Amish lethal microcephaly
General Information (adopted from Orphanet):
Synonyms, Signs: |
THIAMINE METABOLISM DYSFUNCTION SYNDROME 3 (MICROCEPHALY TYPE) AMISH LETHAL MICROCEPHALY MCPHA THMD3 |
Number of Symptoms | 45 |
OrphanetNr: | 99742 |
OMIM Id: |
607196
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ICD-10: |
Q02 |
UMLs: |
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MeSH: |
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MedDRA: |
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Snomed: |
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Prevalence, inheritance and age of onset:
Prevalence: | No data available. |
Inheritance: |
Autosomal recessive [Orphanet] |
Age of onset: |
Neonatal Infancy [Orphanet] |
Disease classification (adopted from Orphanet):
Parent Diseases: |
Syndrome with microcephaly as major feature
-Rare developmental defect during embryogenesis -Rare genetic disease -Rare neurologic disease |
Symptom Information:
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(HPO:0001992) | Organic aciduria | Very frequent [Orphanet] | 28 / 7739 | |||
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(HPO:0000253) | Progressive microcephaly | 37 / 7739 | ||||
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(HPO:0004331) | Decreased skull ossification | Occasional [Orphanet] | 31 / 7739 | |||
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(HPO:0100736) | Abnormality of the soft palate | Occasional [Orphanet] | 6 / 7739 | |||
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(HPO:0000277) | Abnormality of the mandible | Very frequent [Orphanet] | 394 / 7739 | |||
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(HPO:0000347) | Micrognathia | 426 / 7739 | ||||
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(HPO:0000252) | Microcephaly | Very frequent [Orphanet] | 832 / 7739 | |||
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(HPO:0000340) | Sloping forehead | Very frequent [Orphanet] | 86 / 7739 | |||
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(HPO:0001250) | Seizures | Occasional [Orphanet] | 1245 / 7739 | |||
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(HPO:0000737) | Irritability | 93 / 7739 | ||||
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(HPO:0100851) | Abnormal emotion/affect behavior | Very frequent [Orphanet] | 85 / 7739 | |||
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(HPO:0001276) | Hypertonia | Frequent [Orphanet] | 317 / 7739 | |||
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(HPO:0002509) | Limb hypertonia | 13 / 7739 | ||||
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(HPO:0001371) | Flexion contracture | 220 / 7739 | ||||
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(HPO:0001387) | Joint stiffness | Occasional [Orphanet] | 322 / 7739 | |||
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(HPO:0004349) | Reduced bone mineral density | Frequent [Orphanet] | 165 / 7739 | |||
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(HPO:0002414) | Spina bifida | Frequent [Orphanet] | 47 / 7739 | |||
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(HPO:0001557) | Prenatal movement abnormality | Occasional [Orphanet] | 16 / 7739 | |||
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(HPO:0002240) | Hepatomegaly | Occasional [Orphanet] | 467 / 7739 | |||
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(HPO:0004325) | Decreased body weight | Very frequent [Orphanet] | 492 / 7739 | |||
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(HPO:0003128) | Lactic acidosis | 116 / 7739 | ||||
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(HPO:0004360) | Abnormality of acid-base homeostasis | Very frequent [Orphanet] | 5 / 7739 | |||
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(HPO:0001252) | Muscular hypotonia | Frequent [Orphanet] | 990 / 7739 | |||
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(HPO:0008936) | Muscular hypotonia of the trunk | 77 / 7739 | ||||
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(HPO:0000007) | Autosomal recessive inheritance | 2538 / 7739 | ||||
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(HPO:0003577) | Congenital onset | 133 / 7739 | ||||
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(HPO:0007370) | Aplasia/Hypoplasia of the corpus callosum | Frequent [Orphanet] | 180 / 7739 | |||
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(OMIM) | Increased urinary 2-ketoglutarate (variable) | 1 / 7739 | ||||
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(OMIM) | Increased urinary lactate | 4 / 7739 | ||||
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(OMIM) | Absence of anterior and posterior fontanelles | 1 / 7739 | ||||
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(HPO:0002536) | Abnormal cortical gyration | Frequent [Orphanet] | 72 / 7739 | |||
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(HPO:0012795) | Abnormality of the optic disc | Very frequent [Orphanet] | 187 / 7739 | |||
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(OMIM) | No psychomotor development | 1 / 7739 | ||||
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(OMIM) | Lactic acidosis during infection | 1 / 7739 | ||||
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(OMIM) | Hepatomegaly associated with infection | 1 / 7739 | ||||
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(OMIM) | Microcephaly, extreme | 1 / 7739 | ||||
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(HPO:0001321) | Cerebellar hypoplasia | 114 / 7739 | ||||
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(OMIM) | Nearly absent cranial vault | 1 / 7739 | ||||
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(HPO:0012758) | Neurodevelopmental delay | Very frequent [Orphanet] | 949 / 7739 | |||
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(OMIM) | Immature brain with no gyral development | 1 / 7739 | ||||
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(HPO:0002334) | Abnormality of the cerebellar vermis | Very frequent [Orphanet] | 137 / 7739 | |||
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(HPO:0001522) | Death in infancy | Very frequent [Orphanet] | 275 / 7739 | |||
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(OMIM) | Hypoplastic pons | 1 / 7739 | ||||
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(HPO:0002119) | Ventriculomegaly | Frequent [Orphanet] | 253 / 7739 | |||
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(HPO:0001338) | Partial agenesis of the corpus callosum | 22 / 7739 |
Associated genes:
ClinVar (via SNiPA)
Gene symbol | Variation | Clinical significance | Reference |
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Additional Information:
Description: (OMIM) |
Amish type microcephaly is a severe autosomal recessive metabolic disorder characterized by severe microcephaly apparent at birth, profoundly delayed psychomotor development, brain malformations, and episodic encephalopathy associated with lactic acidosis and alpha-ketoglutaric aciduria (summary by Kelley et al., ... |
Clinical Description OMIM |
Kelley et al. (2002) described a metabolic disorder among the Old Order Amish of Lancaster County, Pennsylvania, characterized by severe congenital microcephaly, death within the first year, and severe 2-ketoglutaric aciduria. The disorder segregated as an autosomal recessive ... |
Molecular genetics OMIM |
Rosenberg et al. (2002) identified a list of positional candidate genes, comprising 7 full-length cDNAs, 3 EST clusters, and 11 predicted genes. The authors reasoned that because alpha-ketoglutarate is a component of the Krebs cycle, the alpha-ketoglutarate abnormality ... |
Diagnosis GeneReviews | The major clinical finding in individuals with Amish lethal microcephaly (MCPHA) is severe microcephaly present at birth [Kelley et al 2002]. Occipitofrontal circumference (OFC) is typically six to 12 standard deviations below the mean. ... Gene SymbolTest MethodMutations DetectedMutation Detection Frequency 1Test AvailabilitySLC25A19Sequence analysis | c.530G>C and other sequence variants 2100% 3ClinicalDeletion / duplication analysis 4Deletion / duplication of one or more exons or the whole gene 5Unknown; none reported to date1. The ability of the test method used to detect a mutation that is present in the indicated gene2. Examples of mutations detected by sequence analysis may include small intragenic deletions/insertions and missense, nonsense, and splice site mutations; typically, exonic or whole-gene deletions/duplications are not detected.3. Note that the 100% mutation detection rate is for testing among the Amish; the yield would be expected to be lower in non-Amish individuals.4. Testing that identifies deletions/duplications not readily detectable by sequence analysis of the coding and flanking intronic regions of genomic DNA; included in the variety of methods that may be used are: quantitative PCR, long-range PCR, multiplex ligation-dependent probe amplification (MLPA), and chromosomal microarray (CMA) that includes this gene/chromosome segment.5. No deletions or duplications involving SLC25A13 as causative of Amish lethal microcephaly have been reported. (Note: By definition, deletion/duplication analysis identifies rearrangements that are not identifiable by sequence analysis of genomic DNA.)Interpretation of test results. For issues to consider in interpretation of sequence analysis results, click here.Information on specific allelic variants may be available in the Molecular Genetics section (see Table A and/or Molecular Genetics, Pathologic allelic variants).Testing StrategyTo confirm/establish the diagnosis in a proband. Perform molecular genetic testing to identify disease-causing mutations using sequence analysis.Carrier testing for at-risk relatives requires prior identification of the disease-causing mutations in the family.Note: Carriers are heterozygotes for this autosomal recessive disorder and are not at risk of developing the disorder.Prenatal diagnosis and preimplantation genetic diagnosis (PGD) for at-risk pregnancies require prior identification of the disease-causing mutations in the family.Genetically Related (Allelic) DisordersSpiegel et al [2009] reported four sibs, the offspring of consanguineous Arab-Muslim parents, with a homozygous c.373G>A mutation which predicts p.Gly125Ser. They all had the similar and distinctive presentation of acute encephalopathy, striatal necrosis, lactic acidosis, and slowly progressive peripheral neuropathy. This phenotype appears to be distinct from Amish microcephaly: the affected individuals were normocephalic and had childhood onset of metabolic decompensation with permanent neurologic sequelae. The sibs did not have elevated urinary 2-ketoglutarate but did have elevated plasma concentrations of lactate. No pathology was available.
Clinical Description GeneReviews | Amish lethal microcephaly (MCPHA) is a distinct disorder with little variability in its presentation, at least among the Old Order Amish from Lancaster County, Pennsylvania [Kelley et al 2002]. Affected infants have severe microcephaly at birth. The cranial vault is extremely underdeveloped as a result of the small brain size. Anterior and posterior fontanels are closed, and ridging from premature sutural fusion may be evident. The facial features are distorted as a result of the profound microcephaly. The only non-CNS physical anomaly is moderate micrognathia. Mild hepatomegaly has been observed in several affected individuals, usually during acute illnesses associated with metabolic acidosis.... |
Differential Diagnosis GeneReviews | Microcephaly has a wide variety of causative factors. It can be syndromic or isolated, environmental or genetic, congenital or acquired [Battaglia & Carey 2003]. A metabolic screen (including urine organic acids, plasma amino acids, lactate, pyruvate, and electrolytes) is indicated for all children with congenital microcephaly. Further specific evaluations are performed as indicated based on the results of this screen.... |
Management GeneReviews | To establish the extent of disease in an individual diagnosed with Amish lethal microcephaly (MCPHA), appropriate imaging studies should be performed. Refer to general references on microcephaly for guidance; no recommendations are specific to MCPHA.... |
Molecular genetics GeneReviews |
Information in the Molecular Genetics and OMIM tables may differ from that elsewhere in the GeneReview: tables may contain more recent information. —ED.... Gene SymbolChromosomal LocusProtein NameLocus SpecificHGMDSLC25A1917q25 | Mitochondrial thiamine pyrophosphate carrierSLC25A19 homepage - Mendelian genesSLC25A19Data are compiled from the following standard references: gene symbol from HGNC; chromosomal locus, locus name, critical region, complementation group from OMIM; protein name from UniProt. For a description of databases (Locus Specific, HGMD) to which links are provided, click here.Table B. OMIM Entries for Amish Lethal Microcephaly (View All in OMIM) View in own window 606521SOLUTE CARRIER FAMILY 25 (MITOCHONDRIAL THIAMINE PYROPHOSPHATE CARRIER), MEMBER 19; SLC25A19 607196MICROCEPHALY, AMISH TYPE; MCPHANormal allelic variants. SLC25A19 contains nine exons that span 16.5 kb [Iacobazzi et al 2001]. Translation begins in exon 4 and there is evidence of alternate splicing of the three untranslated 5’ exons.Pathologic allelic variants. One known genetic alteration results in Amish lethal microcephaly (MCPHA) [Rosenberg et al 2002]. A single-nucleotide substitution that predicts p.Gly177Ala (see Table 2; OMIM 606521) was found in homozygous form in affected individuals. This substitution was not found in 252 chromosomes from non-Amish individuals tested by a PCR-amplified restriction fragment length polymorphism assay. (For more information, see Table A.)Table 2. Selected SLC25A19 Pathologic Allelic VariantsView in own windowDNA Nucleotide Change Protein Amino Acid Change Reference Sequencesc.530G>Cp.Gly177AlaNM_021734