ORPHA:96186
Maternal uniparental disomy of chromosome 20 syndrome
Also known as: Maternal UPD(20) · UPD(20)mat
Clinical definition (Orphanet)
Maternal uniparental disomy of chromosome 20 (UPD 20) is a very rare chromosomal anomaly in which both copies of chromosome 20 are inherited from the mother. The main feature described is and postnatal growth retardation. Microcephaly, minor features and psychomotor have been occasionally reported. Maternal UPD20 is most often ascertained by a mosaic trisomy 20 pregnancy.
How rare: <1 / 1 000 000 — fewer than one in a million. In a city the size of Kolkata, that might mean on the order of fifteen people.
Is anyone studying this?
70
70 papers have ever been published on this condition (under this name). For scale, breast cancer has over 700,000. Median papers in the last 10 years for a rare disease in this dataset (publications denominator n=183) is 38.
70 papers since the earliest indexed year in this search — median last-10-year count for a rare disease in this dataset is 38 (publications denominator n=183).
59 in the last 10 years · high confidence · 59.8th percentile (publications denominator)
Is a treatment being tested?
0
trials for this specific condition
No interventional trial testing a treatment matched this specific condition name on ClinicalTrials.gov (observational studies and pan-disease registries are listed separately when present).
Data as of 26 July 2026
0
no matched trials for uniparental disomy, the broader category this belongs to either
Parent-category matching found a broader label but no interventional trials under it. How we count trials.
No matched interventional trials. This is true for 59.2% of diseases in the trials denominator (151 of 255). Here are the researchers publishing on it.
high confidence · 29.6th percentile (trials denominator)
Do we know what causes it?
Not yet — the cause hasn't been pinned down in GenCC.
No strong gene–disease assertion joined for this Orphanet entity.
Who's working on it?
483
Distinct author names in 70 sampled papers — named people below.
Who's working on it?
No interventional trial matched this name; these authors publish on it in the sampled literature — a practical starting point for contact.
- 01Kagami M16 papers · 2026
Department of Molecular Endocrinology, National Research Institute for Child Health and Development, Tokyo, Japan.
Papers in Europe PMC - 02Eggermann T14 papers · 2024
Medical Faculty, Institute of Human Genetics, RWTH Aachen University, Aachen, Germany.
Papers in Europe PMC - 03Ogata T11 papers · 2024
Department of Molecular Endocrinology, National Research Institute for Child Health and Development, Tokyo, Japan.
Papers in Europe PMC - 04Fukami M10 papers · 2026
Department of Molecular Endocrinology, National Research Institute for Child Health and Development, Tokyo, Japan.
Papers in Europe PMC - 05Matsubara K9 papers · 2024
Department of Molecular Endocrinology, National Research Institute for Child Health and Development, Tokyo, Japan.
Papers in Europe PMC - 06Nakamura A8 papers · 2024
Department of Molecular Endocrinology, National Research Institute for Child Health and Development, Tokyo, Japan.
Papers in Europe PMC - 07Russo S8 papers · 2025
Laboratory of Cytogenetics and Molecular Genetics, Istituto Auxologico Italiano IRCCS, Milano, Italy.
Papers in Europe PMC - 08Inoue T6 papers · 2024
Department of Molecular Endocrinology, National Research Institute for Child Health and Development, Tokyo, Japan.
Papers in Europe PMC - 09Tannorella P6 papers · 2025
Research Laboratory of Medical Cytogenetics and Molecular Genetics, IRCCS Istituto Auxologico Italiano, Milano, Italy.
Papers in Europe PMC - 10
Recruiting interventional trials
Trials testing a treatment from the matched ClinicalTrials.gov set
No interventional trial testing a treatment was found for this specific condition name on ClinicalTrials.gov.
Broader category uniparental disomy also has no matched interventional trial. See who's working on it above — people publishing on this disease are often the practical next contact when no trial is listed.
Where to find support
We do not yet link condition-specific patient organisations. These umbrella groups support undiagnosed and ultra-rare families:
India — NPRD
Last verified 2026-07-26This ORPHAcode is not on our curated NPRD list (direct or Mondo-parent match). That does not decide clinical eligibility; families in India should ask a notified Centre of Excellence about current coverage.
Hand-curated for this project. ORPHAcode mappings are best-effort and may be incomplete or imprecise for umbrella categories. Parent (Mondo) matches mean the policy lists a broader category — confirm eligibility with a Centre of Excellence. Financial entitlements summarised from public policy statements and may change. This is not official government guidance.
How we counted this
Europe PMC query (preferred label + any corrected label + Orphanet and Mondo exact synonyms, stoplisted; unioned with resolved MeSH labels when available). UMLS / OMIM / NCIT cross-references are stored below but are not added to the query string.
"Maternal uniparental disomy of chromosome 20 syndrome" OR "Maternal UPD(20)" OR "UPD(20)mat" OR "maternal uniparental disomy of chromosome type 20"
ClinicalTrials.gov query (quoted phrases + MeSH via query.cond, plus recall-expansion terms when used):
"Maternal uniparental disomy of chromosome 20 syndrome" OR "Maternal uniparental disomy of the chromosome 20 syndrome" OR "Maternal UPD(20)" OR "UPD(20)mat" OR "maternal uniparental disomy of chromosome type 20" OR "maternal uniparental disomy of the chromosome type 20"
Study-type breakdown: 0 interventional · 0 observational · 0 expanded access. Only interventional studies enter the trial headline.
Cross-references (from Mondo): OMIM:617352 UMLS:C4275029
Query health: ok — strategies attempted: phrase; with hits: phrase
Run this search on ClinicalTrials.gov
Confidence reasoning
- Preferred label is multi-word and distinctive
- No synonyms dropped by stoplist
- No label/synonym collisions with other diseases in this corpus