig A, Tarnopolsky M, Prokisch H, Rodenburg RJ. Biallelic variants in WARS2 encoding mitochondrial tryptophanyl-tRNA synthase in six individuals with mitochondrial encephalopathy. Hum Mutat. 2017 Dec;38(12):1786-1795.

PubMed ID: 
28905505

Combined Oxidative Phosphorylation Deficiency 32

Clinical Characteristics
Ocular Features: 

Ocular signs are common but variable.  Patients may not make eye contact and sometimes have disconjugate eye movements.  Strabismus (usually exotropia) and nystagmus or often present.

Systemic Features: 

Six patients from 4 unrelated families of mixed ethnic backgrounds have been reported.  Infants within the first 4 to 6 months of life had evidence of developmental delay and neurodevelopmental regression.  Poor feeding and breathing difficulties are often noted in this period.  Other later signs are axial hypotonia, abnormal movements such as tremor, spasticity, hyperkinetic movements, dystonia with eventual regression of milestones.  Joint contractures and kyphoscoliosis may develop. 

Microcephaly was noted in several infants and brain imaging in all patients reveals abnormal T2- weighted signals in the brainstem and specifically in the basal ganglia.  Decreased activity in muscle mitochondrial respiratory complexes I, III, and IV has been documented.  Lactate may be increased in serum and the CSF.  Postmortem studies show brain vascular proliferation and gliosis in basal structures.

Genetics

Homozygous or compound heterozygous mutations in MRPS34 (16p13.3) are the basis for this disorder.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment has been reported.

References
Article Title: 

Biallelic Mutations in MRPS34 Lead to Instability of the Small Mitoribosomal Subunit and Leigh Syndrome

Lake NJ, Webb BD, Stroud DA, Richman TR, Ruzzenente B, Compton AG, Mountford HS, Pulman J, Zangarelli C, Rio M, Bodaert N, Assouline Z, Sherpa MD, Schadt EE, Houten SM, Byrnes J, McCormick EM, Zolkipli-Cunningham Z, Haude K, Zhang Z, Retterer K, Bai R, Calvo SE, Mootha VK, Christodoulou J, Rotig A, Filipovska A, Cristian I, Falk MJ, Metodiev MD, Thorburn DR. Biallelic Mutations in MRPS34 Lead to Instability of the Small Mitoribosomal Subunit and Leigh Syndrome. Am J Hum Genet. 2017 Aug 3;101(2):239-254.

PubMed ID: 
28777931

Mitochondrial DNA Depletion Syndrome 3

Clinical Characteristics
Ocular Features: 

Nystagmus, disconjugate eye movements, and "optic dysplasia" have been noted.

Systemic Features: 

Infants feed poorly which is frequently associated with vomiting, failure to thrive, and growth delay.  They are hypothermic, hypoglycemic, and often jaundiced with signs of liver failure noted between birth and 6 months of age and death by approximately 1 year of age.  Hepatosplenomegaly is present early with abnormal liver enzymes, cholestasis, steatosis, and hepatocellular loss followed by cirrhosis with portal hypertension.  Metabolic acidosis, hyperbilirubinemia, hypoalbuminemia, and hypoglycemia are often present.  Mitochondrial DNA depletion in the liver approaches 84-90%.

All patients have encephalopathic signs with evidence of cerebral atrophy, microcephaly, hypotonia.  Hyperreflexia may be present and some infants have seizures.  Muscle tissue, however, has normal histology and respiratory chain activity.

Genetics

This disorder results from homozygous or compound heterozygous mutations in the DGUOK gene (2p13).

The same gene is mutated in PEOB4 (617070).

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

There is no effective treatment.  Liver transplantation in one infant was unsuccessful.  

References
Article Title: 

Congenital Disorder of Glycosylation, Type Ia

Clinical Characteristics
Ocular Features: 

Strabismus, roving eye movements (and nystagmus), and visual inattention are found in nearly all patients. Esotropia with defective abduction seems to be the most common oculomotor finding and may be present at birth.  Cataracts, ocular colobomas, oculomotor apraxia, disc pallor, and glaucoma have also been reported.  Vision is always subnormal. Reports of ocular disease before modern genotyping are not specific to the subtypes of CDG I now recognized.

This is a congenital, progressive disorder of photoreceptor degeneration with a later onset of progressive pigmentary retinopathy.  It is described in some cases as a typical retinitis pigmentosa.  The ERG is abnormal in all patients even if the pigmentary pattern is atypical for RP.  Rod responses are usually absent while the cone b-wave implicit time is delayed.  The degree of photoreceptor damage is variable, however.  Extended retinal function among younger patients suggest that the ‘on-pathway’ evolving synapses in the outer plexiform layer among photoreceptors, bipolar cells, and horizontal cells is severely dysfunctional.

Systemic Features: 

This is a multisystem disorder, often diagnosed in the neonatal period by the presence of severe encephalopathy with hypotonia, hyporeflexia, and poor feeding.  Failure to thrive, marked psychomotor retardation, delayed development, growth retardation, and ataxia become evident later in those who survive.  Cerebellar and brainstem atrophy with a peripheral neuropathy can be demonstrated during late childhood.  Some older patients have a milder disease, often with muscle atrophy and skeletal deformities such as kyphoscoliosis and a fusiform appearance of the digits.  Maldistribution of subcutaneous tissue is often seen resulting in some dysmorphism, especially of the face.  Hypogonadism and enlargement of the labia majora are commonly present.  Some patients have evidence of hepatic and cardiac dysfunction which together with severe infections are responsible for a 20% mortality rate in the first year of life.

Genetics

This is one of a group of genetically (and clinically) heterogeneous autosomal recessive conditions caused by gene mutations that result in enzymatic defects in the synthesis and processing of oligosaccharides onto glycoproteins. This type (Ia) is the most common.   The mutation lies in the PMM2 gene (16p13.2).

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

Most children require tube feeding with nutritional supplements.  The risk of systemic infections is high.  Those patients who survive into the second decade and beyond may require orthopedic procedures and are confined to wheelchairs.  Physical, occupational, and speech therapy along with parental support are important.

References
Article Title: 
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