Case III.4: Female, age 30

DiseaseAssertion: Distal myopathy

FamilyInfo: Figure 1, similar distal muscle weakness in four relatives. Patients I.2 and II.2 experienced foot drop while walking. Patient III.2 muscle biopsy findings suggestive of core myopathy suggested a disorder similar to his youngest sister. Patient IV.1 displayed a less progressive muscular phenotype than her older relatives and tested negative for the mutation in RYR1

CasePresentingHPOs: HP:0001761, HP:0008994, HP:0002650

"Pes cavus, Proximal muscle weakness in lower limbs, Scoliosis"

CaseHPOFreeText: stepping gait

CasePreviousTesting: muscle biopsy showed fiber size variability, increased internal nuclei and histochemical evidence of eccentric core-like lesions, Analysis of RYR1 revealed a heterozygous c.880G > A:p.(Glu294Lys) mutation

GenotypingMethod: Amplicon-based Sanger sequencing, MotorPlex used to analyze a large set of genes that cause known forms of non-syndromic muscle disorders

MultipleGeneVariants:

(1) MHY7Variant: Novel

Variant: NM_000257.4:c.4303T>C

ClinVar: not found

CAID: CA389040164

gnomAD: not found

(2) RYR1Variant:

Variant: NM_000540.2:c.880G>A

ClinVar: 590621

CAID: CA072725

gnomAD: https://gnomad.broadinstitute.org/variant/19-38939074-G-A?dataset=gnomad_r2_1

Total allele frequency: 0.00006159 European (non-Finnish)

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

Case1: 43 year old Caucasian female

DiseaseAssertion: LVHT, mild distal myopathy

FamilyInfo: LVHT was absent in all other family members who had undergone echocardiography, same MYH7 mutation detected in mother, who manifested with a mild distal myopathy

CasePresentingHPOs: HP:0001962, HP:0001279, HP:0004756, HP:0004308, HP:0012391

"Palpitations, Syncope, Ventricular tachycardia, Ventricular arrhythmia, Hyporeflexia of upper limbs"

CaseHPOFreeText: ectopic atrial tachycardia, mild weakness for foot extension on the right side, reduced Achilles tendon reflexes

CaseNotHPOs: n/a

CaseNotHPOFreeText: n/a

CasePreviousTesting: n/a

GenotypingMethod: n/a

Variant: NM_000257.4:c.5566G>A

ClinVar: 190403

CAID: CA347253

gnomAD: https://gnomad.broadinstitute.org/variant/14-23883305-C-T

0.000008795 European (non-Finnish)

DiseaseAssertion: Cardiomyopathy

VariantPreviousTesting: ACTC1, ACTN2, CSRP3, LAMP2, MYBPC3, MYH7, NEXN, PLN, TNNC1, TNNI3, TNNT2, TPM1, ABCC9, CTF1, DES, EMD, LDB3, LMNA, MYH6, RBM20, SGCD, TAZ, TCAP, TTN, VCL, CAV3, GLA, MYL2, MYL3, MYOZ2, PRKAG2, TTR, DSC2, DSG2, DSP, JUP, PKP2, RYR2, TMEM43, CASQ2 and RYR2 were all tested in the PanCM panel.

VariantGenotypingMethod: Next-generation sequencing panels were used to sequence and read the genetic information of the 305 PanCM probands for variants within exons and in +/- 10 nucleotides within the flanking introns of the genes provided above. These variants were then interpreted and filtered for pathogenicity.

VariantAddInfo: Seen in two PanCM probands

Variant: NM_000257.4(MYH7):c.4498C>T (p.Arg1500Trp)

ClinVar: 164284 https://www.ncbi.nlm.nih.gov/clinvar/variation/164284/

gnomAD: Not in gnomAD

DiseaseAssertion: Cardiomyopathy

VariantPreviousTesting: ACTC1, ACTN2, CSRP3, LAMP2, MYBPC3, MYH7, NEXN, PLN, TNNC1, TNNI3, TNNT2, TPM1, ABCC9, CTF1, DES, EMD, LDB3, LMNA, MYH6, RBM20, SGCD, TAZ, TCAP, TTN, VCL, CAV3, GLA, MYL2, MYL3, MYOZ2, PRKAG2, TTR, DSC2, DSG2, DSP, JUP, PKP2, RYR2, TMEM43, CASQ2 and RYR2 were all tested in the PanCM panel.

VariantGenotypingMethod: Next-generation sequencing panels were used to sequence and read the genetic information of the 305 PanCM probands for variants within exons and in +/- 10 nucleotides within the flanking introns of the genes provided above. These variants were then interpreted and filtered for pathogenicity.

VariantAddInfo: Seen in one PanCM proband

Variant: NM_000257.4(MYH7):c.2770G>A (p.Glu924Lys)

ClinVar: 14092 https://www.ncbi.nlm.nih.gov/clinvar/variation/14092/

gnomAD: Not in gnomAD

CaseII.1: 67 year old female, proband

DiseaseAssertion: progressive asymmetric distal limb weakness - Welander distal myopathy

FamilyInfo: 66-year-old sister has a mild distal myopathy, supraventricular tachycardia and hypertrophic cardiomyopathy. Both sisters carry the only known pathogenic TIA1 mutation and a heterozygous MYH7 variant (c.5459G > A; p.Arg1820Gln). Another sibling with isolated distal myopathy carries only the TIA1 mutation.

CasePresentingHPOs: HP:0002460, HP:0003805

"distal limb weakness, rimmed vacuoles"

CaseHPOFreeText: congophilic inclusions

CaseNotHPOFreeText: cardiac involvement

CasePreviousTesting: Electromyography - showed myopathic changes in distal upper and lower limb muscles with fibrillation potentials and rare myotonic discharges. Neurological examination - asymmetric weakness limited to distal muscles.

ANO5, BAG3, CAV3, CRYAB, DES, DNAJB6, DYSF, FHL1, FLNC, GNE, LDB3, MATR3, MYH7, MYOT, TCAP, TIA1, TTN and VCP were tested, all coding regions plus 20 bp flanking non-coding regions were analyzed through a combination of targeted next generation sequencing and Sanger sequencing

MultipleGeneVariants:

(1) MYH7Variant: NM_000257.4:c.5459G>A

ClinVar: 419278

CAID: CA046848

gnomAD:https://gnomad.broadinstitute.org/variant/14-23884304-C-T

Allele Frequency: East Asian 0.00005437

(2) TIA1Variant: NM_022173.4:c.1150G>A

ClinVar: 41480

CAID: CA1697383

gnomAD: https://gnomad.broadinstitute.org/variant/2-70439862-C-T?dataset=gnomad_r2_1

Total Allele Frequency: Other 0.0001629

GenotypingMethod: Targeted next generation sequencing and Sanger sequencing

DiseaseAssertion: cardiomyopathy

Variant: NM_000257.4:c.2543A>G

ClinVar: 177758

CAID: CA012584