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Trismus-Pseudocamptodactyly Syndrome: MYH8 Sequencing

Alternate test name

Distal Arthrogryposis type 7; Hecht syndrome

Gene name / Alternate gene name
  • MYH8
Myosin heavy chain 8
Lab area
Genome Diagnostics - Molecular Genetics
Method and equipment
Expected turn-around time
Pregnancy/STAT: 2-3 weeks Routine: 4-6 weeks
Specimen type

Blood; gDNA.

For details about specimen requirements, please refer to: Specimen Type & Requirements (PDF).

Specimen requirements
  • Blood: 5-10 mL in EDTA, 0.5 mL in EDTA (neonate); 
  • DNA-minimum 10 ug in 100 uL low TE (pH8.0)
Storage and transportation

Room Temperature

For details about specimen requirements, please refer to: Specimen Type and Requirements

Special requirements

Special Instructions for Genome Diagnostics Samples

If sample shipment >48 hours, ship on ice.

Shipping information
The Hospital for Sick Children
Division of Genome Diagnostics
555 University Avenue, Black Wing, Room 3416
Toronto, ON
M5G 1X8
Phone: 416-813-7200 ext. 2
Hours: Monday to Friday, 8 a.m. to 4:30 p.m.
Off hours: Please send to Rapid Response Laboratory, 555 University Avenue, Room 3642
Email Molecular Lab:
Email Cytogenetics:
Background and clinical significance

Patients with trismus-pseudocamptodactyly syndrome may show cardiac myxomas, spotty skin pigmentation alone or in combination with cutaneous lesions. Most affected individuals have distal arthrogryposis, including pseudocamptodactyly of the hands and feet, trismus, or both, which improves symptomatically with aging.

Trismus-pseudocamptodactyly syndrome is an autosomal dominant disorder caused by a deficiency of a perinatal skeletal myosin heavy chain. The syndrome is caused by mutations in the MYH8 gene which has been mapped to chromosome 17p13.1. A single mutation, p.Arg674Gln, has been described in several families of Belgian descent.

Trismus-pseudocamptodactyly syndrome is present when an individual has one copy of the defective gene. There is a 50% chance that baby will inherit the mutation for trismus-pseudocamptodactyly syndrome and thus may develop symptoms in the perinatal period. There is a 50% chance that the baby will not have trismus-pseudocamptodactyly syndrome.

See related information sheet:  Trismus-pseudocamptodactyly syndrome

Disease condition

Trismus-Pseudocamptodactyly Syndrome

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