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Bifid distal phalanx of the thumb

MedGen UID:
Concept ID:
Congenital Abnormality; Finding
Synonym: Bifid thumb distal phalanx
HPO: HP:0009611


Partial duplication of the distal phalanx of the thumb. Depending on the severity, the appearance on x-ray can vary from a notched phalanx (the duplicated bone is almost completely fused with the phalanx) to a partially fused appearance of the two bones. [from HPO]

Term Hierarchy

Conditions with this feature

Acrocallosal syndrome
MedGen UID:
Concept ID:
Disease or Syndrome
Classic Joubert syndrome (JS) is characterized by three primary findings: A distinctive cerebellar and brain stem malformation called the molar tooth sign (MTS). Hypotonia. Developmental delays. Often these findings are accompanied by episodic tachypnea or apnea and/or atypical eye movements. In general, the breathing abnormalities improve with age, truncal ataxia develops over time, and acquisition of gross motor milestones is delayed. Cognitive abilities are variable, ranging from severe intellectual disability to normal. Additional findings can include retinal dystrophy, renal disease, ocular colobomas, occipital encephalocele, hepatic fibrosis, polydactyly, oral hamartomas, and endocrine abnormalities. Both intra- and interfamilial variation are seen.
Rhizomelic syndrome, Urbach type
MedGen UID:
Concept ID:
Disease or Syndrome
Rhizomelic syndrome, Urbach type is a rare primary bone dysplasia characterized by upper limbs rhizomelia and other skeletal anomalies (e.g. short stature, dislocated hips, digitalization of the thumb with bifid distal phalanx), craniofacial features (e.g. microcephaly, large anterior fontanelle, fine and sparse scalp hair, depressed nasal bridge, high arched palate, micrognathia, short neck), congenital heart defects (e.g. pulmonary stenosis), delayed psychomotor development and mild flexion contractures of elbows. Radiologic evaluation may reveal flared epiphyses, platyspondyly and/or digital anomalies.
Nephrosis-deafness-urinary tract-digital malformations syndrome
MedGen UID:
Concept ID:
Disease or Syndrome
A rare, genetic, multiple congenital anomalies syndrome characterized by urinary tract anomalies, nephrosis, conductive deafness, and digital malformations, including short and bifid distal phalanges of thumbs and big toes. There have been no further descriptions in the literature since 1962.
Coloboma of macula-brachydactyly type B syndrome
MedGen UID:
Concept ID:
Disease or Syndrome
A malformation syndrome with the combination of bilateral coloboma of macula, horizontal pendular nystagmus, severe visual loss and brachydactyly type B. The hand and feet defects comprise shortening of the middle and terminal phalanges of the second to fifth digits, hypoplastic or absent nails, broad or bifid thumbs and halluces, syndactyly and flexion deformities of the joints of some digits. Inherited in a dominant manner.
Acropectorovertebral dysplasia
MedGen UID:
Concept ID:
Disease or Syndrome
Acropectorovertebral dysgenesis, or F syndrome, is an autosomal dominant skeletal dysplasia characterized by carpal and tarsal synostoses, syndactyly between the first and second fingers, hypodactyly and polydactyly of feet, and abnormalities of the sternum and spine (summary by Thiele et al., 2004).
Desbuquois dysplasia 1
MedGen UID:
Concept ID:
Disease or Syndrome
Desbuquois dysplasia (DBQD) is an autosomal recessive chondrodysplasia belonging to the multiple dislocation group and characterized by severe prenatal and postnatal growth retardation (stature less than -5 SD), joint laxity, short extremities, and progressive scoliosis. The main radiologic features are short long bones with metaphyseal splay, a 'Swedish key' appearance of the proximal femur (exaggerated trochanter), and advanced carpal and tarsal bone age with a delta phalanx (summary by Huber et al., 2009). Desbuquois dysplasia is clinically and radiographically heterogeneous, and had been classified into 2 types based on the presence (type 1) or absence (type 2) of characteristic hand anomalies, including an extra ossification center distal to the second metacarpal, delta phalanx, bifid distal thumb phalanx, and dislocation of the interphalangeal joints (Faivre et al., 2004). However, patients with and without these additional hand anomalies have been reported to have mutations in the same gene (see, e.g., CANT1); thus, these features are not distinctive criteria to predict the molecular basis of DBQD (Furuichi et al., 2011). In addition, Kim et al. (2010) described another milder variant of DBQD with almost normal outwardly appearing hands, but significant radiographic changes, including short metacarpals, elongated phalanges, and remarkably advanced carpal bone age. However, there is no accessory ossification center distal to the second metacarpal, and patients do not have thumb anomalies. Similar changes occur in the feet. These patients also tend to develop precocious osteoarthritis of the hand and spine with age. This phenotype is sometimes referred to as the 'Kim variant' of DBQD (Furuichi et al., 2011). Genetic Heterogeneity of Desbuquois Dysplasia DBQD2 (615777) is caused by mutation in the XYLT1 gene (608124) on chromosome 16p12. Two unrelated patients with immunodeficiency-23 (IMD23; 615816), due to mutation in the PGM3 gene (172100), were reported to have skeletal features reminiscent of DBQD.
Gonadal dysgenesis, dysmorphic facies, retinal dystrophy, and myopathy
MedGen UID:
Concept ID:
Disease or Syndrome
Myoectodermal gonadal dysgenesis syndrome (MEGD) is characterized by 46,XY complete or partial gonadal dysgenesis, or 46,XX gonadal dysgenesis, in association with extragonadal anomalies, including low birth weight, typical facies, rod and cone dystrophy, sensorineural hearing loss, omphalocele, anal atresia, renal agenesis, skeletal abnormalities, dry and scaly skin, severe myopathy, and neuromotor delay. Dysmorphic facial features along with muscular habitus are the hallmarks of the syndrome. Abnormal hair patterning with frontal upsweep and additional whorls, eyebrow abnormalities comprising broad, arched, and sparse or thick eyebrows, underdeveloped alae nasi, smooth philtrum, and low-set ears with overfolded helices facilitate a gestalt diagnosis. (Guran et al., 2019; Altunoglu et al., 2022).

Recent clinical studies


Lapegue F, Tiercelin M, Siala M, Andre A, Rongieres M, Franchet C, Brouchet-Gomez A, Nougarolis F, Ricard C, Bachour R, Basselerie H, Chiavassa H, Faruch-Bilfeld M, Sans N
Eur Radiol 2020 Dec;30(12):6653-6662. Epub 2020 Jul 4 doi: 10.1007/s00330-020-07048-5. PMID: 32623504
Baek GH, Gong HS, Chung MS, Oh JH, Lee YH, Lee SK
J Bone Joint Surg Am 2008 Mar;90 Suppl 2 Pt 1:74-86. doi: 10.2106/JBJS.G.01104. PMID: 18310688


Inoue S, Ishii A, Shirotani G, Tsutsumi M, Ohta E, Nakamura M, Mori T, Inoue T, Nishimura G, Ogawa A, Hirose S
Pediatr Int 2014 Aug;56(4):e26-9. doi: 10.1111/ped.12383. PMID: 25252066

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