LCBG Intralab Seminar

45 Years of Research on Xeroderma Pigmentosum and Related Diseases at NIH

Presenters:

Kenneth H. Kraemer, M.D. Senior Investigator Chief, DNA Repair Section Laboratory of Cancer Biology and Genetics

John J. DiGiovanna M.D. Senior Research Physician DNA Repair Section Laboratory of Cancer Biology and Genetics

4/9/2020, Thursday, 3:30-4:30 pm Meeting number: 738 498 747 Meeting password: Nciccr1! https://cbiit.webex.com/cbiit/j.php?MTID=me59a7a63c36d3fce6ef6f6e46a5dcfd7 WHY STUDY RARE HUMAN GENETIC DISEASES? • CARE FOR AFFECTED PATIENTS

• DISCOVER MECHANISMS OF DISEASE

• DEVELOP NEW THERAPEUTIC PARADIGMS: USING SMALL NUMBERS OF PATIENTS AT HIGH RISK OF CANCER XERODERMA PIGMENTOSUM (XP) and TRICHOTHIODYSTROPHY (TTD) Both have frequency 1/ million ~300 patients of XP and of TTD in US

XP TTD + Nucleotide Excision Repair + defect: XPD DNA helicase repair / XP transcription + Sun sensitivity + or - TTD ++ Skin pigmentation / cancer - + Ocular abnormalities + - or + Neurological abnormalities + ++ Environmental influence - XP/TTD + Developmental defect ++

3 Mammalian DNA Repair

Gene

Alt-NHEJ

Cancers Xeroderma Cancers (Brca2) Bloom syndrome Cockayne syndrome Pigmentosum Colon NOBEL PRIZES 2015 SCID (immune Rothmund-thomson Immune deficiency Trichothiodystrophy cancer deficiency) syndrome Neurodegeneration Cockayne Werner syndrome syndrome

Slide courtesy W. Bohr Outline • Early history of xeroderma pigmentosum (XP) • NIH studies of XP including new information – premature menopause, thyroid nodules

• NIH studies of trichothiodystrophy (TTD)

• DNA repair/ transcription defect, Readthrough of premature stop codons; Deep phenotyping • Molecular epidemiology – Japan; Big Data FIRST DESCRIPTION OF XERODERMA PIGMENTOSUM 1874 - MORIZ KAPOSI

Moriz Kohn 1837 - 1902 1953 – Watson and Crick describe double helix DNA structure • 1960’s -Reported that UV treatment of DNA in cells produces photoproducts. • The main photoproduct is the covalent cyclobutane pyrimidine dimer (CPD). • DNA repair occurs in Dr. Richard Setlow bacteria.

1968 – James Cleaver describes DNA repair defect in XP UV PHOTOPRODUCTS Kenneth H. Kraemer, M.D. 1969-71 - Harlem Hospital, NY

HEPATITIS, TUBERCULOSIS, TETANUS SHORTAGES OF STAFF, MEDICINE, VENTILATORS, RESOURCES, ICU BEDS, FUNDING Kenneth Kraemer • 1971 Joined United States Public Health service at NIH • Dermatology Branch, National Cancer Institute

2009 DR. JAY ROBBINS Detailed clinical and laboratory description of 15 XP patients – 4 phenotypes 1974 4 complementation groups 1975 DR. DIRK BOOTSMA - ROTTERDAM

Reported 2 complementation groups in xeroderma pigmentosum cells in 1972

1994 5 complementation groups – named in order of increasing residual repair 1975 XP VARIANT - XP4BE

Died age 27 yr of metastatic melanoma

Pol eta defect

PTEN mutations in metastatic melanoma lesions

Wang et al JID 2009 Xeroderma Pigmentosum Distribution • Equally distributed among males • Oldest patient: 75 yr and females; autosomal recessive • Sun sensitivity or freckling (median • Ethnicity; age of onset): 1.5 yr • Middle East • Skin cancer (median age of • Europe onset): 9 yr • Japan • In the past death occurred 30 yr • Africa earlier than in the US general pop. • America • Sun protection may prolong life.

• Frequency: 1:20,000 in Japan • Frequency: 1:1,000,000 in U.S. SITES OF BASAL CELL CARCINOMA AND SQUAMOUS CELL CARCINOMA IN XP AND NORMALS

Similar site distribution of non-melanoma skin cancer in XP patients and normals

Arch Dermatol 130: 1018 (1994) SITES OF MELANOMA IN XP AND NORMALS

Similar site distribution of melanoma skin cancer in XP patients and normals

BUT melanoma site distribution is DIFFERENT from basal cell and squamous cell carcinoma in XP patients and normal - 1994

Arch Dermatol 130:1018 (1994) 40 YEARS FOLLOW-UP - EARLY AGE OF ONSET OF SKIN CANCER IN XERODERMA PIGMENTOSUM

58 yr

10,000-fold increase in skin cancer

33 yr Melanoma induction mechanism different from non-melanoma skin cancer

BUT WE DO NOT UNDERSTAND THE MECHANISM 106 XP patients 1971-2009 OF MELANOMAGeneral population INDUCTIONBradford BY UV et al J Med Gen 2010 40 YEARS FOLLOW-UP OF XERODERMA PIGMENTOSUM AT NIH PROGRESSIVE NEURODEGENERATION with BRAIN ATROPHY

XP12BE – XP-A death age 44

24% (n=25) of the XP patients had neurodegeneration

4 yr 17 yr 41 yr

20 41 yr Infantile sized brain at autopsy yr Lai…DiGiovanna…Kraemer Acta Neuropath Comm 2013

Bradford..DiGiovanna..Kraemer. J Med Gen 2010 40 YEARS FOLLOW-UP OF XERODERMA PIGMENTOSUM AT NIH REDUCED SURVIVAL IN XERODERMA PIGMENTOSUM

30 yr

XP patients with neurological abnormalities have lower survival

BUT WE DO NOT KNOW THE CAUSE OF THE NEUROLOGICAL DAMAGE - Possibly cyclopurines, other oxidative lesions?

Bradford … Kraemer J Med Gen 2010 PREMATURE MENOPAUSE IN WOMEN WITH XERODERMA PIGMENTOSUM Deborah Ob-Gyn NHGRI – Tamura Melissa Merideth Premature menopause DNA repair plays a role in maintenance of normal ovarian function (before age 40) occurred Premature aging in 14/45 (31%) of the XP 23 yr women 18 years or older 9 women had documented primary ovarian insufficiency 2 women had atrophic ovaries on autopsy Merideth, Tamura… Kraemer Obstetrics and Gynecology (2019) EARLY AGE OF THYROID NODULES IN XERODERMA PIGMENTOSUM PATIENTS Radiology CC – Samuel Jamie Marko Kouatcheu DNA repair plays a role in prevention of thyroid16/29 nodules (55%) XP and patients cancer had Premature aging thyroid nodules on ultrasound 1 XP patient had thyroid cancer 30 yr

Thyroid cancer TFG-NTRK1 fusion mutation

Sequencing thyroids from our 8 autopsy patients Future: Unpublished SUN PROTECTION WITH NASA SUIT IN XP

4 yr LONG TERM SUN PROTECTION IN XERODERMA PIGMENTOSUM

Moved to Seattle, WA XP35BE XP34BE 19 yr 23 yr

XP34BE XP35BE 5 yr 1 yr Living in Denver, CO

XPD family COCKAYNE SYNDROME

3 y/o – Died 13 y/o Calcification in Basal Ganglia Questions? PATIENTS WITH XERODERMA PIGMENTOSUM (XP), TRICHOTHIODYSTROPHY (TTD) OR OVERLAP OF BOTH XP/TTD

7 YR F 12 YR F 8 YR M 8 YR M

XP XP XP/TTD TTD Molecular Defects (15)

TFIIE (GTF2E1 GTF2E2)

RNF113A

DiGiovanna and Kraemer JID 2012 TRICHOTHIODYSTROPHY (TTD)

RARE AUTOSOMAL RECESSIVE DISORDER

BRITTLE HAIR WITH LOW SULFUR CONTENT

TIGER TAIL BANDING ON POLARIZED MICROSCOPY

BROAD SPECTRUM OF CLINICAL PHENOTYPES DISTINGUISHING HAIR FINDINGS OF TTD

TRICHORRHEXIS NODOSA CHRISTINE LIANG, MD

RIBBON/TWIST TRICHOSCHISIS

Structural and molecular hair abnormalities in trichothiodystrophy. Liang C, Morris A, Schlücker S, Imoto K, Price VH, Menefee E, Wincovitch SM, Levin IW, Tamura D, Strehle KR, Kraemer KH, DiGiovanna JJ. J Invest Dermatol. 2006 Oct;126(10):2210-6. TTD LITERATURE REVIEW WE SOUGHT ALL PUBLISHED CASE REPORTS OF PATIENTS WITH TTD TO ASSESS THE PREVALENCE OF CLINICAL FEATURES. A TOTAL OF 93 ARTICLES DESCRIBING 112 PATIENTS WERE FOUND.

SALMA (FAGHRI) DE LA FELD, MD

10 YO BOY WITH TTD (XPD)

Faghri S, Tamura D, Kraemer KH, DiGiovanna JJ. Trichothiodystrophy: a systematic review of 112 published cases characterizes a wide spectrum of clinical manifestations. J Med Genet 2008 2008 Oct;45(10):609-21 AGE AT LAST REPORT IN TTD PATIENTS (N = 110) 50

45

40THERE WERE 19 DEATHS BEFORE THE AGE OF 10 YEARS (13 INFECTION RELATED), WHICH IS 20 FOLD HIGHER THAN THE GENERAL US POPULATION 35 32 30 Living Patients (N = 90) Deceased Patients (N = 20) 25

20 Number of Patients 15 25

10 17 5 10 9 7 1 1 0 2 2 2 2 0 - 4 5 - 9 10 - 14 15 - 19 20 - 24 25 - 29 30 - 34 35 - 39 40 - 44 45 - 49 Age Group (years)

Faghri S, et al. J Med Genet 2008 2008 Oct;45(10):609-21 TTD PATIENTS STUDIED AT NIH **

TTD # DECEASED GENOTYPE PATIENTS DECEASED < 10 YRS OLD GTF2E2 1 0 0 TTDA 3 1 0 TTDN1 5 0 0 UNKNOWN 6 0 0 XPD* 21 8 (38%) OF XPD 6/14 (43%) 36 9

* * 2001 - 2016 * XPD = 21/36 (58%) PATIENTS

PHENOTYPE *** XP/TTD 12 1 0 *** 2001 - 2018 TTD PATIENT WITH POOR OUTCOME AFTER DENTAL PROCEDURE

• 3 Y/O TTD PATIENT WITH FAILURE TO THRIVE

• ADMITTED FOR MULTIPLE DENTAL EXTRACTIONS AND RESTORATION OF NUMEROUS CARIES

• RESPIRATORY ARREST 6 HOURS POST-OP

• 6 MONTH ICU: HOSPITALIZATION COMPLICATIONS INCLUDED SEPSIS, PNEUMONIA AND PULMONARY EDEMA

• 8 INTUBATIONS-UNABLE TO BE WEANED FROM RESPIRATOR

• DIED FROM PULMONARY HYPERTENSION AND MULTIPLE ORGAN FAILURE

TTD PATIENTS ARE AT HIGH RISK FOR POOR OUTCOMES AFTER ROUTINE PROCEDURES COMMON FINDINGS AMONG 36 TTD PATIENTS STUDIED AT NIH 2001-20016

ABNORMALITY # PATIENTS HAIR (TT Banding, hair shaft abnormalities) 36 100 % LANGUAGE/MOTOR DELAY 33 92 % MUSCULOSKELETAL 36 100 % Cognitive delay (low IQ) 30 Abnormal audiometry 22 Peripheral osteopenia 25 Dysmyelination (MRI) 17 Short Stature (<3rd %tile) 22 Micrognathia 19 NAIL 33 92 % Koilonychia 20 Microcephaly (<3rd %tile 17 Onhychoschizia 18 Central osteosclerosis 17 BEHAVIOR - Engaging, sociable/happy 31 86 % 97 % OPHTHALMOLOGY 35 ABNORMAL GAIT/UNSTEADINESS 29 81 % infantile Cataracts 16 Bilateral cataracts 15 IMMUNOLOGY - Recurrent infections 28 78 % Respiratory infection 25 Nystagmus 15 Dysgammaglobulinemia 24 Microcornea 13 Ear infection 22 Low abs neutrophil ct 18

SKIN - Xerosis 34 94 % NEONATAL ABNORMALITIES 25 69 % Ichthyosis 26 Low birth weight (<2500 g) 25 Feeding difficulty 23 Collodian membrane 20 Failure to thrive / poor weight gain (<3rd %tile) 21 Palmoplantar keratoderma 5 HEMATOLOGIC 23 64 % Elevated Hb A2 23 PREGNANCY 34 94 % Low MCV 21 Premature birth 22 Preterm labor 15 Pre-eclampsia 7 IUGR 7 Pregnancy-induced HTN 6 CLINICAL FEATURES OF TTD SHORT STATURE: 10 YEARS OLD BOY SHORT STATURE: 10 YEARS OLD BOY HEIGHT: 117 CM = < 1 %-TILE HEIGHT: ~ 117 CM = < 1 %-TILE

FEET GROWTH AND NUTRITION IN CHILDREN WITH TRICHOTHIODYSTROPHY

25 TTD PATIENTS FOLLOWED UP TO 2.7 YRS

MEAN HEIGHT-FOR-AGE Z-SCORE OF -2.75 MEAN WEIGHT-FOR-AGE Z-SCORE OF -2.60

AS CHILDREN AGED, GROWTH PARAMETERS FURTHER SEPARATED FROM STANDARD GROWTH CURVES HEIGHT –FOR-AGE Z-SCORE/YEAR [-0.18± 0.42] WEIGHT-FOR-AGE Z SCORE/YEAR [-0.36 ± 0.51]

PATIENTS WHO DIED DURING FOLLOW-UP (N=5) HAD SIGNIFICANTLY LOWER STANDARDIZED HEIGHT (P = 0.03) AND WEIGHT (P = 0.006), WEIGHT-FOR-LENGTH (<0.0001), AND HIGHER HEART RATES (P =0.02) COMPARED WITH THE REMAINDER OF THE COHORT.

WE RECOMMEND FOLLOWING FOR GROWTH/WEIGHT AND INSTITUTING SUPPLEMENTAL NUTRITION INCLUDING G TUBE FOR PATIENTS UNABLE TO MAINTAIN ADEQUATE GROWTH/WEIGHT

Growth and nutrition in children with trichothiodystrophy. Atkinson EC, Thiara D, Tamura D, DiGiovanna JJ, Kraemer KH, Hadigan C. J Pediatr Gastroenterol Nutr. 2014 Oct;59(4):458-64. WEIGHT-FOR-AGE Z-SCORES OVER TIME FOR EACH SUBJECT

Growth and nutrition in children with trichothiodystrophy. RED HATCHED AREA Z SCORE ± 2.5 Atkinson EC, Thiara D, Tamura D, DiGiovanna JJ, Kraemer KH, Hadigan C. J Pediatr Gastroenterol Nutr. 2014 Oct;59(4):458-64. CLINICAL FEATURES OF TTD

MICROGNATHIA

NAIL CHANGES: ONYCHODYSTROHY

SPOONING ONYCHOSCHISIS COLLODION PRESENTATION OF TTD, CLEARING OVER FIRST WEEK OF LIFE LEAVING MILD XEROSIS IN CHILDHOOD; NORMAL VOLAR SURFACES

8 DAYS –SMALL AMOUNT 1-2 DAYS 4 DAYS “CELLOPHANE-NESS” REMAINING AT KNUCKLES TTD: EXTREME PHOTOSENSITIVITY

COMPLAINED OF PAIN ON UV EXPOSURE

ERYTHEMA AFTER EXPOSURE BEFORE EXPOSURE

TTD343BE: HOMOZYGOUS FOR A 5KB DELETION IN TTDN1

Heller ER, Khan SG, Kuschal C, Tamura D, DiGiovanna JJ, Kraemer KH. Mutations in the TTDN1 gene are associated with a distinct trichothiodystrophy phenotype. J Invest Dermatol 2015 Mar;135(3):734-741 BONE MINERAL DENSITY DEXA (DUAL-ENERGY X-RAY ABSORPTIOMETRY) SCAN CENTRAL Z SCORE WITHIN +/- 2.5 NORMAL OSTEOSCLEROSIS

6.5

TOTAL BODY Z SCORE 6.1 CLINICAL FEATURES OF TTD PROGRESSIVE DIFFICULTY WALKING IN 7 Y.O. GIRL TTD: ABNORMAL BRAIN DEVELOPMENT

DYSMYELINATION ON T2 WEIGHTED MRI

8 y/o NORMAL

DYSMYELINATION

TTD MOTHERS CARRYING AFFECTED FETUSES HAVE DIFFICULT PREGNANCIES

MANSI SARAHAN, MD

Tamura D, Merideth M, DiGiovanna JJ, Zhou X, Tucker MA, Deborah Tamura ,MS RN APNG Goldstein AM, Brooks BP, Khan SG, Oh K-S, Ueda T, Boyle J, Research Nurse Tamura D, Khan SG, Merideth M, DiGiovanna JJ, Tucker MA, Moslehi R, Kraemer KH. Prenat Diagn 2011; 31: 1046–1053. Goldstein AM, Oh K-S, Ueda T, Boyle J, Sarihan M, Kraemer KH. European Journal of Human Genetics (2012) 20, 1308–1310

Hypertension Elevated Liver Enzymes Low Platelets HOW DO WE MAKE SENSE OF THESE DIVERSE DISEASE FEATURES TO BETTER UNDERSTAND THE CLINICAL PHENOTYPES?

GENE/MUTATION ∞ PHENOTYPE

PATIENTS WITH MUTATIONS IN THE TTDN1 GENE HAVE A DISTINCT PHENOTYPE: ELIZABETH HELLER, MD

MORE LIKELY: TO DISPLAY AUTISTIC BEHAVIORS (VS TYPICAL SOCIALLY INTERACTIVE), DELAYED BONE AGE & SEIZURES

LESS LIKELY: TO HAVE LOW BIRTH WEIGHT, COLLODION PRESENTATION, CATARACTS, BRAIN ABNORMAL MYELINATION

Heller ER, Khan SG, Kuschal C, Tamura D, DiGiovanna JJ, Kraemer KH. Mutations in the TTDN1 gene are associated with a distinct trichothiodystrophy phenotype. J Invest Dermatol 2015 135:734-41 TWO UNRELATED CHILDREN HARBORING TWO DIFFERENT HOMOZYGOUS MISSENSE MUTATIONS IN GTF2E2

GTF2E2 – ENCODES TRANSCRIPTION FACTOR IIE THOUGHT TO BE INVOLVED IN DNA MELTING AT THE PROMOTER

Am J Hum Genet 2016 Apr 7; 98(4):627-42. GTF2E2 Mutations Destabilize the General Transcription Factor Complex TFIIE in Individuals with DNA Repair-Proficient Trichothiodystrophy. Kuschal C, Botta E, Orioli D, Digiovanna JJ, Seneca S, Keymolen K, Tamura D, Heller E, Khan SG, Caligiuri G, Lanzafame M, Nardo T, Ricotti R, Peverali FA, Stephens R, Zhao Y, Lehmann AR, Baranello L, Levens D, Kraemer KH, Stefanini M. TTD SUMMARY

TTD IS CHARACTERIZED BY SHORT, BRITTLE, SULFUR DEFICIENT HAIR, EXHIBITS TIGER-TAIL BANDING UNDER POLARIZATION, AND HAS A SPECTRUM OF SPECIFIC HAIR SHAFT ABNORMALITIES.

THERE IS A WIDE SPECTRUM OF DEVELOPMENTAL ABNORMALITIES WITHIN TTD, AND IN ADDITION, THERE ARE OVERLAP SYNDROMES SUCH AS XP/TTD.

OCULAR, IMMUNOLOGIC AND PREGNANCY ABNORMALITIES ARE COMMON IN TTD.

THERE IS A HIGH MORTALITY AT YOUNG AGE.

PATIENTS HAVE DEFECTS IN XPD, XPB, TTD-A, TTDN1, GTF2E2 AND RNF113A (X-LINKED) . WHY IS IT IMPORTANT TO DIAGNOSE TTD?

EARLY DIAGNOSIS MAY HAVE IMPORTANT CLINICAL IMPLICATIONS HIGH MORTALITY FROM INFECTION

MOST PATIENTS HAVE DEVELOPMENTAL DELAY / INTELLECTUAL IMPAIRMENT SPECIAL EDUCATION AND SUPPORTIVE MEASURES

MOTHERS WHO HAVE HAD PREGNANCY COMPLICATIONS CAN BE MONITORED DURING FUTURE PREGNANCIES

GENETIC TESTING / PRENATAL DIAGNOSIS CAN BE CONSIDERED Questions? UV HYPERSENSITIVITY OF XERODERMA PIGMENTOSUM AND COCKAYNE SYNDROME CELLS DNA REPAIR – THE LIFEGUARD OF THE GENE POOL NUCLEOTIDE EXCISION REPAIR PATHWAY

XP-C & XP-E

XPA DAMAGE RECOGNITION/VERIFICATION BEFORE TFIIH BINDING BASAL TRANSCRIPTION

XP-B & XP-D UNWIND THE DAMAGED AREA

POLYMERASE AND LIGASE FILL THE GAP

XP-F & XP-G MAKE INCISIONS ON EITHER SIDE OF THE DAMAGE

DiGiovanna and Kraemer JID 2012 XP: Defect in nucleotide excision repair

Complementation Gene Locus Percentage Group XPA XPA 9q22.3 29.4%; most common in Japan

XPB XPB 2q21 0.5% ERCC3 XPC XPC 3p25 27.3%; most common in US XPD XPD 19q13.2-q13.3, 15.0% most common with ERCC2 10q11 neurologic disease XPE DDB2 11p12-p11 1.1% XPF XPF 16p13.3-p13.13 1.6% ERCC4 XPG RAD2 13q33 1.1% ERCC5 XPV POLH 6p21.1-p12 24.1%

Modified from: Kraemer KH et al. Xeroderma Pigmentosum. Arch Dermatol 1987; 123: 241-250. “READTHROUGH” MECHANISM OF AMINOGLYCOSIDES • Primary premature termination codons (PTC) cause ~12% of human genetic disorders. • PTC (stop codons) can cause elongation arrest, or the mRNA is degraded by nonsense mediated decay.

E

Read-through Zingman et al., 2007 • Aminoglycosides bind to ribosomal RNA leading to conformational changes that can result in tRNA mis-pairing to mRNA with READTHROUGH of stop codons. • We previously have shown that XPC patients with ~ 2% normal message had mild disease (Khan …Kraemer, Hum Mol Gen 2004). • Topical gentamicin increased type VII collagen, and reduced blisters in 5 patients with epidermolysis bullosa with PTC – Woodley et al JCI 2017 • We have fibroblasts from 18 XP-C patients in our collection with premature termination codons. Kuschal .DiGiovanna… Kraemer PNAS 2013

56 GENETICIN AND GENTAMICIN AMLEXANOX INCREASED INDUCE XPC PROTEIN LOCALIZATION or REDUCED XPC mRNA EXPRESSION IN UV-IRRADIATED XP-C CELLS in XP-C CELLS

UV UV + Geneticin UV + Gentamicin Sikandar Laila Khan Al-Eryani

Plan to test cells from individual patients before treatment –

TGA-T 1,2 PRECISION MEDICINE XP62DC

TGA-G 1,2 Treatment with aminoglycosides Treatment with amlexanox XP198BE increased DNA repair in cells from SOME increased XPC mRNA in cells from SOME XP patients with premature stop codons XP patients with premature stop codons

Kuschal .… Kraemer PNAS 2013 Unpublished

57 DEEP PHENOTYPING with HIERARCHICAL CLUSTERING of CLINICAL FEATURES ASSISTS IN PROGNOSIS TTDN1 66 patients with ERCC2 (XPD) mutations: patients have 30 XP, 13 XP/TTD, 23 TTD distinct phenotype Elizabeth JID 2014 Heller

Jennifer Pugh

TTD patients have a greater reduction in survival than the XP or XP/TTD patients George Nelson Unpublished

58 DEEP PHENOTYPING with HIERARCHICAL CLUSTERING of CLINICAL FEATURES ASSISTS IN PROGNOSIS 66 patients with ERCC2 (XPD) mutations: 30 XP, 13 XP/TTD, 23 TTD 221 clinical and laboratory features

Hierarchical clustering and principal component analysis of clinical and laboratory features may be a model for evaluating complex diseases

Prognostic Features for TTD Survival • Hierarchical clustering • Low birth weight • Principal component • Infantile cataracts analysis • Cryptorchidism (males) • Cox model • Micro-cornea • Bootstrap replicates • Low absolute reticulocyte count • Peripheral osteopenia – x-ray

59 1 million carriers of the XPA mutation in Japan

Cancer risk of XPA heterozygotes is not known USE OF BIG DATA TO ESTIMATE PREVALENCE OF DEFECTIVE DNA REPAIR VARIANTS IN THE US POPULATION Question: Do databases of exome sequences reliably correlate with the prevalence of individuals with defective DNA repair?

Large exome databases revealed high frequencies of 2 DNA repair gene mutations associated with xeroderma pigmentosum

Jennifer Pugh Pugh … Kraemer JAMA Derm 2018

61 PREDICTED FREQUENCY OF XP IN THE UNITED STATES

These frequencies estimate the presence of more than 8,000 people with xeroderma pigmentosum in the US who are homozygous for these mutations, yet only 4 individuals were clinically identified. CONCLUSION: Discrepancy between large number of XP genotypes in database and known number of XP patients.

HYPOTHESIS: Unsuspected mutations in known skin cancer genes may be responsible for some of the high frequency of skin cancers in the general population. Pugh … Kraemer JAMA Derm 2018

62 WHAT NEXT?

Question: How to explain large discrepancy between predicted and observed frequencies of XP homozygotes? Affected patients may have mild phenotype, different phenotype, incomplete penetrance, late onset of neurological degeneration. Modifier genes may affect phenotype.

Future: A. Identify subjects with these mutations and perform detailed clinical examination and parallel Whole Genome Sequencing (Max Lee – LCBG) Access to new large groups of subjects who had exome sequencing: NIH resource ~10,000; Geisinger “My Code” ~200,000 (Alisa Goldstein, Douglas Stewart – DCEG, NCI); NIH “All of Us” goal 1 million B. XP patients seen in our clinic – Perform Whole Exome Sequencing – look for modifier genes (Max Lee – LCBG) C. Mouse models - Examine identified mutations (Kent Hunter - LCBG)

63 NIH DNA REPAIR INTEREST GROUP • Co-chair, with Dr. V. Bohr (NIA) established 1985

• Monthly videoconferences - WEBEX • 8 linked sites across US • >250 lectures archived at http://videocast.nih.gov • Original tapes archived by National Library of Medicine to preserve for historical and educational value

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64 Long Time Partners

OUR PATIENTS AND THEIR FAMILIES THANK YOU

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