Study of hereditary disorders in population of Dir Upper, KPK

Abstract

Hereditary/congenital anomalies are a significant cause of infant morbidity and mortality throughout the world. The incidence of hereditary anomalies differs from region to region as well as in different populations and ethnic groups. These anomalies not only affect the life of the index subject, but also cause a great socioeconomic burden upon the family and the society. The present genetic epidemiological study was carried out to analyze the distribution of hereditary anomalies along with their bio-demographic factors prevalent in the population of Dir Upper district of Khyber Pakhtunkhwa. A total of 176 index subjects with certain types of hereditary disorders were recruited, and they belonged to 149 independent families. Data were collected on clinical detail, familial attributes and socio-demographic variables. Among the 176 index subjects, male-to- female ratio was 3.8:1. Most of the subjects (n=70) were in the age range of 1-9 years. The sporadic cases were 64.2% and familial were 35.8%. An estimated 88.10% of the subjects belonged to rural area and 11.90% were from urban communities. The hereditary malformations were classified into nine major categories, of those limb defects were more common 48%, followed by mental retardation 12%, cleft lip/palate 10%, visual defects 10%, deaf/mute cases 6%, musculo-skeletal defects 5%, while neuro-muscular, ectodermal defects and other minor anomalies were 4%, 3% and 2%, respectively. In sporadic cases, the parity of most of the subjects were of 1 st and 2 nd (n=48). In the familial cases the disease segregated mostly up to one generation (42.9%) or two generations (47.62%). The limb anomalies were further classified into 12 subgroups, most common of which was polydactyly (n=22), followed by clubfoot (n=16), syndactyly (n=13), clinodactyly (n=6), camptodactyly and amputations (n=5 each). Other malformations were: symbrachydactyly (n=3), brachydactyly, thumb anomaly (n=2 each), arthrogryposes, macrodactyly (n=1 each), and others (n=8). In the index case, a total of 132 limbs were affected; both upper (n=56) and lower (n=76) were involved in certain anomalies. The ratios of affected right to left arms and legs were 1:1.33 and 1.1:1, respectively. The ratio for unilateral to bilateral was 1:1.2, and symmetrical to asymmetrical was 1:2.36. In prenatal marriage types, the consanguineous marriages were 39.8%. A highly significant (p<0.0001) difference was observed in parental ages in case of limb defects, whereas for mental retardation, neuro-muscular defects and deaf/mute cases, the parental ages were also significantly different (p<0.05). In 26 index subjects, there were 27 certain other associated anomalies, while in 51 index cases there were 59 other anomalies in other family members. The results of this study matched with the previous findings and the deviation of results from previous studies can be explained due to the over representation of male subjects. Studies to elucidate the spectrum of genetic disorders are important to establish baseline rates, document any possible increase or decrease over time, and to identify clues to the etiology. The results of the present study would be useful to understand the spectrum of genetic disorders in the population and could be helpful in suggesting the preventive measures for genetic disorders.