ABSTRACT
Familial 22q11.2 deletions have been reported as a 6%-28% of the total affected cases of 22q11.2 microdeletion syndrome (del22q11.2). Different deletion genotypes have been described for this disorder, with a predominant 3 Mb deletion present in 90% of the cases, a less common 1.5-2 Mb deletion in 8%, and atypical smaller deletions in 2%. We have studied 15 cases of del22q11.2 from 6 families (two of them three-generation families) that were previously diagnosed through FISH. We have sized the deleted region by allele genotyping of 12-16 polymorphic markers in all cases, and we have found three families affected with the 1.5-2 Mb deletion, two affected with the 3 Mb deletion, and one in which the deletion size could not be determined. This predominance of the smaller 1.5-2 Mb deletions in our familial cases differs from the minor frequency observed in sporadic cases of del22q11.2. This finding suggests that small deletions are more linked to familial inheritance than large ones, possibly due to psychosocial or biological factors associated with differences in the phenotype. Deletion sizing on routine diagnosis may help characterizing the inheritability of 22q11.2 microdeletion syndrome.
Subject(s)
Chromosome Deletion , Chromosomes, Human, Pair 22/genetics , Abnormalities, Multiple/genetics , Abnormalities, Multiple/pathology , Adolescent , Adult , Aged , Child , Face/abnormalities , Family Health , Female , Humans , In Situ Hybridization, Fluorescence , Infant, Newborn , Intellectual Disability/pathology , Male , Microsatellite Repeats , Palate/abnormalities , Syndrome , Tetralogy of Fallot/pathologyABSTRACT
Infantile systemic hyalinosis (ISH) is a presumed autosomal recessive connective tissue condition. Symptoms usually begin at birth or shortly thereafter, and are characterized by pain when handled, painful and swollen joints and, later on, dermal anomalies, diarrhea, failure to thrive and recurrent infections, which usually lead to death around the age of 2. The skin has generally diminished elasticity with small pearly papules appearing on neck, ears, coccygeal region, and face. We present two unrelated patients with ISH, with specific focus on clinical and pathologic studies. In the first patient the diagnosis was made several years after she died, in a retrospective study of her clinical file. On ultrastructural examination both patients showed an accumulation of fibrillogranular material in the extracellular matrix with long-spacing collagen of 90 nm. The first child died at the age of 1(1/2) years and the second at 3 years.
