CONGENITAL-ABNORMALITIES ASSOCIATED WITH LIMB DEFICIENCY DEFECTS - A POPULATION STUDY BASED ON CASES FROM THE HUNGARIAN CONGENITAL-MALFORMATION REGISTRY (1975-1984)

Limb deficiency defects (LD) occurring among 1,575,904 births in Hunga ry during 1975-1984 were reviewed. The overall birth prevalence of LD was 1 in 1,816. This paper discusses the nature and distribution of th e limb and other defects in the 275 (32%) children who had structural malformations in other systems. Two main forms of classification were used: morphologic and causal. Additional malformations were most commo nly seen in infants with amelia, rudimentary limb (RL), radial/tibial (RT), intercalary or central axis (CA) LD and rarely in those with ter minal transverse (TT) or ulnar/fibular (UF) defects. Upper limbs (81%) were involved significantly more often than lower limbs (42%) and the re were more right-sided defects (83% vs. 71%) due to an excess of rig ht arm involvement especially with radial ray and split hand anomalies . Single limb involvement was relatively common with amelia (88%), UF (82%), RT (50%), and TT (50%) defects. With other LD, multimelic invol vement was more characteristic. This was usually symmetric with interc alary and RL defects but asymmetric with CA anomalies and digital defi ciencies (DD). From a causal perspective, 17% of cases had genetic dis orders, 52% had recognized associations, anomalies, sequences, environ mental causes or patterns of unknown origin, and 31% had unknown patte rns of malformations. The commonest entities were amnion disruption se quence (16% of cases) and VACTERL association (8%). Both of these diso rders showed unusual temporal distribution. As anticipated, patterns o f malformations differed with the type of LD. Amelia and digital amput ations were often seen with body wall defects, atypical anencephaly or encephalocele, and cleft lip reflecting amnion disruption. Rudimentar y limb was seen with anencephaly, omphalocele, renal agenesis, aberran t genitalia, and imperforate anus, reflecting defects of blastogenesis including the cloacal exstrophy and caudal regression sequences and S chisis association. Radial/tibial defects were associated with differe nt patterns depending on whether the limb defects were unilateral or b ilateral. Unilateral defects occurred with anomalies suggesting VACTER L association or the facio-auriculo-vertebral anomaly, while bilateral defects occurred more often in genetic or potentially genetic disorde rs including VACTERL with hydrocephalus. Central axis defects showed t hree main patterns of association: one reflecting the ectrodactyly-ect odermal dysplasia-clefting syndrome; one with tongue anomalies represe nting a variant of ore-mandibular-limb (Hanhart) anomaly, and the last with hydronephrosis indicating a group of ''acrorenal'' syndromes. St rong associations with other anomalies were not seen in the groups wit h TT, UF, or intercalary defects.