Failure to thrive, and Gait ataxia

Yuan-Harel-Lupski syndrome is a complex neurodevelopmental disorder characterized by global developmental delay and early-onset peripheral neuropathy. The disorder comprises features of both demyelinating Charcot-Marie-Tooth disease type 1A (CMT1A ), which results from duplication of the PMP22 gene on 17p12, and Potocki-Lupski syndrome (PTLS ), which results from duplication of a slightly proximal region on 17p11.2 that includes the RAI1 gene. These 2 loci are about 2.5 Mb apart. The resultant YUHAL phenotype may be more severe in comparison to the individual contributions of each gene, with particularly early onset of peripheral neuropathy and features of both central and peripheral nervous system involvement (summary by Yuan et al., 2015).

PMP22-RAI1 CONTIGUOUS GENE DUPLICATION SYNDROME Is also known as trisomy 17p11.2-p12|dup(17)(p11.2p12)|trisomy 17p11.2p12|yuan-harel-lupski syndrome|17p11.2p12 microduplication syndrome

• Intellectual disability
• Global developmental delay
• Generalized hypotonia
• Failure to thrive
• Strabismus

SOURCES: OMIM ORPHANET MENDELIAN

Mitochondrial DNA depletion syndrome-8A is a severe autosomal recessive disorder characterized by neonatal hypotonia, lactic acidosis, and neurologic deterioration. Renal tubular involvement may also occur (Bourdon et al., 2007).Mitochondrial DNA depletion syndrome-8B is characterized by ophthalmoplegia, ptosis, gastrointestinal dysmotility, cachexia, peripheral neuropathy, and brain MRI changes, known as the MNGIE phenotype (Shaibani et al., 2009).For a discussion of genetic heterogeneity of mtDNA depletion syndromes, see MTDPS1 (OMIM ).

MITOCHONDRIAL DNA DEPLETION SYNDROME, ENCEPHALOMYOPATHIC FORM WITH RENAL TUBULOPATHY Is also known as mitochondrial dna depletion syndrome, encephalomyopathic, with renal tubulopathy, autosomal recessive|mtdna depletion syndrome, encephalomyopathic form with renal tubulopathy

• Intellectual disability
• Seizures
• Generalized hypotonia
• Hearing impairment
• Failure to thrive

SOURCES: ORPHANET OMIM MENDELIAN

SULFITE OXIDASE DEFICIENCY, ISOLATED; ISOD Is also known as sulfocysteinuria

• Seizures
• Global developmental delay
• Generalized hypotonia
• Ataxia
• Failure to thrive

SOURCES: ORPHANET MESH OMIM MENDELIAN

SeSAME syndrome is characterized by seizures, sensorineural deafness, ataxia, intellectual deficit, and electrolyte imbalance (hypokalemia, metabolic alkalosis, and hypomagnesemia).

EAST SYNDROME Is also known as sesame syndrome|epilepsy-ataxia-sensorineural deafness-tubulopathy syndrome|seizures-sensorineural deafness-ataxia-intellectual disability-electrolyte imbalance syndrome|east syndrome|epilepsy, ataxia, sensorineural deafness, and tubulopathy

• Intellectual disability
• Seizures
• Global developmental delay
• Short stature
• Generalized hypotonia

SOURCES: MESH ORPHANET OMIM MENDELIAN

MRXSB is an X-linked dominant neurodevelopmental disorder characterized by delayed psychomotor development, intellectual disability with behavioral abnormalities, and dysmorphic facial features. Additional variable features include musculoskeletal abnormalities, seizures, acquired microcephaly, and feeding problems with poor overall growth. Only females are affected (summary by Bain et al., 2016).

• Intellectual disability
• Seizures
• Global developmental delay
• Short stature
• Generalized hypotonia

SOURCES: OMIM MENDELIAN

NDHMSD is a severe neurodevelopmental disorder characterized by profound developmental delay, severe intellectual disability with absent speech, muscular hypotonia, and a hyperkinetic movement disorder. Additional features may include cortical blindness, generalized cerebral atrophy, and seizures (summary by Lemke et al., 2016).

NEURODEVELOPMENTAL DISORDER WITH OR WITHOUT HYPERKINETIC MOVEMENTS AND SEIZURES, AUTOSOMAL DOMINANT; NDHMSD Is also known as mrd8, formerly|mental retardation, autosomal dominant 8, formerly

• Intellectual disability
• Seizures
• Global developmental delay
• Generalized hypotonia
• Microcephaly

SOURCES: OMIM MENDELIAN

• Intellectual disability
• Seizures
• Global developmental delay
• Short stature
• Microcephaly

SOURCES: OMIM MENDELIAN

HSD10 mitochondrial disease most commonly presents as an X-linked neurodegenerative disorder with highly variable severity and age at onset ranging from the neonatal period to early childhood. The features are usually multisystemic, consistent with mitochondrial dysfunction. Some affected males have a severe infantile form associated with cardiomyopathy that may result in death in early childhood, whereas other rare patients may have juvenile onset or even atypical presentations with normal neurologic development. More severely affected males show developmental regression in infancy or early childhood, often associated with early-onset intractable seizures, progressive choreoathetosis and spastic tetraplegia, optic atrophy or retinal degeneration resulting in visual loss, and mental retardation. Heterozygous females may show non-progressive developmental delay and intellectual disability, but may also be clinically normal. Although the diagnosis can be aided by the observation of increased urinary levels of metabolites of isoleucine breakdown (2-methyl-3 hydroxybutyrate and tiglylglycine), there is not a correlation between these laboratory features and the phenotype. In addition, patients do not develop severe metabolic crises in the neonatal period as observed in other organic acidurias, but may show persistent lactic acidosis, most likely reflecting mitochondrial dysfunction (summary by Rauschenberger et al., 2010; review by Zschocke, 2012).In a review of the disorder, Zschocke (2012) noted that although this disorder was originally thought to be an inborn error of branched-chain fatty acid and isoleucine metabolism resulting from decreased HSD17B10 dehydrogenase activity (HSD17B10 'deficiency'), subsequent studies have shown that the HSD17B10 gene product has additional functions and also acts as a component of the mitochondrial RNase P holoenzyme, which is involved in mitochondrial tRNA processing and maturation and ultimately mitochondrial protein synthesis. The multisystemic features of HSD10MD most likely result from the adverse effect of HSD17B10 mutations on mitochondrial function, rather than from the effects on the dehydrogenase activity (see PATHOGENESIS below).

HSD10 MITOCHONDRIAL DISEASE; HSD10MD Is also known as hsd17b10 deficiency|mhbd deficiency|2-methyl-3-hydroxybutyryl-coa dehydrogenase deficiency|camr|mental retardation with chorioathetosis and abnormal behavior|mental retardation, x-linked, syndromic 10|17-beta-hydroxysteroid dehydrogenase x deficiency|chor

• Intellectual disability
• Seizures
• Global developmental delay
• Generalized hypotonia
• Hearing impairment

SOURCES: ORPHANET OMIM MENDELIAN

Oliver-McFarlane syndrome is a rare congenital disorder characterized by trichomegaly, severe chorioretinal atrophy and multiple pituitary hormone deficiencies, including growth hormone (GH ), gonadotropins (see {118860}), and thyroid-stimulating hormone (TSH; see {118850}). Thyroid and GH abnormalities may be present at birth and, if untreated, result in intellectual impairment and profound short stature. Congenital hypogonadism occurs in half of patients, and nearly all have documented hypogonadotropic hypogonadism during puberty, with subsequent reproductive dysfunction. Chorioretinal atrophy is typically noted in the first 5 years of life. Half of reported cases have spinocerebellar involvement, including ataxia, spastic paraplegia, and peripheral neuropathy (summary by Hufnagel et al., 2015).Laurence-Moon syndrome (OMIM ) is an allelic disorder with overlapping features.

OLIVER-MCFARLANE SYNDROME; OMCS Is also known as eyelashes, long, with mental retardation|trichomegaly with mental retardation, dwarfism, and pigmentary degeneration of retina

• Intellectual disability
• Short stature
• Ataxia
• Growth delay
• Nystagmus

SOURCES: OMIM MENDELIAN

DLD deficiency is an autosomal recessive metabolic disorder characterized biochemically by a combined deficiency of the branched-chain alpha-keto acid dehydrogenase complex (BCKDC), pyruvate dehydrogenase complex (PDC), and alpha-ketoglutarate dehydrogenase complex (KGDC). This is the result of E3 being a common component of all 3 mitochondrial multienzyme complexes. Clinically, affected individuals have lactic acidosis and neurologic deterioration due to sensitivity of the central nervous system to defects in oxidative metabolism. E3 deficiency is often associated with increased urinary excretion of alpha-keto acids, such as pyruvate (summary by Hong et al., 1996). E3 deficiency can also be associated with increased concentrations of branched-chain amino acids, as observed in maple syrup urine disease (MSUD ), and is sometimes referred to as 'MSUD type III,' although patients with E3 deficiency have additional biochemical defects (Chuang and Shih, 2001; Robinson, 2001).

DIHYDROLIPOAMIDE DEHYDROGENASE DEFICIENCY; DLDD Is also known as maple syrup urine disease, type iii|e3 deficiency|lipoamide dehydrogenase deficiency, lactic acidosis due to|dld deficiency

• Seizures
• Global developmental delay
• Generalized hypotonia
• Hearing impairment
• Microcephaly

SOURCES: OMIM MENDELIAN