Supplementary Table 1: Clinical Evaluation of Patients. the Annotation of The

Supplementary Table 1: Clinical evaluation of patients. The annotation of the

patients is according to Fig. 1A. Abbreviations: LVESD: left ventricular end systolic

diameter, LVEDD: left ventricular end diastolic diameter (adult norm: 35-54mm), EF:

ejection fraction. BSA: body surface area, NSR: normal sinus rhythm, LVH: left

ventricular hypertrophy, SVT: supraventricular tachycardia. DCM patients are marked

in red.

LVEDD LVESD Posterior BSA patient sex age IVSEPTUM EF% ECG (mm) (mm) wall M2

51 NSR I-2 Male 63Y 30 11 10 65% 2.27 No LVH

45 NSR I-3 Female 56Y 26 11 10 60% 1.94 No LVH

50 NSR II-1 Male 36Y 33 10 9 60% 2.18 No LVH Female 49 29 NSR II-2 31Y 7 6 60% 1.88 No LVH 49 NSR II-3 Male 34Y 28 11 10 60% 2.29 No LVH NSR II-4 48 Female 33Y 27 9 8 62% 1.87

No LVH 66 60 SVT, severe III-1 Female 9Y Z-score: 7 7 28% 1.49 LVH +6.58 28 16 NSR III-2 Male 22M Z-score 6 6 67% 0.61 No LVH -1.4 NSR III-3 Female 6Y 33 18 6 5 63% 1.02 No LVH 35 Z-score 21 NSR III-4 Female 4Y 6 6 60% 0.92 +0.77 No LVH

60 SVT, 57 III-5 Male 12Y Z-score 7 7 5% 1.47 Severe

+5 LVH 35 Z-score NSR III-6 Male 7Y 16 5 5 68% 1.04 +0.78 No LVH

NSR III-7 Male 4M 24 12 4 4 70% 0.28 No LVH

Supplementary Table 2: Number of variants in the exome sequence of patient III-5 with

allele frequency of less than 1% in the public databases: gnomad browser, 1000 Genomes,

ExAC and EVS and the reason for their negation as the causative mutation.

Number of The cause of negation variants that were negated

Common variants according to our internal laboratory 17 Exome database of the Bedouin population

Common variants according to a database of healthy Saudi 18 individuals with LOF in varies genes (Alsalem et al. 2013)

Low prediction for damage (Omicia score) 3

Weak splice site prediction impact according to the Berkeley 1 Drosophila Genome Project prediction program

An homozygote individual/s in the genomAD browser data 5

Segregation (second patient not presenting variation in 9 homozygosity)

Supplementary Table 3: List of variants that were negated by lack of segregation in patient III-1. Positions are according to GRCh37/hg19. Zygosity in Variants negated by segregation Patient III-1

1 Chromosome 1:207647230 G to A, c.2240G>A p.Gly747Glu Normal Complement C3d Receptor 2 protein (CR2) gene homozygote

2 Chromosome 10:27326228 G to C, c.2584C>G p.Gln862Glu Normal Ankyrin Repeat Domain 26 protein (ANKRD26) gene homozygote

3 Chromosome 10: 27337797 G to C, c.1747C>G p.Gln583Glu Normal Ankyrin Repeat Domain 26 protein (ANKRD26) gene homozygote

4 Chromosome 1:197887095 G to A, c.142G>A p.Ala48Thr Normal LIM Homeobox 9 protein (LHX9) gene homozygote

5 Chromosome 21: 46935943 C to A, c.1405G>T p.Ala469Ser Heterozygote Solute Carrier Family 19 Member 1 (SLC19A1) gene

6 Chromosome 16: 81301741 G to A, c.843+5G>A Normal homozygote beta-carotene oxygenase 1 (BCMO1) gene

7 Chromosome 10: 43127813 G to T, c.84C>A p.His28Gln Normal Zinc Finger Protein 33B (ZNF33B) gene homozygote

8 Chromosome 10: 43127814 G to T, c.83A>T p.His28Leu Normal Zinc Finger Protein 33B (ZNF33B) gene homozygote

9 Chromosome 10: 62038628 T to C, c.318A>G p.Lys106Lys Normal Ankyrin 3 (ANK3) gene homozygote

Supplementary Table 4: Full list of the 54 homozygous variants that were negated and the cause of negation

Negated by common in internal laboratory Exome database of the Bedouin population

Position Omicia No Gene Change Effect dbSNP Score

C → G chr1:148023129 1 NBPF14 c.380G>C missense 0.446 rs202128472 p.Glu127Asp

G → C missense chr1:152189055 2 HRNR c.5050C>G splice site 0.049 rs4845749 p.Arg1684Gly impact

T → G chr7:45123906 0.043 3 NACAD c.1873A>C missense rs61740887 p.Ile625Leu

chr7:148106477 C → G 4 CNTNAP2 splice region 0.243 rs77025884 c.3716-6C>G

CTCA → C chr9:95237024 5 ASPN c.153_155delTGA inframe deletion 0.5 rs878929025 p.Asp51del

A → C chr10:48029324 6 ASAH2C c.562T>G missense 0.087 rs993869 p.Ser188Ala

ACAGCAGCAGCAGC AGCAGCAG → A

7 ATN1 chr12:7045891 c.1488_1508delGCAGC inframe deletion 0.5 AGC...

p.Gln496_Gln502del

A → AGAGGAG chr14:24769849 inframe 8 NOP9 c.504_509dupGGAGGA 0.5 rs113258190 insertion p.Glu168_Glu169dup C → CCTGCTGCTGCTG chr14:92537354 inframe 9 ATXN3 c.904_915dupCAGCAG 0.5 insertion rs763541221 CAGCAG

p.Gln302_Gln305dup

A → C

10 GOLGA6L6 chr15:20740040 c.1710T>G missense 0.07

p.Asp570Glu

C → G chr15:23685206 11 GOLGA6L2 c.2416G>C missense 0.258 rs112738749 p.Ala806Pro

A → C chr16:88599697 12 ZFPM1 c.1331A>C missense 0.044 rs368520732 p.Glu444Ala

G → C chr16:88599698 13 ZFPM1 c.1332G>C missense 0.045 rs201915453 p.Glu444Asp

CCTCTGG → C

chr16:88599699 c.1335_1340delTCTGG 14 ZFPM1 inframe deletion 0.5 rs149145771 C p.Leu446_Ala447del

C → T chr18:25727748 15 CDH2 c.61G>A missense 0.781 rs17495042 p.Ala21Thr

G → A chr18:29116284 16 DSG2 c.1543G>A missense 0.899 rs2230235 p.Val515Ile

C → G chr18:46284585 17 CTIF c.880C>G missense 0.317 rs145237824 p.Leu294Val

Negated by common variants according to a database of healthy Saudi individuals with LOF in varies genes (Alsalem et al. 2013)

Position Omicia No Gene Change Effect dbSNP Score

A → C chr1:198723439 1 PTPRC c.3551A>C missense 0.65 rs762923302 p.Asn1184Thr

C → A chr1:212970533 2 TATDN3 c.253C>A missense 0.275 rs148528899 p.Leu85Ile

T → A chr1:228526578 3 OBSCN c.19980T>A missense 0.245 rs144372515 p.Ser6660Arg

C → T chr3:75786415 4 ZNF717 c.2359G>A missense 0.649 rs77511709 p.Glu787Lys

C → T chr3:75786453 5 ZNF717 c.2321G>A missense 0.074 rs77961859 p.Ser774Asn

A → C chr3:75788076 6 ZNF717 c.698T>G missense 0.442 rs62250111 p.Val233Gly

A → G chr3:75788085 7 ZNF717 c.689T>C missense 0.144 rs201605431 p.Val230Ala

C → T chr3:75788105 8 ZNF717 c.669G>A missense 0.073 rs796745611 p.Met223Ile

G → A missense chr3:75788109 9 ZNF717 c.665C>T splice site 0.076 rs796849627 p.Ala222Val impact C → T chr3:75788130 10 ZNF717 c.644G>A missense 0.088 rs113708852 p.Gly215Glu

C → T ZNF717 chr3:75788137 11 c.637G>A missense 0.204 rs199883677 p.Glu213Lys

C → A chr7:144101728 12 NOBOX c.131G>T missense 0.052 rs115206969 p.Arg44Leu

chr7:149476781 G → C 13 SSPO splice region 0.249 rs745841041 n.1224+7G>C

G → C chr7:155301717 14 CNPY1 c.16C>G missense 0.927 rs73163379 p.Leu6Val

C → T chr10:26856281 15 APBB1IP c.1865C>T missense 0.156 rs200114349 p.Ala622Val

C → T chr16:74678537 16 RFWD3 c.889G>A missense 0.832 rs138454127 p.Ala297Thr

G → T chr16:82033586 17 SDR42E1 c.312C>A missense 0.044 rs769262424 p.Asp104Glu

G → A chr19:48305586 18 TPRX1 c.682C>T missense 0.1 rs145255760 p.Pro228Ser

Negated by low prediction for damage (Omicia score)

Position Omicia No Gene Change Effect dbSNP Score

chr14:74823778 G → A 1 VRTN missense 0.061 rs140827396 c.292G>A p.Ala98Thr

A → G chr11:56237609 2 OR5M3 c.365T>C missense 0.118 rs200070203 p.Met122Thr

C → A chr7:150747236 3 ASIC3 c.578C>A missense 0.156 rs141910870 p.Ala193Asp

Negated by weak splice site prediction impact of Berkeley Drosophila Genome Project prediction program (http://www.fruitfly.org/seq_tools/splice.html)

Position Omicia No Gene Change Effect dbSNP Score

chr1:232626815 T → G 1 SIPA1L2 splice region 0.245 rs776937773 c.1618-7A>C

Negated by an homozygote individual/s in the genomAD browser data

Position Omicia No Gene Change Effect dbSNP Score

chr7:143096736 G → A 1 EPHA1 splice region 0.243 rs149923216 c.835+8C>T

G → A NO chr7:144094553 2 c.1856C>T missense 0.19 NOBOX rs146227301 p.Pro619Leu

chr7:144101781 G → A 3 NOBOX splice region 0.243 rs189548165 c.86-8C>T

T → C chr16:2070066 4 NPW c.164T>C missense 0.715 rs573754213 p.Leu55Pro

G → A chr18:48256003 5 MAPK4 c.1543G>A missense 0.646 rs573296530 p.Glu515Lys

Negated by segregation (second patient not presenting variation in homozygosity)

Position Omicia No Gene Change Effect dbSNP Score

C → A missense chr21:46935943 1 SLC19A1 c.1405G>T splice site 0.68 rs560827689 p.Ala469Ser impact

splice region G → A 2 BCMO1 chr16:81301741 splice site 0.564 c.843+5G>A impact

T → C

3 ANK3 chr10:62038628 c.318A>G splice region 0.808

p.Lys106Lys

T → A

4 ZNF33B chr10:43127814 c.83A>T missense 0.314

p.His28Leu

G → T

5 ZNF33B chr10:43127813 c.84C>A missense 0.17

p.His28Gln

G → C chr10:27326228 6 ANKRD26 c.2584C>G missense 0.686 rs74128547 p.Gln862Glu

G → C chr10:27337797 7 ANKRD26 c.1747C>G missense 0.193 rs56151272 p.Gln583Glu

G → A

8 CR2 chr1:207647230 c.2240G>A missense 0.855

p.Gly747Glu

G → A chr1:197887095 9 LHX9 c.142G>A missense 0.605 rs113693840 p.Ala48Thr

Supplementary Figure 1: Western blot analyses results for CAP1. Fibroblast cell lysates of patient III-1 and 2 controls (C1, C2) , the bands observed with each of the antibodies are marked: mouse anti-CAP1 antibody (SC-376191), mouse anti GAPDH (Millipore MAB374). One out of two experiments with different lysates showing identical results.

kDa

III-1 C1 C2 72 αCAP1 55

αGAPDH 36

Supplementary Figure 2: Western blot analyses results for actin . Fibroblast cell lysates of patient III-1 and 2 controls (C1, C2), the bands observed with each of the antibodies are marked: mouse anti- actin  antibody (Sigma A2228), mouse anti GAPDH (Millipore MAB374).