The American Journal of Human Genetics

Supplemental Data

Recurrent Muscle Weakness with Rhabdomyolysis,

Metabolic Crises, and Cardiac Arrhythmia

due to Bi-allelic TANGO2 Mutations

Seema R. Lalani, Pengfei Liu, Jill A. Rosenfeld, Levi B. Watkin, Theodore Chiang,

Magalie Leduc, Wenmiao Zhu, Yan Ding, Shujuan Pan, Francesco Vetrini, Christina

Miyake, Marwan Shinawi, Tomasz Gambin, Mohammad K. Eldomery, Zeynep Hande

Coban Akdemir, Lisa Emrick, Yael Wilnai, Susan Schelley, Mary Kay Koenig, Nada

Memon, Laura S. Farach, Bradley P. Coe, Mahshid Azamian, Patricia Hernandez, Gladys

Zapata, Shalini N. Jhangiani, Donna M. Muzny, Timothy Lotze, Gary Clark, Angus

Wilfong, Hope Northrup, Adekunle Adesina, Carlos A. Bacino, Fernando Scaglia,

Penelope E. Bonnen, Jane Crosson, Jessica Duis, Gustavo H.B. Maegawa, David

Coman, Anita Inwood, Jim McGill, Eric Boerwinkle, Brett Graham, Art Beaudet,

Christine M. Eng, Neil Hanchard, Fan Xia, Jordan S. Orange, Richard A. Gibbs, James

R. Lupski, and Yaping Yang

Supplemental Data

Supplemental Case Reports

In the fifth family of Hispanic/Latino origin, subject 5 was diagnosed with speech and motor

delay, prolonged QTc interval and seizures, prior to her acute presentation at 7 years of age with

rhabdomyolysis. She had a concurrent mycoplasma infection at that time. Her CPK was reported

to be 60,000 U/L accompanied by myoglobinuria. She had another such episode preceded by

muscle weakness at 13 years of age, with acute rhabdomyolysis and cardiac arrest. She was off

nodalol for about a month prior to her presentation. Her CPK was 33,227 U/L. She was found to

have torsade de pointes from prolonged QTc interval and required defibrillation. Her highest

AST was 953 U/L, ALT was 540 U/L, repeat CPK was 16,790 U/L, with CPK-MB of 291 U/L.

She continued to have brief episodes of ventricular tachycardia (VT) with recurrent pulseless

arrest. Her serum potassium was normal during this time, ranging from 3.8-5.0 mmol/l. She had

a prolonged hospitalization course due to cardiac arrhythmia and subsequently had placement of

dual chamber implantable cardioverter defibrillator (ICD). Prior to discharge from the hospital,

she was ambulating with assistance, and her CPK was mildly elevated to 383 U/L.

Subject 6, a Hispanic male, was born to consanguineous parents who were second cousins once

removed. He was healthy until 1 year of age, albeit with developmental delay. Around one year

of age, he developed emesis and difficulty breathing, and was found to have hypoglycemia of 16

mg/dL, metabolic acidosis with blood gas showing pH of 7.1, bicarbonate of 16 mEq/L (normal

range 22-28 mEq/L), and a base deficit of 24.2 mmol/L. Lactate was elevated to 11.7 mmol/L.

Plasma ammonia level was mildly elevated to 102 μmol/L. CPK was not done during the acute

presentation. An acylcarnitine profile showed elevation of long and very long chain acylcarnitine

species, including C12, C14, C14-OH, C14-1-OH, C16, C16-1, C16-OH, and C16-1-OH. The

magnitude of the elevations was minor with the exception of C14, which was three times the

upper limit of normal. There was massive excretion of lactic acid on urine organic acids, as well

as marked elevations of 3-hydroxy-N-butyric and acetoacetic acids (ketone bodies), as well as

adipic, suberic, sebacic, and 3-hydroxysebacic (dicarboxylic) acids. He was stabilized with

normalization of biochemical studies except for lactate, which remained elevated to 4.1 mmol/L.

His CPK after stabilization was normal at 103 U/L. Chromosomal microarray and Fragile X

studies were performed due to his developmental delay and were normal. Due to failure to thrive,

a gastrostomy was placed to provide adequate nutrition. When evaluated at 16 months of age, he

was unable to sit without assistance and was non-verbal. Physical examination was pertinent for

head circumference at the 6th percentile for age (FOC 45.5 cm) and hypotonia.

Subject 7 was of European ancestry, born to non-consanguineous parents. He was diagnosed

with generalized myoclonic and atonic seizures at 18 months of age. Ketogenic diet was

instituted at 2-½ years of age, and seven days after commencing the diet, he developed lethargy

and hypoglycemia (blood glucose of 12 mg/dL). Dark urine prompted further studies and he was

found to have acute rhabdomyolysis with CPK of 258,000 U/L. Following this episode, he had

neuroregression with mild ataxia, spasticity of lower extremities, and global developmental

delay. Muscle biopsy studies showed normal electron transport chain and mitochondrial DNA

content. Acylcarnitine profile, when he was metabolically stable, showed no abnormalities. Brain

MRI was essentially normal. Echocardiogram and 24-hour holter monitoring were normal. He

had one more similar episode of rhabdomyolysis before 4 years of age. His physical exam at age

9 years demonstrated myopathic facies, with brisk deep tendon reflexes, bilateral clonus and

scissoring gait.

Subjects 8, 9 and 10 from family 8 were born to non-consanguineous parents of European origin.

Subjects 8 (II-1-female) and 9 (II-2-male) were a product of a dichorionic, diamniotic twin

pregnancy. Global developmental delay was noted in the twins by 9 months of age. Seizures

were apparent in the female by 11 months and male by 15 months. Brain MRI in both twins

showed generalized cerebral atrophy with Wallerian degeneration of the cerebral peduncles.

Barium swallow showed oropharyngeal dysphagia. The CPK in subject 9 was always slightly

elevated, but with an intercurrent illness at 15 months, he had rhabdomyolysis with a peak CPK

of 17,900 U/L. Ammonia was mildly elevated to 120 umol/L. The twin female also had

rhabdomyolysis with CPK peaking at 97,500 U/L. The physical examination of both individuals

was pertinent for deceleration of growth parameters, hypertonia, and hyperreflexia with clonus.

The echocardiogram in the male was normal, however hypertrophic cardiomyopathy was noted

in the female at 20 months of age, requiring treatment with frusemide and captopril.

Acylcarnitine profile, mitochondrial studies, including POLG sequencing and respiratory chain

studies were normal. At 22 months of age, the affected male was found unconscious with blood

glucose of 21 mg/dL and lactate of 7.1 mmol/L. He was transferred to a pediatric intensive care

unit but unfortunately died the next day. The female twin passed away soon after her second

birthday due to worsening cardiomyopathy. The sibling of the twins (II-3-female; subject 10) is

currently living at one year of age, but has had seven episodes of severe acidosis usually

triggered by emesis, with pH going as low as 6.9, in association with lactic acidosis (peak lactate

17.1 mmol/L) and hypoglycemia. Ammonia was elevated during these episodes with highest

being 520 umol/L. Her CPK is usually normal and has been as high as 248 U/L. Urine organic

acids showed marked ketoacidosis, lactic acidosis and dicarboxylic aciduria. Plasma

acylcarnitine profile showed a pattern suggestive of VLCAD deficiency: C14:1 of 4.9 umol/L

(normal <0.73 umol/L), C14 of 1.5umol/L (normal <0.34 umol/L) and C10 of 0.6 umol/L

(normal <0.40 umol/L) with normal 3-hydroxybutyrylcarnitine and acetylcarnitine.

In family 9, subjects 11 and 12 were born to Middle Eastern consanguineous parents from Saudi

Arabia. Subject 11 (II-1) was a product of a monozygotic twin pair. The onset of first

neurological symptoms occurred by 2 years of age with recurrent jerky movements of upper and

lower limbs associated with recurrent falls. He was noted to have a progressively unsteady gait

and severe dysarthria with unintelligible speech. By 8 years, he was diagnosed with seizures,

dystonia, and global developmental delay. The brain MRI showed microcephalic appearance of

the brain but no structural abnormality. His TSH was reportedly high and T4 was normal.

During his hospitalization at age 8 years, he presented with generalized progressive weakness

and was found to have acute rhabdomyolysis. The initial evaluation showed elevated plasma

CPK >100,000 U/L and serum myoglobin of 8,366 ng/mL (normal <85 ng/mL). Aldolase was

elevated to 240 U/L, AST was 2,773 U/L and ALT was 1,305 U/L. Plasma acylcarnintine profile

showed elevations of propionyl-carnitine (C3; 1.01 umol/L: normal range <0.92 umol/L) and

decenoyl-carnitine (C10; 0.52 umol/L; normal range <0.40 umol/L) species. Cardiac assessment

showed normal ECG and echocardiogram. The twin monozygotic sibling of subject 11 shared a

similar clinical course and died at the age of 7 during an acute crisis of rhabdomyolysis. He had a

history of seizures with confirmatory atypical EEGs, progressive gait instability, and global

developmental delayed first noted by 2 years of age and reported dystonia versus spastic

diplegia. At 7 years of age, he presented with worsening of generalized weakness, inability to

walk, poor feeding, constant drooling and weight loss of about 3 kg during this time period.

Initial work-up showed a CPK of 33,048 U/L, elevated transaminases, with AST of 1,196 U/L,

an ALT of 423 U/L, and a serum myoglobin of 9,080 ng/mL. The highest CPK was 37,000 U/L

during the acute presentation. He ultimately died in the hospital after a cardiac arrest on the

ventilator.

Subject 12, the younger sibling of the twins in family 9 (II-3), was similarly affected. He was

diagnosed with developmental delay, seizures, hypothyroidism, microcephaly, progressive

spastic diplegia and episodes of poor balance by 4 years of age. He had multiple hospital

admissions for acute episodes of rhabdomyolysis with a peak CPK of 54,258 U/L and maximum

elevated lactate of 8.5 mmol/L. During one these admissions, ECG was characterized by QTc

prolongation. During an acute rhabdomyolysis episode, he developed torsade de pointes

progressing to VT and pulseless electrical activity (PEA) requiring resuscitation. Laboratory

studies at this time showed potassium of 2.4 meq/L (normal range 3.5-5.1 meq/L), magnesium of

2 meq/L (normal range 1.3-2 meq/L), and ionized calcium 1.07 mmol/L (normal range 1.13-1.32

mmol/L). During this admission, the CPK levels reached 38,975 U/L, and serum myoglobin was

elevated to 5,499 ng/mL. Given the clinical improvement, the uncertainty of the etiology and

potential risk of recurrent VT and PEA, an ICD was placed. He later developed involuntary

choreiform movements of the upper extremities. The brain MRI demonstrated subtle

abnormalities in the right lentiform nucleus. A muscle biopsy was performed and quantitative

PCR assay showed no evidence of mitochondrial DNA depletion. Respiratory mitochondrial

complexes enzymatic activity was within normal range. The biopsy revealed mild acute

neurogenic atrophy with no ragged red fibers or COX negative fibers. During the diagnosis

process, a mitochondrial disorder was suspected and vitamins B1, B6, C, E, riboflavin,

levocarnitine and co-enzyme Q-10 were introduced. Interestingly, since starting on these

medications no further episodes of acute rhabdomyolysis and metabolic decompensation were

noted.

Figure S1: Electrocardiograms and ECG changes seen in subjects with TANGO2

mutations. A1-3 demonstrates evolving ECG changes in subject 4. A1 demonstrates marked

QTc prolongation (579msec) with ST elevation in the anterior precordial leads (marked with the

red arrow) consistent with a Brugada Type I pattern. A2 is an ECG taken 41 hours later. The ST

elevation has resolved, however the QTc remains prolonged (500msec). An ECG taken 2

months later is normal. Panel B1-3 represents ECGs from subject 5. B1 demonstrates markedly

prolonged QTc (501msec) with nonspecific ST changes and anterior ST changes similar to A1

although not diagnostic for a Brugada Type I pattern. In B2, taken 7 days later, there is an

undetermined rhythm and may represent a sinus, atrial, or junctional tachycardia. In B3, taken 5

days later, the ECG has relatively normalized. There is nonspecific ST segment depression. The

ST elevation seen previously in the anterior precordial leads is less pronounced. C1-2 represents

ECGs taken from subject 8. The initial ECG (C1) demonstrates QTc prolongation (QTc

490msec, marked by red arrow). C2 is taken few days later and demonstrates low voltages QRS

with nonspecific ST changes. D1-2. The baseline ECG (D1) in subject 9 does not demonstrate

QTc prolongation. Multiple subsequent ECGs demonstrate frequent isolated premature

ventricular contractions (marked by red arrow in D2).

  

Chr22:20028913 GCAAACTCTGCCTCCCGGGTTCACACCATTGTCCTGCCTCAGCCTCCCGAGTAGCTGGGACTACAGGCGCCCGCCACCACACCTGGCTA Exon3-9del GCAAGCTCCGCCTCCCGGGTTCACGCCATTCTCCTGCCTCAGCCTCCCGAGTAGCTGGGACTACAGGCGCCCCCTACCACGCCCGGCTA Chr22:20062731 ACAGAGTGAGACTCCGTCTCAAAAATAAAAAGTAAAATAATAATAATAATAATAAAAGGTAAACAGAAATCTTCATAATCTCAAATACT Chr22:20029002 ATTTTTT--GTATTTTTAGTAGAGACGGGGTTTTACCGTGTTAGCCAGGATGGTCTCGATCTCTTGACCTCGTGATCCTCCCACCTTGG Exon3-9del ATTTTTTTTGTATTTTTAGTAGAGACGGGGTTTCACCGTGTTAGCCAGGATGGTCTCGATCTCCTGACCTCGTGATCCGCCCGCCTCGG Chr22:20062820 GTAAGAAAACTTTGTCATTTCAACAGAGAAGATCAAGTTAAAGTTCTGCATCATAGCACTACTAATAAAGCTAATTTTAACAAAACCTT Chr22:20029089 CCTCTCAAAGTGCTGGGATTACAGGCGTGAGCCACCGGGCCCGGCCTAATTTTTGTATTTTTAATAGAGATGGGGTTTCACCATCTTGG Exon3-9del CCTCCCAAAGTGCTGGGATTACAGGCGTGAGCCACCGCGCCCGGCCAGATTTCTTTTCTATAGATGTTTTACAACTTAAAAAAAATATC Chr22:20062909 ATAAATGAATCCATCCAATCTCATGCAAGATAATATTTCTTTTCCAAGATTTCTTTTCTATAGATCTTTTACAACTTAAAAAAAATATC Chr22:20029178 CCAGGCTGGTCTTGAACTCCTGACCTCATGATCCACCCACCTCGGCCTCGCAAAATGCTGGGATTACAGGCATGAGCCACCGTACCCAG Exon3-9del TGGCCGGGCACCGTGGCTCATGCCTGTAATCCCAGCACTTTGGGAGGCCGAGGCGGGTGGATCATGAGGGCAGGAGATTGAGACCAGCC Chr22:20062998 TGGCCGGGCACGGTGGCTCATGCCTGTAATCCCAGCACTTTGGGAGGCCGAGGCGGGTGGATCATGAGGTGAGGAGATCGAGACCAGCC  

rs573015985  A: 99.980% (5007 / 5008); G: 0.020% (1 / 5008) 

rs544842733            No data available 

rs193263084  No data available 

rs530937322  No data available 

rs174881   C: 50.000% (4 / 8); G: 50.000% (4 / 8) 

rs73150865  C: 66.667% (4 / 6); G: 33.333% (2 / 6) 

rs695492   G: 50.000% (3 / 6); T: 50.000% (3 / 6) 

rs695519   C: 50.000% (2 / 4); G: 50.000% (2 / 4) 

rs174883   C: 25.000% (1 / 4); T: 75.000% (3 / 4) 

Figure S2: Tag SNPs around the breakpoint for the TANGO2 exons 3-9 deletion in families 2, 7

and 8. The breakpoint junction sequence is aligned with reference sequences to illustrate the transition

from the proximal (red) to the distal (blue) breakpoints. Nucleotides that do not match perfectly to

reference sequences are highlighted in yellow or green. Those in yellow are variants present in

dbSNP142. Their rs numbers and allele frequencies, if available, are listed in the order they appear. The

12 nucleotides in green are absent in dbSNP142, potentially reflecting novel private mutations.

Figure S3: TANGO2 p.Gly154Arg haplotypes. The figure shows 23 SNPs (columns) with

minor allele frequency (MAF) > 1% (dbSNP142) in the ~1.4-Mb region surrounding TANGO2

on the cSNP array. The rs numbers and associated genomic position (hg19) are given,

respectively, below and above each SNP position. Each row represents a unique subject. At each

SNP position dark blue shaded squares represent the homozygous genotype of one allele and

light blue the homozygous genotype of the alternate allele; heterozygous genotypes are

represented in mid-blue. Genotypes for subjects 1, 3, and 4 have the same homozygous genotype

at each position across the ~1.4 Mb region interrogated, suggesting a shared ancestry; subject 6

(consanguineous) shows a similar pattern of homozygosity across the region, but with different

genotype states at most SNP positions. Subjects with exons 3-9 deletion share a smaller region

of homozygosity (~825 kb).

*SNPs with MAF <5% but >1%

Figure S4: Multiple protein sequence alignment using ClustalW. Multiple protein sequence

alignment using ClustalW shows evolutionary conservation of Gly154 residues in TANGO2

orthologs. The Gly154 is conserved from D. melanogaster to Human, but not in C. elegans. The

change was predicted to be probably damaging and damaging by PolyPhen 2 and SIFT programs

respectively.

Figure S5: Tertiary structures of the wild-type (WT) and the p.Gly154Arg mutant

TANGO2 proteins. Images are predicted by Phyre2 web server

(http://www.sbg.bio.ic.ac.uk/phyre2) based on sequence homology with proteins with known 3D

structures. Arrows show the Gly or Arg with side chains in spheres at position 154. Arrowheads

show the structural differences between the WT and the p.Gly154Arg mutant.

Table S1: Clinical features of subjects with bi-allelic TANGO2 mutations

Family 1

Subject 1

II-1

Family 2

Subject 2

II-1

Family 3

Subject 3

II-1

Family 4

Subject 4

II-1

Family 5

Subject 5

II-1

Family 6

Subject 6

II-1

Family 7

Subject 7

III-2

Family 8

Subject 8

II-1

Family 8

Subject 9

II-2

Family 8

Subject 10

II-3

Family 9

Subject 11

II-2a

Family 9

Subject 12

II-3

Age at first

presentation

4 years

6 months 5 months 8 years 7 years 1 year 18 months 9 months 1 year 3.5 months 2 years 4 years

Current age 6 years 6 years 27 years 14 years 17 years 3 years 9 years Deceased

(2 years)

Deceased

(22 months)

11 months 11 years 8 years

Gender Female Female Female Male Female Male Male Female

Dizygotic twin

Male

Dizygotic twin

Female Male

Monozygotic

twin

Male

Ethnicity Hispanic Hispanic/

European

Hispanic Hispanic Hispanic Hispanic European European European European Arab Arab

Parental

relationship

Non-

consanguineous

Non-

consanguineous

Non-

consanguineous

Non-

consanguineous

Non-

consanguineous

Consanguineous Non-

consanguineous

Non-

consanguineous

Non-

consanguineous

Non-

consanguineous

Consanguineous Consanguineous

Nucleotide

change

c.460G>A c.460G>A

c.460G>A c.460G>A c.460G>A c.605+1G>A - - - - - -

Amino acid

change

p.Gly154Arg p.Gly154Arg p.Gly154Arg p.Gly154Arg p.Gly154Arg

Exonic deletion - Exons 3-9 del - - - - Exons 3-9 del Exons 3-9 del Exons 3-9 del Exons 3-9 del Exons 4-6 del

Exons 4-6 del

Mutation Homozygous Compound

heterozygous

Homozygous Homozygous Homozygous Homozygous Homozygous Homozygous Homozygous Homozygous Homozygous Homozygous

Highest CPK

205,000 U/L 287,230 U/L 22,000 U/L 16,674 U/L 60,000 U/L 103 U/L 258,000 u/L 97,500 U/L 17,900 U/L 248 U/L >100,000 U/L 54,258 U/L

Rhabdomyolysis

Yes Yes Yes Yes Yes No Yes Yes Yes No Yes Yes

Glucose

Hypoglycemia Hypoglycemia Hypoglycemia Normoglycemia Hypoglycemia Hypoglycemia Hypoglycemia Hypoglycemia Hypoglycemia Hypoglycemia Normoglycemia Normoglycemia

Ammonia

↑ ↑ Normal ↑ ND ↑ ↑ Normal ↑ ↑ ↑ ↑

Lactate ND ↑ ↑ Normal ↑ ↑ ↑ ↑ ↑ ↑ ↑ ↑

Brain MRI Mild diffuse

atrophy of left

cerebral

hemisphere,

mild optic

chiasm

hypoplasia

Asymmetric

and prominent

lateral

ventricles

No structural

abnormalities Mild cerebellar

volume loss

Prominent

lateral

ventricles,

likely due to

decrease in the

amount of

cerebral white

ND No structural

abnormalities

Generalized

cerebral

atrophy with

Wallerian

degeneration of

the cerebral

peduncles

Wallerian

degeneration of

the cerebral

peduncles

ND No structural

abnormalities

Subtle

abnormalities in

the right

lentiform

nucleus

matter

Seizures Yes No Yes Yes Yes No Yes Yes Yes No Yes Yes

Intellectual

disability

Yes Yes

Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes

Echocardiogram Normal Normal Normal Normal Normal ND Normal Hypertrophic

cardiomyopathy

Normal Normal Normal Normal

ECG/

Arrhythmia

Normal Prolonged QTc

interval,

ventricular

tachycardia

Ventricular

tachycardia

requiring ICD

placement

Prolonged QTc

interval,

Brugada pattern

Prolonged QTc

interval,

torsade de

pointes,

requiring ICD

placement

ND Normal Prolonged QTc

interval

Bradycardia

and premature

ventricular

contractions

and junctional

rhythm.

Prolonged QTc

interval

Normal Normal Prolonged QTc

interval, torsade

de pointes

progressing to

ventricular

tachycardia,

requiring ICD

placement

Other notable

problems

Acquired

microcephaly

Transient

hypothyroidism

considered to

be related to

amiodarone

Bilateral

hearing loss,

head

circumference

at 5%

Hypothyroidism Macrocephaly Failure to thrive Failure to

thrive

Failure to

thrive

responding to

nasogastric

feedings

Hypothyroidism Hypothyroidism

ND=Not determined

ICD= automatic implantable cardioverter-defibrillator

aMonozygotic male twin of Subject 11 had a very similar presentation, but passed away at 7 years of age before molecular confirmation could be obtained