[Mechanism of a genetically conditioned failure to thrive shown in a patient with ring chromosome 18]

The influence of genetic factors on growth is only partially understood. The assumed regulatory mechanism is an interplay of multiple genes, which are localized on various chromosomes. Numerical and unbalanced structural chromosome anomalies cause abundance or lack of genes and gene products. As a consequence the subtle, in their complexity hardly fully conceivable regulatory mechanisms for metabolism and growth of the single cells appear to be disturbed. This kind of model is supported by the occurrence of growth failure in most numerical and structural chromosome anomalies. Further evidence is the variability of the phenotype in cases of ringchromosome 18, which depends on the localization and degree of loss of chromosome material preceding ring formation: depending on the participation of one or several growth-regulating genes normal or impaired growth follows. Consequently we find some normally thrived proponents within the group of predominantly mal grown people with ringchromosome 18. Besides growth the phenotypical variability is concerned with a whole lot of body-functions and systems and virtually every case reported in the literature shows individual signs. This is also true for the patient reported in this paper, in whom we additionally describe the following hitherto not mentioned signs: rudimentary pair of first ribs, apical pulmonary hernias, submammilary dermal groove, hemangioma, meatal stenosis of the urethra, unilateral kidney aplasia, 6 lumber vertebral bodies, umbilical-, abdominal- and inguinal hernias.