Start here · For families and clinicians
Understanding dysmelia.
Dysmelia is the generic term for all types of congenital limb differences: limbs that formed differently, incompletely or not at all before birth. It concerns about 5 in 10,000 people. Behind the word are many distinct conditions; the guide below introduces the main ones in plain language, with links to Orphanet, the European reference database for rare diseases.
01 · The conditions
Many conditions, one community.
Find the pages that concern you
Three questions to narrow the list below. This helper does not diagnose anything: only a clinician or geneticist can. It simply helps you find the right Orphanet pages to read and to bring to your consultation.
24 of 24 conditions match ·
Amelia of the upper limb
complete or near-complete absence of one or both arms, without other malformations.
Amelia of the lower limb
complete or near-complete absence of one or both legs, without other malformations.
Amniotic band syndrome
bands of amnion constrict developing limbs before birth.
Brachydactyly
disproportionately short fingers or toes.
Umbrella term; see the specific types on Orphanet.
Cenani-Lenz syndrome
fused fingers and forearm bones give the hand a mitten-like form.
Microgastria–limb reduction
a small stomach together with limb reduction defects.
Phocomelia
intercalary limb deficiency; the hands or feet attach close to the trunk.
Poland syndrome
underdeveloped chest muscle with hand differences on the same side.
Symbrachydactyly
short, webbed or missing fingers, usually on one hand; not inherited.
Not an Orphanet entity as such: Orphanet lists only the rare form affecting hands and feet, ORPHA:1570 ↗.
Each card links to the condition’s page on Orphanet, the European reference database for rare diseases, through its permanent ORPHAcode; the codes were carried over from the previous DysNet site and re-verified in August 2026. Know one we have not covered, or have information to add? Tell us.
02 · Not alone
The associations that know your condition.
Whatever the diagnosis, a member association near you has walked this road: from Poland-syndrome groups in France and Italy to thalidomide organisations across the world. Find yours.
Annex · Prevalence
How frequent is each condition?
Two columns, two kinds of source. Orphanet gives each rare disease a prevalence class and, where available, a mean estimate; it is the reference for named syndromes. Population studies fill the gaps for the conditions Orphanet does not count (the amelias, polydactyly, syndactyly, brachydactyly) and cross-check the others. Every figure was checked against its original publication in September 2026.
| Condition | Orphanet | Population studies |
|---|---|---|
| All limb reduction defects | Not an Orphanet entity | 4.5 per 10,000 births in Europe, 2003-2012 (EUROCAT)9; Norway 4.4 (1970-2016)9; northern Netherlands 6.9 (1981-2010)3; upper-limb deficiencies 5.6 per 10,000 births in Finland6 |
| Adams-Oliver syndrome | 1-9 / 1 000 000 prevalence, mean 0.44 per 100,000 (Worldwide); about 398 cases described ORPHA:97411 | No population figure found |
| Amelia | No epidemiological data published ORPHA:102711 | 1.41 per 100,000 births (326 cases in 23.1 million births, 20 registries, 1968-2006)1; Finland: 2.43 per 100,000 births, 0.63 per 100,000 live births (1993-2008)2 |
| Amelia of the upper limb | No epidemiological data published ORPHA:29496711 | Upper limbs in 54% of single-limb amelia cases1; 26% of amelia cases in Finland2 |
| Amelia of the lower limb | No epidemiological data published ORPHA:29496911 | Lower limbs in 70% of amelia cases in Finland2 |
| Amniotic band syndrome | 1-9 / 100 000 birth prevalence, mean 5.3 per 100,000 (Europe) ORPHA:29500011 | Upper-limb defects from constriction bands: 51 in 753,342 births, about 0.7 per 10,000 (Finland)6 |
| Brachydactyly | No ORPHAcode (umbrella term) | Isolated forms are rare, except types A3 and D, which are common5 |
| Cenani-Lenz syndrome | <1 / 1 000 000 prevalence (Worldwide); about 30 cases described ORPHA:325811 | No population figure found |
| Crossed polysyndactyly | <1 / 1 000 000 prevalence (Worldwide); about 12 cases described ORPHA:293511 | No population figure found |
| Ectrodactyly (SHFM) | 1-9 / 100 000 birth prevalence, mean 5.4 per 100,000 (Europe); 1-9 / 100 000 prevalence (Europe) ORPHA:244011 | Central ray deficiency: 41 in 753,342 births, about 0.5 per 10,000 (Finland), consistent with Orphanet6 |
| Fibular hemimelia | 1-9 / 100 000 birth prevalence, mean 1.1033 per 100,000 (Worldwide); 1-9 / 100 000 prevalence, mean 1.1033 per 100,000 (Worldwide) ORPHA:9332311 | All lower-limb deficiencies: 2.8 per 10,000 births (Finland, 266 cases)8 |
| Holt-Oram syndrome | 1-9 / 1 000 000 birth prevalence, mean 0.7 per 100,000 (Europe) ORPHA:39211 | No population figure found |
| Microgastria–limb reduction | <1 / 1 000 000 prevalence (Worldwide); about 16 cases described ORPHA:253811 | No population figure found |
| Phocomelia | Prevalence unknown ORPHA:287911 | All forms of phocomelia: 0.74 per 100,000 births (Finland, 7 cases, 1993-2008)2 |
| Poland syndrome | 1-9 / 100 000 birth prevalence, mean 3.1 per 100,000 (Canada); 1-9 / 100 000 prevalence (Canada) ORPHA:291111 | No population figure found |
| Polydactyly | No epidemiological data published ORPHA:291311 | 8.4 per 10,000 births (northern Netherlands, 1981-2010)3; the most common upper-limb anomaly in Korea, where all upper-limb anomalies total 23.5 per 10,000 live births10 |
| Radial aplasia | 1-9 / 100 000 birth prevalence, mean 2.5 per 100,000 (Worldwide); 1-9 / 100 000 prevalence, mean 2.5 per 100,000 (Worldwide) ORPHA:9332111 | Radial ray deficiency, all forms: 1.83 per 10,000 births, 13% of them isolated (Finland)7; the isolated share matches Orphanet's figure |
| Roberts syndrome | Prevalence unknown; about 150 cases described ORPHA:310311 | Prevalence unknown; part of the ESCO2 spectrum12 |
| Symbrachydactyly | Not an Orphanet entity as such; ORPHA:1570 covers only the rare form affecting hands and feet (2 cases described) | Undergrowth category, mainly symbrachydactyly: 91 in 753,342 births, about 1.2 per 10,000 (Finland)6 |
| Syndactyly | No epidemiological data published ORPHA:9345811 | 4.7 per 10,000 births (northern Netherlands, 1981-2010; non-syndromic cases fell from 5.2 to 1.1 between 1992 and 2010)3; 5.63 per 10,000 (China, 2007-2019, 13,611 cases)4 |
| Tetra-amelia | <1 / 1 000 000 prevalence (Worldwide); about 5 families described ORPHA:330111 | No population figure found |
| Thrombocytopenia-absent radius (TAR) | 1-9 / 1 000 000 birth prevalence, mean 0.5 per 100,000 (Europe) ORPHA:332011 | No population figure found |
| Tibial aplasia–ectrodactyly | 1-9 / 1 000 000 prevalence, mean 0.1 per 100,000 (Europe) ORPHA:332911 | No population figure found |
| Tibial hemimelia | 1-9 / 1 000 000 birth prevalence, mean 0.1 per 100,000 (Europe); 1-9 / 1 000 000 prevalence, mean 0.1 per 100,000 (Europe) ORPHA:9332211 | All lower-limb deficiencies: 2.8 per 10,000 births (Finland)8 |
| Ulnar hemimelia | 1-9 / 1 000 000 prevalence (Europe) ORPHA:9332011 | Ulnar ray deficiency: 33 in 753,342 births, about 0.44 per 10,000, i.e. 4 per 100,000 (Finland)6, above Orphanet's not-yet-validated class |
How to read these figures: they describe births, not the number of people living with a condition; ranges are Orphanet's prevalence classes; the named conditions do not add up to the total for limb reduction defects, because most limb differences are isolated deficiencies without a syndrome name. Rates also differ between populations and registries. None of this is medical advice.
Sources
- Bermejo-Sánchez E, Cuevas L, Amar E, et al. Amelia: a multi-center descriptive epidemiologic study in a large dataset from the International Clearinghouse for Birth Defects Surveillance and Research, and overview of the literature. Am J Med Genet C Semin Med Genet. 2011;157C(4):288-304. doi.org/10.1002/ajmg.c.30319
- Pakkasjärvi N, Syvänen J, Wiro M, Koskimies-Virta E. Amelia and phocomelia in Finland: characteristics and prevalences in a nationwide population-based study. Birth Defects Res. 2022;114(20):1427-1433. doi.org/10.1002/bdr2.2123
- Vasluian E, van der Sluis CK, van Essen AJ, et al. Birth prevalence for congenital limb defects in the northern Netherlands: a 30-year population-based study. BMC Musculoskelet Disord. 2013;14:323. doi.org/10.1186/1471-2474-14-323
- Chen ZY, Li WY, Xu WL, et al. The changing epidemiology of syndactyly in Chinese newborns: a nationwide surveillance-based study. BMC Pregnancy Childbirth. 2023;23:334. doi.org/10.1186/s12884-023-05660-z
- Temtamy SA, Aglan MS. Brachydactyly. Orphanet J Rare Dis. 2008;3:15. doi.org/10.1186/1750-1172-3-15
- Koskimies E, Lindfors N, Gissler M, Peltonen J, Nietosvaara Y. Congenital upper limb deficiencies and associated malformations in Finland: a population-based study. J Hand Surg Am. 2011;36(6):1058-1065. doi.org/10.1016/j.jhsa.2011.03.015
- Pakkasjärvi N, Koskimies E, Ritvanen A, Nietosvaara Y, Mäkitie O. Characteristics and associated anomalies in radial ray deficiencies in Finland: a population-based study. Am J Med Genet A. 2013;161A(2):261-267. doi.org/10.1002/ajmg.a.35707
- Syvänen J, Nietosvaara Y, Ritvanen A, Koskimies E, Kauko T, Helenius I. High risk for major nonlimb anomalies associated with lower-limb deficiency: a population-based study. J Bone Joint Surg Am. 2014;96(22):1898-1904. doi.org/10.2106/JBJS.N.00155
- Klungsøyr K, Nordtveit TI, Kaastad TS, et al. Epidemiology of limb reduction defects as registered in the Medical Birth Registry of Norway, 1970-2016: population based study. PLoS One. 2019;14(7):e0219930. Cites the EUROCAT figure for Europe 2003-2012 (Morris et al., 2018). doi.org/10.1371/journal.pone.0219930
- Shin YH, Baek GH, Kim YJ, Kim MJ, Kim JK. Epidemiology of congenital upper limb anomalies in Korea: a nationwide population-based study. PLoS One. 2021;16(3):e0248105. doi.org/10.1371/journal.pone.0248105
- Orphanet. Orphadata, epidemiological data (product 9), release of 23 June 2026. Licence CC BY 4.0. www.orphadata.com/epidemiology/
- Gordillo M, Vega H, Jabs EW. ESCO2 Spectrum Disorder. In: GeneReviews. University of Washington, Seattle. www.ncbi.nlm.nih.gov/books/NBK1153/