Patient acceptance of genetic testing for familial hypercholesterolemia in the CASCADE FH Registry

Journal Pre-proof Patient Acceptance of Genetic Testing for Familial Hypercholesterolemia in the CASCADE FH Registry Samuel S. Gidding, MD, Amanda Sheldon, Cynthia L. Neben, PhD, Hannah E. Williams, MPH, Sherman Law, Alicia Y. Zhou, PhD, Katherine Wilemon, Catherine D. Ahmed, Iris Kindt, MD, MPH PII:

S1933-2874(20)30016-7

DOI:

https://doi.org/10.1016/j.jacl.2020.02.001

Reference:

JACL 1551

To appear in:

Journal of Clinical Lipidology

Received Date: 26 November 2019 Revised Date:

21 January 2020

Accepted Date: 3 February 2020

Please cite this article as: Gidding SS, Sheldon A, Neben CL, Williams HE, Law S, Zhou AY, Wilemon K, Ahmed CD, Kindt I, Patient Acceptance of Genetic Testing for Familial Hypercholesterolemia in the CASCADE FH Registry, Journal of Clinical Lipidology (2020), doi: https://doi.org/10.1016/ j.jacl.2020.02.001. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2020 Published by Elsevier Inc. on behalf of National Lipid Association.

Patient Acceptance of Genetic Testing for Familial Hypercholesterolemia in the CASCADE FH Registry Samuel S. Gidding MDa, Amanda Sheldona, Cynthia L. Neben PhDb, Hannah E. Williams MPHb, Sherman Law2b Alicia Y. Zhou PhDb, Katherine Wilemona, Catherine D. Ahmeda, Iris Kindt MD, MPHa a

FH Foundation, 959 E Walnut Street, Suite 220, Pasadena CA 91106, USA

b

Color Genomics, 831 Mitten Road, Suite 100, Burlingame CA, 94010, USA

Running Title: FH Genetic Testing

Corresponding Author: Samuel S. Gidding MD1 [email protected] +1 626-583-4674

Source of funding: This study was funded by a grant from the COLOR Foundation to the FH Foundation and additional FH Foundation funds. 1

1631 Hale Hollow Road, Bridgewater Corners VT 05035, USA

Co-Author emails: AS:[email protected]; CLN: [email protected]; HEW: [email protected]; SL:[email protected]; AYZ:[email protected]; KW:[email protected]; CDA:[email protected]; IK: irishommeskindt @hotmail.nz

Abstract Background: Barriers to genetic testing and subsequent family cascade screening for familial hypercholesterolemia (FH) include cost, patient and provider awareness, privacy and discrimination concerns, need for a physician order, underutilization of genetic counsellors, and family concerns about the implications of genetic testing for care, Objectives: To determine the uptake of genetic testing with cost and privacy removed. Methods:, The FH Foundation offered free genetic testing and counseling to patients in the patient portal of the CASCADE FH Registry, who had not previously undergone genetic testing for three genes associated with FH (LDLR, APOB, and PCSK9). The free testing offer was extended to first-degree relatives of participants who had a positive genetic test result for cascade screening. Results: Of 435 eligible patients, 147 opted in to participate, 122 consented, and 110 (68.2% female, median age 52 years) received genetic testing. Of participants, 64 had a positive genetic test result for a pathogenic variant in LDLR (59) or APOB (5); 11 had a variant of uncertain significance. Only three first-degrees relatives underwent genetic testing. Conclusions: While there was substantial interest in genetic testing, uptake of family cascade screening was poor. Innovative approaches to increase family cascade screening should be explored.

Key Words: familial hypercholesterolemia, genetic testing, cascade screening, patient-centered research, cholesterol

2

Introduction Familial hypercholesterolemia (FH) is the most common genetic condition associated with premature atherosclerotic heart disease.1 Across Europe, genetic testing and subsequent family cascade screening for FH has been adopted in many countries.2 In the United States, and similar to Lynch syndrome and hereditary breast and ovarian cancer syndrome, FH is recognized as a Tier 1 genomics application by the Centers for Disease Control and Prevention, signifying there is value for prevention by performing family-based genetic screening and subsequent management of those affected by the condition.1 Cost-effectiveness studies have demonstrated the value of family cascade screening for FH.3,4,5 Despite this, uptake of genetic testing for FH in the United States remains low: only about 8% of patients in the FH Foundation CASCADE FH Registry have been diagnosed by genetic testing, compared to well over 90% in other FH registries around the world.6 There is limited data on the uptake of genetic testing for FH in the United States. Barriers to genetic testing and family cascade screening exist in the United States and include cost, need for a physician order, patient and provider awareness, a shortage of genetic counsellors to provide support, privacy and discrimination concerns, and patient and family concerns about the implications of genetic testing on current and future care.7 The purpose of this study was to determine, with the majority of these barriers removed, the uptake of genetic testing by patients enrolled in the CASCADE FH Registry Patient Portal and their at-risk first-degree relatives. Specifically, free genetic testing and counseling was offered to enrolled FH patients, who had not previously received genetic testing. Uptake of patient genetic testing and yield from family cascade screening were study outcomes.

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Patients and Methods Regulatory approval for this study was obtained from the Western IRB. Participants in the CASCADE FH Registry Patient Portal who had not previously had genetic testing documented were sent an online invitation via the Patient Portal to receive free genetic testing for three genes associated with FH (APOB, LDLR, and PCSK9). Everyone who agreed to participate in the lottery received an informed consent form. Since the number of signed consents was equal to the projected sample size, the lottery was not conducted. Upon consent, a genetic testing kit to provide a saliva sample was sent. Children were not enrolled in the patient portal but were eligible for family screening. Genetic testing was physician ordered and performed at the Color Genomics laboratory under CLIA and CAP compliance.8,9 Analysis, variant calling, and reporting focused on the complete coding sequence and adjacent intronic sequence of the primary transcript(s) for all three genes, with the following exception: for the LDLR promoter region, the detection of deletions, duplications, and complex structural rearrangements may have been limited. Complementary genetic testing was available to all participants, regardless of test outcome, throughout the course of the study. All positive results were disclosed to participants by a board-certified genetic counselor during a genetic counseling session. Participants who tested positive were also given the opportunity to obtain free genetic testing and counseling for their first-degree relatives. Demographics and health history were reported by participants through an online, collaborative health history tool; information not provided was noted as such. Individuals who reported more than one ethnicity were counted as multiple ethnicities, with the following exception: individuals who reported Ashkenazi Jewish ancestry in addition to any other ancestry were counted as Ashkenazi Jewish.

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Descriptive statistics were used to characterize participant demographics. Comparisons between participants with positive results and those with negative results utilized Chi-square tests for categorical variables and t-tests for continuous variables. Analyses were performed using the computing environment R (version 3.5.2).

5

Results Of 435 eligible patients in the CASCADE FH Registry Patient Portal, 147 agreed to participate in the lottery, all were offered genetic testing, 122 completed the informed consent process, and 110 underwent genetic testing, giving a net yield of 110/435 (25.3%) of those eligible. The demographics of participants are described in Table 1. The majority were female (75, 68.2%) and Caucasian (91, 82.7%), with a median age of 52 years (interquartile range = 40, 61). A total of 83 participants (75.5%) had a self-reported low-density lipoprotein cholesterol (LDL-C) greater than 154, and 54 (49.1%) reported a family history of FH. More than half (64, 58.2%) of participants had a positive genetic test result (Table 1). Comparisons of participant characteristics by genetic test result type are shown in Table 2. The mean age at time of genetic testing was slightly younger in individuals with a positive result (48.5 years; SD 13.3) than those with a negative result (53.5 years; SD 12.5; p-value = 0.04). Participants with a positive result also reported a younger age at FH diagnosis (28.5 years; SD 13.9) compared to those with a negative result (45.1 years; SD 14.4; p-value = <0.001). Positives were more likely to report having a family history of FH compared to negatives (49.1% vs. 15.2%; p-value = <0.001) and the distribution of LDL-C levels varied between result types (pvalue = 0.03). Among those with a positive result, the majority had a pathogenic or likely pathogenic variant in LDLR (59, 92%), followed by APOB (5, 8%). No pathogenic or likely pathogenic variants were identified in PCSK9 (Table S1). The pathogenic variant with the highest frequency in LDLR was c.6del (p.Trp4Glyfs*202) and was identified in five participants (Table S1). LDLR c.6del causes a frameshift and premature translation stop signal, which is expected to result in an absent or non-functional protein product.10 A single pathogenic variant in APOB, c.10580G>A

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(p.Arg3527Gln), was also identified in five participants (Table S1). This single nucleotide variant (SNV) is a missense variant in the β2-domain of APOB and may affect protein conformation and impair binding to LDLR.10 Overall, SNVs accounted for 68.8% (n = 44) of all pathogenic and likely variants, whereas insertions and deletions and structural variants accounted for 18.8% (n = 12) and 12.5% (n = 8), respectively (Table S1). A total of 11 (10.0%) participants had a variant of uncertain significance (VUS), irrespective of additional pathogenic or likely pathogenic variants (Table S2). Of note, we identified a novel pathogenic structural variant involving the promoter region and exon 1 in LDLR, c.[-203_67+26delins AGG; 67+3241_67+4720delins(-192_33)inv] (Table S1), in a 33 year old Caucasian male with no family history of FH, cardiovascular disease, or sudden cardiac death. This participant was diagnosed with FH (LDL-C 420 mg/dL) at the age of 32, after undergoing emergency quadruple bypass surgery. The lack of a family history of cardiovascular disease suggests that this complex rearrangement may exhibit incomplete penetrance or arose de novo. LDLR c.[-203_67+26delins AGG; 67+3241_67+4720delins(192_33)inv] is not listed in the Exome Consortium browser or the Genome Aggregation Database and has not been previously published in the literature. Family cascade screening was offered to the participant’s parents free of charge, but they have not yet undergone genetic testing. First-degree relatives of all participants who had a positive genetic test result were eligible for free genetic testing and counseling. Only three first-degree relatives agreed to genetic testing, all of which were female, Caucasian, and from different (probands), completed family cascade screening. Of those, two reported a previous diagnosis of FH (LDL-C 250-329 mg/dL and ≥ 330 mg/dL) and had a positive genetic test result for LDLR c.427T>C (p.Cys143Arg) and

7

LDLR c.1783C>T (p.Arg595Trp), respectively. The third did not report a previous diagnosis of FH (LDL-C ≤ 154 mg/dL) and had a negative genetic test result.

8

Discussion About one-third of clinically diagnosed FH patients showed spontaneous interest in receiving free genetic testing with three quarters of those sending in a specimen for testing. The yield from those tested was 58% with positive tests for an FH gene. Higher LDL-C levels, younger age, and the presence of a reported positive family history were more common with those having a positive test. Disappointingly, only four people (from three probands) considered cascade screening with three completing the process. This result is not surprising given that prior work suggests that relying on the proband to encourage cascade screening is not effective.11 While those with positive genetic confirmation of FH can be unambiguously diagnosed with the condition, patients may become confused when a phenotypic diagnosis is clear, but the genetic test result is negative.12 Phenotypic FH can be established using scoring systems such as Simon Broome, MEDPED, and the Dutch Lipid Clinics algorithm. However, overlap of the FH phenotype with polygenic hypercholesterolemia and severely elevated lipoprotein(a) concentrations may result in ambiguity.13,14,15 The use of genetic testing in this study yielded a positive genetic confirmation of FH in over half of our study population. This yield compares favorably with clinical series where Simon Broome and Dutch Lipid Clinic scores were evaluated in probands suspected of having FH.16,17 In one study, for those with definite FH by diagnostic score, yields were high (73%) while those with possible FH (lower scores) the yields were lower (27%).16 A second study showed a direct relationship between the magnitude of the score and genetic testing yield.17 This study identified a novel pathogenic structural variant in LDLR in a 33 year-old Caucasian male who had no family history of FH and/or cardiovascular disease. This variant would have likely gone undetected using methodologies that target coding sequences at low

9

sampling density, such as array comparative genomic hybridization and multiplex ligationdependent probe amplification. This case highlights the usefulness of next generation sequencing-based testing to make a genetic diagnosis of FH. Hopefully, a recent scientific statement from the FH Foundation, published after the onset of this study, will improve acceptance of genetic testing.1 This statement defines those patients who are candidates for FH genetic testing; the presence of a pathogenic variant in an FH gene requires cascade testing in family members and initiation of lipid lowering treatment according to established guidelines, often at a young age to prevent lifelong exposure to high LDL-C.1 For those with elevated LDL-C and a positive family history, with a negative genetic test or without testing, treatment to lower risk remains important.12 The yield from family cascade screening in this study was poor. In other Western countries, organized cascade testing programs typically identified at least two at-risk relatives for each proband.18,19 However, success for these programs depended on a centrally coordinated service, which included trained personnel making contact with families, and having genetic testing and counseling integrated into existing medical services.18 One genetic testing/cascade screening study has been conducted in the United States.20 These investigators showed strong interest in genetic testing in probands identified by either presence of family history of early cardiovascular events or elevated LDL cholesterol; there was some success in cascade screening. In our study, barriers to family cascade screening such as reluctance to contact family members, fear of genetic discrimination, and fear of knowledge gaps by the identified probands (as they provide medical information to family members without medical support) may have contributed to the lack of recruitment of potentially affected relatives.7 The use of electronic communication

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from both the patient portal and Color genomics may also have added confusion or limited responses. Our study is limited by demographics and health history information being self-reported, which may have resulted in over- or under- estimating certain characteristics in our population. It is likely our analysis was influenced by selection bias. The study population represents CASCADE FH registry Patient Portal participants and reasons for that participation, including the use of electronic communication for information transfer, may have influenced behavior in this study. We did not have systematic data collection for patients who were lost to follow-up after Patient Portal outreach, informed consent, and/or genetic testing kit distribution, making it difficult to comment on the reasons why non-participants did not complete the process. We did not systematically collect feedback from patients about the impact of receiving genetic test results, whether positive, negative, or a variant of unknown significance. We could not compare our results to those that might be obtained in a specialty lipid clinic. LDLRAP was not included in the testing panel. In conclusion, we have demonstrated relatively good uptake of genetic testing for FH in patients with clinically diagnosed FH, when barriers of cost, privacy, and access to testing were removed. However, additional barriers, hinder the uptake of cascade screening in family members of FH patients with positive genetic test results. We also do not know the impact of test results on patients’ understanding of their clinical diagnosis. Healthcare providers should be prepared to counsel patients with positive, negative, and VUS genetic test results to help them better understand their personalized risk and clinical care. Genetic testing is a powerful tool in the care of FH, and more work needs to be done to enhance its utilization in the United States and around the world.1 Future studies should assess

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the particular concerns of patients, family members, healthcare providers, and payers and will help to inform policy, procedures, and protections for all individuals as genetic testing for FH becomes more affordable and accessible. A newly proposed strategy is to perform universal genetic screening on infants during regular health checkups and then test family members of identified patients.18 Consideration should be given to developing a model similar to the Dutch model where cascade screening is supported by a central expert resource rather than relying on patients or busy practitioners to identify, contact, and evaluate relatives.1,5,18,19,20,21

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Acknowledgements We would like to thank Ray Chan, Seon-Kyeong Serra Kim, Annette Leon, Jeroen Van den Akker, and Stephanie Wallace for bioinformatics analysis, variant interpretation, and genetic counseling of the case study. Conflict of Interest SG, AMS, KW, and CDA are employees/officers of the FH Foundation, a 501c3 advocacy and research organization dedicated to improving care for those with familial hypercholesterolemia. CLN, HEW, SL, and AYZ have equity interest and are employed by Color Genomics. IK has no conflict of interest to report

Author Contributions All authors have approved the submitted version of the ms. Gidding: principal investigator, study design, ms. Preparation, data analysis Sheldon: study design, data collection, ms. Review and editing Neben: study design, data collection and analysis, ms. Preparation Williams: data collection, ms. Review and editing Law: study design, data collection, ms. Review and editing Zhou: study design, data collection and analysis, ms. Review and editing Wilemon: funding, study design, ms. Review and editing Ahmed: study design, data collection, ms. Review and editing Kindt: study design, data collection, ms. preparation

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References 1. Sturm A, Knowles JW, Gidding SS, et al. Clinical Genetic Testing for Familial Hypercholesterolemia: JACC Scientific Expert Panel. J Am Coll Cardiol. 2018;72(6):662-680. 2. Nordestgaard BG, Chapman MJ, Humphries SE, et al. Familial hypercholesterolaemia is underdiagnosed and undertreated in the general population: guidance for clinicians to prevent coronary heart disease: consensus statement of the European Atherosclerosis Society. Eur Heart J. 2013;34(45):3478-90(a). 3. Kerr M, Pears R, Miedzybrodzka Z, et al. Cost effectiveness of cascade testing for familial hypercholesterolaemia services in the UK. Eur Heart J. 2017; 38(23):1832-39. 4. Ademi, Z. Watts GF, Pang J, et al. Cascade Screening Based on Genetic Testing is Costeffective: Evidence for the Implementation of Models of Care for Familial Hypercholesterolaemia. J. Clin. Lipidol. 8, 390-400 (2014). 5. Wonderling D, Umans-Eckenhausen MAW, Marks D et al. A cost-effectiveness analysis of the genetic screening program for Familial Hypercholesterolemia in the Netherlands. Semin Vasc Med. 2004;4:97-104 6. Ahmad ZS, Andersen RL, Andersen LH, et al. US physician practices for diagnosing familial hypercholesterolemia: data from the CASCADE-FH registry. J Clin Lipidol. 2016;10:1223-1229. 7. Hendricks-Sturrup RM, Mazor KM, Sturm AC, and Lu CY. Barriers and facilitators to genetic testing for familial hypercholesterolemia in the United States. J Pers Med. 2019;1:E32. 8. https://www.ncbi.nlm.nih.gov/pubmed/31201024) 9. Neben C, Zimmer AD, Stedden W, et al. Multi-gene panel testing of 23,179 individuals for

hereditary cancer risk identifies pathogenic variant carriers missed by current genetic testing guidelines. J Mol Diagn. 2019; 21(4):646-657.

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10. National Center for Biotechnology Information. ClinVar; [VCV000226303.2],

https://www.ncbi.nlm.nih.gov/clinvar/variation/VCV000226303.2 (accessed Oct. 16, 2019). 11. Wurtmann E, Steinberger J, Veach PM, et al. Risk Communication in Families of Children

with Familial Hypercholesterolemia: Identifying Motivators and Barriers to Cascade Screening to Improve Diagnosis at a Single Medical Center. J Genet Couns. 2018. 12. Gidding SS, Champagne MA, de Ferranti SD, et al. The Agenda for Familial Hypercholesterolemia A Scientific Statement From the American Heart Association. Circulation. 2015;132(22):2167-92. 13. Langsted A, Kamstrup PR, Benn M, Tybjaerg-Hansen A, NOrdestgaard BG. High lipoprotein(a) as a possible cause of clinical familial hypercholesterolaemia: a prospective cohort study. 2016;Lancet Diabetes Endocrinol. 2016 Jul;4(7):577-87. 14. Sharifi M, Futema M, Nair D, Humphries SE. Polygenic hypercholesterolemia and cardiovascular disease risk. Curr Cardiol Rep. 2019;21(6):43 15.Berberich AJ, Hegele RA. The complex genetics of familial hypercholesterolaemia.Nat Rev Cardiol 2019;16(1):9-20. 16. Futema M, Whittall RA, Kiley A, et al. Analysis of the frequency and spectrum of mutations recognised to cause familial hypercholesterolaemia in routine clinical practice in a UK specialist hospital lipid clinic. Atherosclerosis. 2013 Jul;229(1):161-8. 17. Haralambos K, Whatley SD, Edwards R, et al. Clinical experience of scoring criteria for Familial Hypercholesterolaemia (FH) genetic testing in Wales. Atherosclerosis. 2015;240(1):190-6. 18. Wald DS, Bestwick JP, Morris JK, Whyte K, Jenkins L, Wald NJ. Child-Parent Familial Hypercholesterolemia Screening in Primary Care, N Engl J Med. 2016;375(17):1628-1637.

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19. Bell DA, Pang J, Burrows S, Bates TR, van Bockxmeer FM, Hooper AJ, et al. Effectiveness of genetic cascade screening for familial hypercholesterolaemia using a centrally coordinated clinical service: An Australian experience. Atherosclerosis. 2015;239:93-100 20. Neuner, J., Dimmock, D., Kirschner, A.L.P. et al. Results and Lessons of a Pilot Study of Cascade Screening for Familial Hypercholesterolemia in US Primary Care Practices. J GEN INTERN MED (2019) doi:10.1007/s11606-019-05485-7 21. Huiiigen R, Kindt I, Verhoeven SB, et al. Two years after molecular diagnosis of familial hypercholesterolemia: majority on cholesterol-lowering treatment but a minority reaches treatment goal. PLoS One. 2010;5(2):e9220.

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Tables Table 1. Population demographics Individuals (n)

Population (%)

110

100

Female

75

68.2

Male

35

31.8

18-30

6

5.5

31-40

22

20.0

41-50

24

21.8

51-65

41

37.3

65+

17

15.5

African

1

0.9

Ashkenazi Jewish

3

2.7

Asian

2

1.8

Caucasian

91

82.7

Hispanic

4

3.6

Multiple Ethnicities

5

4.5

Unknown*

4

3.6

154 or lower

12

10.9

155-189

12

10.9

Total

Sex

Age at Testing (Years)

Ethnicity

LDL-C (mg/dL)

17

190-249

27

26.2

250-329

19

18.4

330 or higher

25

24.3

Unknown*

15

13.6

54

49.1

12

10.9

44

40.0

64

58.2

46

41.8

Yes Family History of FH No Unknown* Positive Test Result Negative

*Unknown includes information not provided. LDL-C, low-density lipoprotein cholesterol.

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Table 2. Comparison of self-reported characteristics among participants with positive a (n=64) and negative (n=46) genetic test result Participant characteristics

%

N

%

64

100.0%

46

100.0%

Female

46

71.9%

29

63.0%

Male

18

28.1%

17

37.0%

Mean (sd)

48.5

(13.3)

53.5

(12.5)

Median (IQR)

49.5

(37, 58.2)

55

(45.2, 63.0)

Mean (sd)

28.5

(13.9)

45.1

(14.4)

Median (IQR)

29

(21, 35)

40

(33, 45)

African

0

0.0%

1

2.2%

Ashkenazi Jewish

2

3.1%

1

2.2%

Asian

1

1.6%

1

2.2%

Caucasian

57

89.1%

34

73.9%

Hispanic

1

1.6%

3

6.5%

Multiple Ethnicities

2

3.1%

3

6.5%

Unknown

1

1.6%

3

6.5%

Less than 154

6

9.4%

6

13.0%

155-189

5

7.8%

7

15.2%

190-249

11

17.2%

16

34.8%

250-329

15

23.4%

4

8.7%

330 or higher

19

29.7%

6

13.0%

I'm not sure

8

12.5%

7

15.2%

Family FH reported

47

73.4%

7

15.2%

No family FH reported

3

4.7%

9

19.6%

Sex

Age at FH dx (years)

Ethnicity

LDL-C Level, range (mg/dL)

Family hx of FH

Negative result (n=46, 41.8%)

N Total

Age at testing (years)

Positive result (n=64, 58.2%)

p-value

0.47a

0.04b

<0.001b

0.37a

0.03a

<0.001a

Unknown family FH 14 21.9% 30 65.2% Abbreviations: SD=standard deviation; IQR = interquartile range; aChi-square test; bt-test

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Supplementary Tables Supplementary Table 1. Pathogenic and likely variants in the population. Gene

cHGVS

pHGVS

Type

Count

APOB

c.10580G>A

p.Arg3527Gln

SNV

5

c.6del

p.Trp4Glyfs*202

Indel

5

SNV

3

SNV

3

SV

3

c.313+2T>C c.682G>T

p.Glu228*

deletion of exons 17-18 c.131G>A

p.Trp44*

SNV

2

c.1474G>A

p.Asp492Asn

SNV

2

c.1775G>A

p.Gly592Glu

SNV

2

c.551G>A

p.Cys184Tyr

SNV

2

c.681C>G

p.Asp227Glu

SNV

2

SV

2

deletion of exon 1 c.1048C>T

p.Arg350*

SNV

1

c.1069G>A

p.Glu357Lys

SNV

1

c.1200C>A

p.Tyr400*

SNV

1

c.1238C>T

p.Thr413Met

SNV

1

c.1285G>A

p.Val429Met

SNV

1

c.1358+2T>A

SNV

1

c.1359-1G>A

SNV

1

LDLR

c.1432G>A

p.Gly478Arg

SNV

1

c.1567G>A

p.Val523Met

SNV

1

20

c.1646G>A

p.Gly549Asp

SNV

1

c.1745T>C

p.Leu582Pro

SNV

1

c.1783C>T

p.Arg595Trp

SNV

1

c.2000G>A

p.Cys667Tyr

SNV

1

c.259T>G

p.Trp87Gly

SNV

1

c.284G>T

p.Cys95Phe

SNV

1

c.296C>G

p.Ser99*

SNV

1

c.400T>C

p.Cys134Arg

SNV

1

c.427T>C

p.Cys143Arg

SNV

1

c.530C>T

p.Ser177Leu

SNV

1

c.589T>G

p.Cys197Gly

SNV

1

c.662A>G

p.Asp221Gly

SNV

1

SNV

1

c.694+1G>A c.798T>A

p.Asp266Glu

SNV

1

c.820del

p.Thr274Hisfs*96

Indel

1

c.[1690A>C;2397_2405del]

p.[Asn564His;Val800_L eu802del]

Indel

1

c.2416dup

p.Val806Glyfs*11

Indel

1

c.303del

p.Glu101Aspfs*105

Indel

1

c.340_344del

p.Phe114Leufs*14

Indel

1

21

c.654_656del

p.Gly219del

Indel

1

c.677_681dup

p.Glu228Leufs*39

Indel

1

c.[203_67+26delinsAGG;67+3241_67 +4720delins(-192_33)inv]

SV

1

deletion of exons 16-18

SV

1

deletion of the promoter and exon 1

SV

1

SNV, single nucleotide variant. Indel, insertions or deletion. SV, structural variant. Supplementary Table 2. VUS in the population. Gene

cHGVS

pHGVS

Type

Count

c.10793C>T

p.Ala3598Val

SNV

1

c.1133C>T

p.Thr378Ile

SNV

1

c.133C>G

p.Arg45Gly

SNV

1

c.4532C>T

p.Thr1511Ile

SNV

1

c.9633C>A

p.Asn3211Lys

SNV

1

c.9779T>C

p.Val3260Ala

SNV

1

c.1529C>T

p.Thr510Met

SNV

1

c.1533A>T

p.Leu511Phe

SNV

1

c.1640T>C

p.Leu547Pro

SNV

1

c.299A>T

p.Asp100Val

SNV

1

c.482T>C

p.Ile161Thr

SNV

1

APOB

LDLR

PCSK9

SNV, single nucleotide variant.

22

Highlights • • •

In the USA, there is interest in genetic testing when offered for free and online. In those diagnosed with FH by a lipidologist, about 58% had a positive test. Uptake of cascade screening by family in those with a positive test was minimal.