Q99.2 Fragile X chromosome

Billable ICD-10-CM code, FY2026. Exempt from present-on-admission (POA) reporting.

Applicable to

• Fragile X syndrome

Risk adjustment (HCC)

• RxHCC V08: HCC 148 — Mild or Unspecified Intellectual Disability/Developmental Disorder

MS-DRG index

Defines the logic of DRG(s) 884 in MDC 19.

Approximate ICD-9-CM (GEMs)

• 759.83 Fragile X syndrome

Code annotations containing back-references to Q99.2

Back-references to Q99

• Code First: D84.81 Immunodeficiency due to conditions classified elsewhere ("chromosomal abnormalities (Q90-Q99)")
• Type 1 Excludes: E25 Adrenogenital disorders ("chromosomal abnormalities (Q90-Q99)")
• Type 2 Excludes: P04 Newborn affected by noxious substances transmitted via placenta or breast milk ("congenital malformations (Q00-Q99)")
• Type 1 Excludes: Q56 Indeterminate sex and pseudohermaphroditism ("pseudohermaphroditism with specified chromosomal anomaly (Q96-Q99)")
• Type 1 Excludes: Z15 Genetic susceptibility to disease ("chromosomal anomalies (Q90-Q99)")

Diagnosis Index entries for Q99.2

• Fragile, fragility › X chromosome
• Syndrome › fragile X

Nearby codes

• Q99 Other chromosome abnormalities, not elsewhere classified
• Q99.0 Chimera 46, XX/46, XY
• Q99.1 46, XX true hermaphrodite
• Q99.2 Fragile X chromosome (this code)
• Q99.8 Other specified chromosome abnormalities
• Q99.81 Usher syndrome
• Q99.811 Usher syndrome, type 1
• Q99.812 Usher syndrome, type 2
• Q99.813 Usher syndrome, type 3