Seckel's Dwarfism: Analysis of Chromosome Breakage and Sister Chromatid Exchanges

Abstract

In the monograph by Seckel,1the phenotype of bird-headed dwarfs has been delineated in detail. Main features include proportionate dwarfism with low birth weight, microcephaly with simplified gross cerebral structure, mental retardation, typical narrow face with micrognathia, large eyes, and beak-like nose. Numerous skeletal and genitourinary anomalies have been described. The syndrome is inherited in an autosomal recessive manner, with an incidence of about 1:10,000 live births and equal distribution between males and females. This report describes two Japanese brothers, with particular emphasis on their chromosomal constitution (Figure). Report of Cases.—Case1.—This boy was 8 years old at the time of examination. He was the result of a normal pregnancy and delivered at term in the breech position. The mother was 31 years old and the father was 34 years old at the time of his birth. Birth weight was 1,040 g. At 8 years of age,