Z15.1 ICD-10-CM Code: Genetic susceptibility to epilepsy and neurodevelopmental disorders

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for Z15.1 in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2026Effective: October 1, 2025

Notes without a marker are published on Z15.1 itself; “inherited from” names the category or block whose note applies here.

Coder workflow for Z15.1

MedCoder structured workflow — derived from this code’s own official record

Before you code Z15.1

1. Confirm the reason for the encounter this Z code records: the circumstance it records. Check whether the code may be reported as first-listed or principal — some Z codes are limited to one position — and do not report a history or status code for a condition documented as current. Z code categories and their reporting positions (Guidelines I.C.21.c, I.C.21.c.15).

   Guide: Z codes as principal or first-listed diagnosis →

2. Check the Excludes1 note: if the documentation supports a condition named there, do not simply proceed with Z15.1. Excludes1 conditions are not reported together with this code unless the record shows they are unrelated (Guidelines I.A.12.a).

   See the official tabular notes

Choose the right path

1. Does the documentation support a condition named in Z15.1’s Excludes1 note?
   Yes → Do not simply proceed: review the excluded code. Both are reported only when the record shows the two conditions are unrelated.
   No → Continue.

Consider Z15.1. Then work the Use Additional Code note and review the Code Also note, and confirm the code is valid for the date of service in the Verify section.

Documentation check

The provider’s diagnostic statement

Codes are assigned from the provider’s documented diagnosis, not from clinical criteria, test values or a medication list (Guidelines I.A.19).

The conditions the Use Additional Code note names

Reported with this code when documented; a conditional instruction (“if applicable”, “if known”) applies only when the record supports it.

The reason for the encounter

Whether the code records the encounter’s purpose, a status, or a history — and whether it may be first-listed (Guidelines I.C.21.c).

Official instructions as workflow

• Excludes1 — check before selecting Z15.1(1 note)

  Coding workflow: If the documentation supports a condition named in this note, do not simply proceed with Z15.1: the two are not reported together. The one exception is when the record shows the two conditions are unrelated to each other.

  See the official tabular notes · Guidelines I.A.12.a

• Use Additional Code — after identifying Z15.1(1 note)

  Coding workflow: Check whether the documentation supports the additional code(s) the note names, and report them with Z15.1 when it does. Where the instruction is conditional (“if applicable”, “if known”), it applies only when the record documents the condition.

  See the official tabular notes · Guidelines I.A.13

• Code Also — related condition(8 notes)

  Coding workflow: Review the related condition when both are documented and the instruction applies. A Code Also note does not fix sequencing; the order follows the circumstances of the encounter.

  ReviewG93.45, F80, F81, G40, F88, F84

  See the official tabular notes · Guidelines I.A.17

Coding decision scenarios

Pattern scenarios for this code’s structure — decision rules, not clinical cases

Every row is derived from this code’s own record — its title, tabular notes, 7th-character family and same-category siblings — with fixed MedCoder wording; nothing is inferred about a patient. The official notes and guideline text are in the sections each row links to, and they control.

Indexed Clinical Terms (2)

Official source data — entries quoted as published, in the Index’s own lookup phrasing

Clinical term phrases from the official ICD-10-CM Index to Diseases and Injuries that map to this code. These are alphabetic-index entries shown as the Index writes them — lookup phrasing, not necessarily the wording of a final diagnosis.

• Genetic, susceptibility to disease NEC, epilepsy
• Genetic, susceptibility to disease NEC, neurodevelopmental disorders

Official Coding Guidelines

Official source data — quoted verbatim from the CMS/NCHS Official Guidelines

Official source data — quoted verbatim from the CMS/NCHS Official Guidelines

Verbatim excerpts from the ICD-10-CM Official Guidelines for Coding and Reporting (CMS/NCHS) that govern this code.

Don’t confuse Z15.1 with…

MedCoder analysis — pairs from this code’s official notes, distinctions written by MedCoder

The codes most likely to be picked instead of Z15.1 — named in its own official notes, or sharing its laterality or encounter family — with what separates them and which documentation moves the case. Each links to the full comparison.

• Q90— Excludes1 conflict (Excludes1 — generally not reported together)

  Not coded here — the tabular list excludes this pair for the same encounter.

  Not reported together with this code, except where the two conditions are documented as unrelated.

  What moves you there: Documentation of chromosomal anomalies moves the case to Q90; the two are not reported together unless documented as unrelated.

  Full comparison: Z15.1 vs Q90 →

• Q99— Excludes1 conflict (Excludes1 — generally not reported together)

  Not coded here — the tabular list excludes this pair for the same encounter.

  Not reported together with this code, except where the two conditions are documented as unrelated.

  What moves you there: Documentation of chromosomal anomalies moves the case to Q99; the two are not reported together unless documented as unrelated.

  Full comparison: Z15.1 vs Q99 →

Relationships are read from this code's own official notes, its laterality siblings and its encounter family; the wording of each distinction is MedCoder editorial, and the documentation named in each “what moves you there” line is the official note phrase or sibling title itself. Source: CMS ICD-10-CM tabular instructional notes; ICD-10-CM Official Guidelines, Section I.A.12.a.

Decision Points

The directives on this code's own record, as a pre-claim checklist.

1. 1 Use Additional Code instruction — report the named additional code(s) when the documentation supports them. See the Use Additional Code notes
2. 8 Code Also notes — a second code may apply; the guidelines leave its sequencing to the circumstances of the encounter. See the Code Also notes
3. 1 Excludes1 entry — codes named there are generally not reported together with this code (Guidelines I.A.12.a). See the Excludes1 notes

Checklist rows are derived from this code's own official directives; the wording of each check is MedCoder editorial. The official notes themselves are in the sections each row links to.

Verify Before Coding

• Principal-diagnosis restriction. The Medicare Code Editor lists this code as unacceptable as a principal diagnosis: it describes a circumstance influencing health status rather than a current illness or injury being treated. It is valid as a secondary diagnosis.

From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim in Claim Check.

Relationships & Classification

MedCoder structured relationships — computed from published CMS and AHRQ datasets

MS-DRG Grouper Relationships (FY2026)

Potential MS-DRG participation — not a DRG assignment.

FY2026 MS-DRG: not on the CMS CC/MCC list — as a secondary diagnosis this code does not change MS-DRG severity for that release.

Named in the grouper logic of 1 MS-DRG: DRG 951 (MDC 23).

From the CMS MS-DRG Definitions Manual (Appendices B and C). Actual DRG assignment depends on the complete claim.

Clinical classification (AHRQ CCSR):FAC029 — Genetic susceptibility to disease.

Clinical Classifications Software Refined (CCSR) for ICD-10-CM Diagnoses. Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality.

Related Codes

Principal diagnosis restriction (Medicare Code Editor)

Not acceptable as a principal diagnosis on an inpatient claim.

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Genetic susceptibility to disease).

Z15.01 — Genetic susceptibility to malignant neoplasm of breast, Z15.02 — Genetic susceptibility to malignant neoplasm of ovary, Z15.03 — Genetic susceptibility to malignant neoplasm of prostate, Z15.04 — Genetic susceptibility to malignant neoplasm of endometrium, Z15.05 — Genetic susceptibility to malignant neoplasm of fallopian tube(s), Z15.060 — Genetic susceptibility to colorectal cancer, Z15.068 — Genetic susceptibility to other malignant neoplasm of digestive system, Z15.07 — Genetic susceptibility to malignant neoplasm of urinary tract, Z15.09 — Genetic susceptibility to other malignant neoplasm, Z15.2 — Genetic susceptibility to obesity, Z15.3 — Genetic susceptibility to kidney disease, Z15.81 — Genetic susceptibility to multiple endocrine neoplasia [MEN], Z15.89 — Genetic susceptibility to other disease, Z17.0 — Estrogen receptor positive status [ER+], Z17.1 — Estrogen receptor negative status [ER-], Z17.21 — Progesterone receptor positive status, Z17.22 — Progesterone receptor negative status, Z17.31 — Human epidermal growth factor receptor 2 positive status, Z17.32 — Human epidermal growth factor receptor 2 negative status, Z17.410 — Hormone receptor positive with human epidermal growth factor receptor 2 positive status, +5 more

Same Index main term, other category

The ICD-10-CM Index to Diseases and Injuries files this code under the main term “Genetic”; these codes share that main term but sit in a different category of the Tabular List.

Z14.01 — Asymptomatic hemophilia A carrier (carrier, hemophilia A), Z14.02 — Symptomatic hemophilia A carrier (carrier, hemophilia A, symptomatic), Z14.1 — Cystic fibrosis carrier (carrier, cystic fibrosis), Z14.8 — Genetic carrier of other disease (carrier, specified NEC)

Contextual Map

Every relationship of Z15.1 in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.

Run Z15.1 with these 8 related codes in Claim Check

Hierarchy

• Z00-Z99 — Chapter 21: Factors Influencing Health Status and Contact with Health Services (Z00-Z99) (Z00-Z99)[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• Z14-Z15 — Genetic carrier and genetic susceptibility to disease[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026

Code Also (12)

• F70 — Mild intellectual disabilities[Code Also]: “intellectual disabilities (F70-F79)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• F71 — Moderate intellectual disabilities[Code Also]: “intellectual disabilities (F70-F79)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• F72 — Severe intellectual disabilities[Code Also]: “intellectual disabilities (F70-F79)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• F73 — Profound intellectual disabilities[Code Also]: “intellectual disabilities (F70-F79)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• F78 — Other intellectual disabilities[Code Also]: “intellectual disabilities (F70-F79)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• F79 — Unspecified intellectual disabilities[Code Also]: “intellectual disabilities (F70-F79)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• F80 — Specific developmental disorders of speech and language[Code Also]: “developmental disorder of speech and language (F80.-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• F81 — Specific developmental disorders of scholastic skills[Code Also]: “developmental disorders of scholastic skills (F81.-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• and 4 more

Clinical classification (CCSR)

• FAC029 — Genetic susceptibility to disease[CCSR]— AHRQ CCSR for ICD-10-CM Diagnoses (HCUP)

MS-DRG Grouper

• DRG 951 — OTHER FACTORS INFLUENCING HEALTH STATUS[MS-DRG]: “OTHER FACTORS INFLUENCING HEALTH STATUS (MDC 23)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026

MDC crossing

• MDC 23 — Factors Influencing Health Status and Other Contacts with Health Services[MDC crossing]: “Factors Influencing Health Status and Other Contacts with Health Services — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs. 1,235 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2026

Index entries

• Genetic, susceptibility to disease NEC, epilepsy[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Genetic, susceptibility to disease NEC, neurodevelopmental disorders[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026

Nearest codes (17)

• Z15 — Genetic susceptibility to disease[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• Z15.0 — Genetic susceptibility to malignant neoplasm[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• Z15.01 — Genetic susceptibility to malignant neoplasm of breast[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• Z15.02 — Genetic susceptibility to malignant neoplasm of ovary[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• Z15.03 — Genetic susceptibility to malignant neoplasm of prostate[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• Z15.04 — Genetic susceptibility to malignant neoplasm of endometrium[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• Z15.05 — Genetic susceptibility to malignant neoplasm of fallopian tube(s)[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• Z15.06 — Genetic susceptibility to malignant neoplasm of digestive system[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• and 9 more

Change history

• FY2025 — Added to the code set[Change history]— CMS release files (code change ledger) · icd10cm-fy2025

Sources for this page

Codes, titles, notes, index terms and mappings on this page are transcribed from the datasets below. Relationships MedCoder computed and text MedCoder wrote are labelled where they appear.

Code, title, tabular notes and index terms Official source data

CMS/CDC ICD-10-CM FY2026 tabular list, index and tables, effective October 1, 2025 Release, file and checksum · Publisher’s page

Coding guidelines Official source data

ICD-10-CM Official Guidelines for Coding and Reporting (FY2026), quoted by section Release, file and checksum · Publisher’s page

Claim edits Official source data

CMS Definitions of Medicare Code Edits — v43.1 (April 2026) Release, file and checksum · Publisher’s page

Inpatient payment groups Official source data

CMS MS-DRG Definitions Manual (incl. Appendix B diagnosis index, Appendix C CC/MCC list, Appendix E procedure index) and IPPS Final Rule tables — v43 Release, file and checksum · Publisher’s page

Change history and date-of-service validity Official source data

CMS ICD-10-CM release addenda, ingested release by release into the change ledger Release, file and checksum · Publisher’s page

Comparisons, relationships and the contextual map MedCoder structured relationship

Computed by MedCoder from the tabular notes and tables above; every derived relationship is marked as derived where it appears

Summary and FAQ answers MedCoder explanation

Written by MedCoder to explain the sources above: drafted with AI assistance, checked by a person against the release files, and labelled as MedCoder text where it appears. Not official text.

Labels on this page: Official source data · MedCoder structured relationship · MedCoder explanation. How to read the labels · All data sources and release dates

Nearest Codes in This Family

Official ICD-10-CM classifications closest to Z15.1 in its code family, with their registry titles.

• Z15.06 — Genetic susceptibility to malignant neoplasm of digestive system
• Z15.060 — Genetic susceptibility to colorectal cancer
• Z15.068 — Genetic susceptibility to other malignant neoplasm of digestive system
• Z15.07 — Genetic susceptibility to malignant neoplasm of urinary tract
• Z15.09 — Genetic susceptibility to other malignant neoplasm
• Z15.2 — Genetic susceptibility to obesity
• Z15.3 — Genetic susceptibility to kidney disease
• Z15.8 — Genetic susceptibility to other disease
• Z15.81 — Genetic susceptibility to multiple endocrine neoplasia [MEN]
• Z15.89 — Genetic susceptibility to other disease

View all codes in the Z15 family