Case2: female, 16 years old

DiseaseAssertion: Myopathy

FamilyInfo:

CasePresentingHPOs: HP:0040083, HP:0002650, HP:0003722, HP:0001371, HP:0009027, HP:0012515

"Toe walking, Scoliosis, Neck flexor weakness, Flexion contractures, Foot dorsiflexor weakness, Hip flexor weakness"

CaseHPOFreeText: Presented with toe-walking at age 5 years and required bilateral tendo-Achilles releases at ages 7 and 13 years. A progressive scoliosis required surgical stabilization at age 12 years. At age 13 years neck movements were markedly restricted in all directions except extension, and there were mild flexion contractures at the hips, knees and ankles. There was marked neck flexion weakness, moderate weakness of hip extension and ankle dorsiflexion, and mild weakness of shoulder abduction, hip flexion and knee flexion/extension. While walking her upper body was angled forward, there was external rotation of the feet and mild foot-drop. The axial involvement in this case largely spares the lumbar musculature and is restricted to the upper thoracic and neck regions.

CaseNotHPOs:

CaseNotHPOFreeText:

CasePreviousTesting: Serum creatine kinase was 308 iu/l (24–215). There was moderate restrictive lung disease (as determined by formal pulmonary function testing) at age 12 years (FVC 55% of predicted). Electromyography, sural nerve biopsy and cardiac investigations (EKG and echocardiogram) were normal. A quadriceps muscle biopsy taken at age 13 years demonstrated congenital fiber type disproportion. There was type 1 fiber predominance (82%), marked type 1 hypotrophy and type 2 fiber hypertrophy. Muscle MRI scan at age 12 years showed selective fatty infiltration of spinalis muscles in the upper thoracic and cervical regions. Unreported heterozygous variants in RYR1 (p.Asn4200Ser), COL6A3 (p.Ser2829Pro) and TTN (p.Gly4604Glu) were detected, but were all present in a healthy parent. In addition, Sanger sequencing was normal for ACTA1, SEPN1, LMNA, TPM3, TPM2, TNNT1 and MYOZ2.

GenotypingMethod: A heterozygous MYH7 p.Leu1597Arg (c.4790T>G) missense change was found by whole exome sequencing studies, and confirmed by Sanger sequencing. This change was absent in parental DNA samples.

Variant: NM_000257.4:c.4790T>G (MYH7)

ClinVar: not found

CAID: CA389037627

gnomAD: not found

Case1: female, 32 years old

DiseaseAssertion: Myopathy

FamilyInfo: Neither parent presents with MYH7 mutation

CasePresentingHPOs: HP:0002828, HP:0040083, HP:0003722, HP:0012515, HP:0009027, HP:0001371

"Multiple joint contractures, Toe walking, Neck flexor weakness, Hip flexor weakness, Foot dorsiflexor weakness, flexion contractures"

CaseHPOFreeText: Generalized weakness that is most notable in the distal musculature, presented with toe walking age 2 years, required multiple Achilles tendon lengthening surgeries between ages 11–14 years. From age 19 years patient developed progressive weakness and contractures. At age 32 years, patient could walk only short distances and had prominent contractures of the finger flexors, neck flexors, and tendo-Achilles. There was marked weakness of neck flexion, shoulder abduction, hip flexion and ankle dorsiflexion and moderate weakness of wrist/hand flexors and mild weakness of knee flexion/extension. Facial and ocular muscle function was normal.

CaseNotHPOs:

CaseNotHPOFreeText:

CasePreviousTesting: Muscle MRI of the thigh reveals involvement of many muscles including sartorius, quadriceps, and adductors, with relative sparing of biceps femoris. Muscle MRI of the distal lower extremity shows fatty infiltration in the soleus and lateral gastrocnemius with relative sparing of the medial gastrocnemius. Electromyography (EMG) showed myopathic features and serum CK was mildly elevated. Cardiac evaluation (via EKG and echocardiogram) was unremarkable. At age 32 years, based on formal pulmonary function testing, patient exhibited moderate restrictive lung disease (forced vital capacity 63% of predicted). A quadriceps muscle biopsy performed at age 11 years showed non-specific myopathic changes while a gastocnemius biopsy performed at age 32 years showed prominent mini-cores, increased internalized nuclei (~40% of fibers), type I fiber predominance, mildly increased endomysial fibrosis and focal fatty replacement. Sanger sequencing was normal for RYR1 (full exonic sequencing), SEPN1, LMNA, and COL6A1/2/3.

GenotypingMethod: A heterozygous MYH7 p.Leu1597Arg (c.4790T>G) missense change was detected in the patient and not found in either parent.

Variant: NM_000257.4:c.4790T>G (MYH7)

ClinVar: not found

CAID: CA389037627

gnomAD: not found