At conception, each sib of an affected individual has a 25% chance of being affected, a 50% chance of being an asymptomatic carrier, and a 25% chance of being unaffected and not a carrier. [ncbi.nlm.nih.gov]

Showing of 33 80%-99% of people have these symptoms Cerebellar vermis hypoplasia 0001320 Death in infancy Infantile death Lethal in infancy [ more ] 0001522 Feeding difficulties Feeding problems Poor feeding [ more ] 0011968 Irritability Irritable 0000737 [rarediseases.info.nih.gov]

[…] muscle weakness Thoracic kyphosis Facial diplegia Nemaline bodies Slender build Myokymia Distal lower limb muscle weakness Hypoplasia of the musculature Heterogeneous Pectus excavatum Rapidly progressive Intracranial hemorrhage Acrania Triangular face Death [mendelian.co]

Showing of 33 80%-99% of people have these symptoms Cerebellar vermis hypoplasia 0001320 Death in infancy Infantile death Lethal in infancy [ more ] 0001522 Feeding difficulties Feeding problems Poor feeding [ more ] 0011968 Irritability Irritable 0000737 [rarediseases.info.nih.gov]

They may also have an unusually small lower jaw and chin (micrognathia) and an enlarged liver (hepatomegaly). Affected infants may have seizures and difficulty maintaining their body temperature. [ghr.nlm.nih.gov]

[…] have these symptoms Cleft soft palate 0000185 Decreased fetal movement Less than 10 fetal movements in 12 hours 0001558 Decreased skull ossification Decreased bone formation of skull 0004331 Generalized tonic-clonic seizures Grand mal seizures 0002069 Hepatomegaly [rarediseases.info.nih.gov]

Mild hepatomegaly has been observed in several affected individuals, usually during acute illnesses associated with metabolic acidosis. 2-ketoglutaric acidosis has been demonstrated in a number of Amish infants with this disorder (a variable finding). [ncbi.nlm.nih.gov]

Myopathic facies Generalized muscle weakness Muscular dystrophy Ventriculomegaly Strabismus Epileptic encephalopathy Progressive neurologic deterioration Hepatic failure Elevated hepatic transaminase Respiratory failure Hypoplasia of the corpus callosum Hepatomegaly [mendelian.co]

0001376 Percent of people who have these symptoms is not available through HPO Autosomal recessive inheritance 0000007 Cerebellar hypoplasia Small cerebellum Underdeveloped cerebellum [ more ] 0001321 Congenital onset Symptoms present at birth 0003577 Flexion [rarediseases.info.nih.gov]

Limited joint mobility Limited joint motion [ more ] 0001376 Percent of people who have these symptoms is not available through HPO Autosomal recessive inheritance 0000007 Cerebellar hypoplasia Small cerebellum Underdeveloped cerebellum [ more ] 0001321 [rarediseases.info.nih.gov]

Showing of 33 80%-99% of people have these symptoms Cerebellar vermis hypoplasia 0001320 Death in infancy Infantile death Lethal in infancy [ more ] 0001522 Feeding difficulties Feeding problems Poor feeding [ more ] 0011968 Irritability Irritable 0000737 [rarediseases.info.nih.gov]

The single affected individual described by Siu et al [2010] had irritability and profound developmental delay. The Amish patients were able to breast/bottle feed early on, but developed severe irritability and seizures. [ncbi.nlm.nih.gov]

Often they become very irritable starting in the second or third month of life. [ghr.nlm.nih.gov]

Case studies report that the infant has seizures early on, is cold all the time, becomes irritable at ages 12 - 16 weeks, and dies before the age of one year. [owlcation.com]

Physical therapy may alleviate contractures or other secondary neurologic manifestations. Infectious illnesses are managed to minimize acidosis. GENETIC COUNSELING: Amish lethal microcephaly is inherited in an autosomal recessive manner. [ncbi.nlm.nih.gov]

tonic-clonic seizures Grand mal seizures 0002069 Hepatomegaly Enlarged liver 0002240 Limitation of joint mobility Decreased joint mobility Decreased mobility of joints Limited joint mobility Limited joint motion [ more ] 0001376 Percent of people who [rarediseases.info.nih.gov]

tonic-clonic seizures Developmental regression Limb muscle weakness Spastic paraplegia Abnormality of movement Peripheral axonal neuropathy Cirrhosis Hip dislocation Focal seizures Paralysis Neuronal loss in central nervous system Neurodegeneration Memory [mendelian.co]

Troyer Syndrome - progressive spastic paraparesis (lower limb paralysis), dysarthria (leads to difficulty in speaking), and pseudobulbar palsy (inability to control facial movements); distal amyotrophy (muscle atrophy); motor and cognitive developmental [owlcation.com]