Ulnar hypoplasia/aplasia is a longitudinal deficiency at the posterior axis of the upper limb wherein the ulna is partially or completely absent. If the deficiency is incomplete, the ulnar remnant may vary in length and contour. The elbow joint may be in extension or in acute flexion. ¹ , ² At the shoulder girdle, one may observe considerable muscular atrophy, ligamentous relaxation, and a deep web in the axilla. ¹ , ² This condition may accompany hypoplasia of the radius. O′Rahilly proposed an anatomical classification of limb anomalies and expanded the concept of intercalary deficiencies. ² Additionally, oligodactyly is a common presentation and the number of absent digits varies greatly. Depending upon the severity of longitudinal deficiency at the ulnar or radial ray in the zeugopod, the postaxial or preaxial fingers could be omitted, respectively. However, ulnar deficiency with the absence of preaxial digits is extremely rare and has not been much appreciated. ³ In this communication, we present a male child, a product of a consanguineous marriage, with a rare association of ulnar hypoplasia and the absence of two preaxial fingers, the remaining digits depicting postaxial/posterior identities.

The subject, a 12-year-old school-going boy, originates from a rural area of Southern Punjab, Pakistan. His parents were first cousins (inbreeding coefficient, F = 0.0625), and he had four normal siblings (3 brothers, 1 sister). The maternal and paternal ages were 28 and 33 years, respectively, at the time of his birth. The pregnancy had been uneventful and the birth was at home, in the presence of a traditional birth attendant. The study was approved by the institutional review committee and all the information was obtained according to the Helsinki II declaration. The initial ascertainment and detailed clinical examinations were carried out in several visits during 2009-2010.

The subject had normal developmental landmarks, dentition, and intelligence quotient (IQ). He was observed to have an isolated limb anomaly. Upon physical examination, he had a standing height of 146 cm, sitting height 71 cm, arm span 130 cm, head circumference 53 cm, neck circumference 29 cm, and chest 68 cm. There was no family history of any limb or other anomaly.

Clinical examination showed a short left arm Figure 1A. The upper arm was thin and weak, and the middle and forearm were reduced in size. The elbow demonstrated limited flexion and extension Figure 1A,B. The middle arm was flat and depicted restricted supination. The palm was narrow with a few flexion creases Figure 1C. The ′hand′ harbored only three functional fingers identified as third, fourth, and fifth, each comprising two flexion creases at the interphalangeal joints. The thumb and index finger were completely omitted. The posterior finger, that is, the fifth digit, was weak and showed volar inclination Figure 1A,C. Figure 1

Phenotype in subject; a-e: Photographs and radiograph of upper limbs

Ulnar longitudinal deficiencies are very rare and their prevalence has been estimated to be 1-2 in 100,000 live births. ⁴ , ⁵ Several different classification systems have been proposed for ulnar ray deficiency (reviewed by Al-Qattan, 2010). ³ O′Rahilly suggested a classification of congenital limb anomalies that was based on anatomical differences.- ¹ , ² Ogden et al. provided a classification based upon the severity of the ulnar deformity. ⁶ Bayne considered the degree of ulnar deficiency and also the radiohumeral synostosis. ⁷ Ogino and Kato provided a system which also integrated into the classification the deficiency of fingers at the ulnar side. ⁸ Cole and Manske added thumb/first web deformity to the ulnar ray deficiency. ⁹ Hence, according to the O′Rahilly scheme, the present anomaly can be classified as ulnar-preaxial carpal-phalangeal meromelia.- ¹ , ² According to the Bayne system, the presentation in our subject is close to type II (i.e., partial aplasia of the ulna). On the other hand, our case is difficult to characterize according to the Ogino-Kato scheme because here the radial digits are omitted and the remaining fingers maintain posterior/ulnar identities. According to the Cole-Manske system, which also considers the absent thumb, the present case is closer to type D. Proximally, when the ulna is absent, the radius can be unstable in its articulation with the humerus and shows proximal dislocation. This situation was appreciated by Kummel who provided a classification of elbow deformity. ¹⁰ Accordingly, our case can be classified as type III (i.e., radial head dislocation).

The clinical presentation in our subject is best classified as ulnar aplasia, dysplastic radius, and preaxial oligodactyly. There was no evidence of radioulnar synostosis or fusion at the angle joint, that is, humeroradial juxtaposition. However, severe flexion contracture of the elbow and radial head dislocation were witnessed. The radiocarpal joint was stable. We also considered differential diagnosis and reported cases with the Schinzel syndrome, Marles-Chudley syndrome, Weyer′s ulnar ray/oligodactyly syndrome [Online Mendelian Inheritance in Man (OMIM): 602418], limb/pelvis-hypoplasia/aplasia syndrome (OMIM: 276820), ulnar-mammary syndrome (OMIM:181450), Fuhrmann syndrome (OMIM: 228930), and Cornelia de Lange syndrome (OMIM: 122470). ¹¹ However, all these syndromic anomalies can be safely excluded as they show associations of orofacial, cardiac, and/or ectodermal organs.

The studies on hereditary and congenital limb deficiencies are relatively scarce in Pakistan. Only a few reports depicting digit deficiencies have been published. ¹² , ¹³ , ¹⁴ There is no previous study on longitudinal limb defects.

Congenital limb and/or finger loss is a potentially devastating event which imparts profound physical, psychological, and vocational consequences on the subject as well as his/her family. ¹⁵ Despite the potential adverse impact of partial loss or deficiency on daily function and the quality of life, management is not easy and no immediate help is available. Prosthetic and cosmetic measures not only require long-term follow-up and skilled surgical procedures but are also known to offer limited rescue. The etiology of such defects is not fully understood mainly due to the rarity of reported subjects and familial cases, poor understanding of inheritance patterns, and lack of molecular and genetic data. Further studies are warranted on the pathophysiology of longitudinal limb defects to propose better therapeutic and surgical options for the subjects.

Author contributions

MA ascertained the case and helped in data collection. SM analyzed the data and drafted the manuscript. Both authors read and approved the content of the manuscript.

The authors highly appreciate the participation of the subject and his family in this study and are indebted to Drs. Van Heest AE, Ferguson JH, Ogino T, Evans J, Koskimies E, and Goldfarb CA for their expert help in the diagnosis.