The Prevalence and Comparison of Bent Little Finger and Hitchhiker’s Thumb in South-South Nigeria

Background: One of the most important principles that govern life is inheritance of genes. There are over 200 traits that are transmitted from generation to generation in humans. When one of the two parents expresses the trait, there is 25-50% likelihood of passing it to any of the children; but if both parents have it, the probability doubles (50-100%). There are three main types of bent little finger, which are Camptodactyly, Clinodactyly and Kirner's deformity. The aim of this research is to find out and document data on the prevalence and comparison of dominant bent little finger and recessive Hitchhiker’s thumb in SouthSouth Nigeria. Methods: A random sample of three hundred and ten (male 119 and female 191) subject with age ranging from 17 to 49 years were observed for the presence or absence of bent little finger and Hitchhiker’s thumb. Results: Prevalence of Bent Little Finger (BLT) in South-South Nigeria is 7.1% (male 1.6% and female 5.5%), while the prevalence of Hitchhiker’s Thumb (HT) is 32.3% (male 15.5% and female 16.8%). Females tend to have more finger anomalies than their male counterparts in South-South Nigeria. Conclusion: females are conscious of their beauty and as such go extra miles to fix artificial such as nails, hair on the head, eye lashes, eye balls etc. On the contrary they tend to have more finger anomalies than their male counterparts in South-South Nigeria. Key word: Deformities Hitchhiker Gene Recessive and Dominant Trait INTRODUCTION hand clasping [2]. When one of the two parents expresses One of the most important principles that govern the children; but if both parents have it, the probability life is inheritance of genes. There are over 200 traits doubles (50-100%) [3]. that are transmitted from generation to generation in The malformation of the little finger was first humans. These interesting aspects of human genetics described by Kirner [4]. It consists of radial bowing of the are known as hereditary traits. These hereditary traits terminal phalanx. The tip of the little finger points towards include the dominant and recessive traits in the thenar eminence. This malformation is usually bilateral humans. Most of the genes are transmitted in the [4]. A dominant gene causes the last joint of the little Mendelian pattern and a few are transmitted through finger to bend inward toward the fourth finger [5]. the non-Mendelian pattern that includes: co-dominance, There are three main types of bent little finger, which are sex-linked genes and polygenes. The physical traits Camptodactyly, Clinodactyly and Kirner's deformity. are those that are expressed and what makes every Camptodactyly involves the metacarpo-phalangeal individual an 'individual' [1]. Traits inherited in an (hand/finger junction) and proximal inter-phalangeal autosomal dominant pattern include free earlobe, early joints. Clinodactyly involves the proximal inter-phalangeal onset myopia, bent little finger, Achoo syndrome, tongue joint only and Kirner's affects the end joint, the distal rolling, eye colour, mid-digital hair, facial dimples and inter-phalangeal joint. the trait, there is 25-50% likelihood of passing it to any of Europ. J. Appl. Sci., 4 (4): 157-159, 2012 158 Whilst these conditions are worrying for the parents, RESULT most children are unaffected both functionally and to begin with, emotionally by the deformities. The exception The result shows that the Prevalence of Bent Little is usually a teenage girl, who becomes very conscious Finger (BLT) in South-South Nigeria is 7.1% (male 1.6% that the finger is not straight and therefore cosmetically and female 5.5%), while the prevalence of Hitchhiker’s it is a 'disaster'. They considered the deformity of the Thumb (HT) is 32.3% (male 15.5% and female 16.8%). little finger as congenital with lack of the radiological signs before epiphyseal ossification at about the age of DISCUSSION 2 years [6]. Camptodactyly is defined as a permanent flexion The result shows that the prevalence of Bent Little contracture of one or both fifth fingers at the proximal Finger (BLT) in south-south Nigeria is 7.1%, it was interphalangeal joints. Additional fingers might be discovered that 1.6% of the males had BLT and 5.5% for affected, but the little finger is always involved. female, Table 1. This result is slightly higher than a If all fingers of both hands show contractures some previous research carried out by Armand et al., [5], authors call the anomaly streblodactyly [7-10]. where the total recorded prevalence was less than 1%. Camptodactyly and streblodactyly are used Our result also was different from the result obtained in a interchangeably, while camptodactyly is the more Japanese village, Saito [16] found a frequency of 0.46% in common term [11-13]. males and 0.63% in females, but agreed from the Hitchhiker’s Thumb is a trait actually known as perspective that the prevalence of BLT is higher in “Distal Hyperextensibility of the Thumb”, but that females than in males and in an estimated incidence is too hard to remember! This trait is distinguished by of 1 in 410 where female was higher than male [17]. the ability to bend the distal joint of the thumb back The prevalence of BLT according to our research and few as far as possible. Some people can bend their other researches in the world shows a low prevalence, thumb back as far as a 90 degree angle. It is believed while females are on the increase when compared to their this trait is caused by a recessive gene (h), meaning male counterparts. 2 copies are required to display this characteristic The prevalence of Hitchhiker’s Thumb (HT) has not [14]. Population diversity provides a unique really been given due attention. However in our research opportunity to study the morphogenetic variation the prevalence of HT is 32.3% (male 15.5% and female among the endogamous populations living in 16.8%) Table 2. Which is higher than that of the BLT 7.1% different geographical and ecological conditions [15]. and 32.3% respectively but the females still maintained a The aim of this research is to find out and document higher increase Table 3. data on the prevalence and comparison of dominant bent little finger and recessive Hitchhiker’s thumb in Southern Nigeria. MATERIALS AND METHODS A random sample of three hundred and ten (male 119 and female 191) subject with age ranging from 17 to 49 years where collected in the May/June 2011. Subjects used where Nigerians dwelling in Bayelsa, South-South of the country, both parents of subjects were also from Nigeria. Subject with dislocation or fractured phalanges where excluded from the research. Inform consent was granted by individual subject. They were observed for the presence or absence of bent little finger and Hitchhiker’s thumb. Data was analyzed by the use of simple percentage. Table 1: Prevalence of Bent Little Finger (BLT) Sex Presence of BLF (%) Absence of BLF (%) Total (%) Male 5 (1.6) 305 (98.4) 310 (100) Female 17 (5.5) 293 (94.5) 310 (100) Table 2: Prevalence of Hitchhiker’s Thumb (HT) Sex Presence of HT (%) Absence of HT (%) Total (%) Male 48 (15.5) 262 (84.5) 310 (100) Female 52 (16.8) 258 (83.2) 310 (100) Table 3: Comparison of the Presence of BLT and HT