Characterization of a rare short arm heteromorphism of chromosome 22 in a girl with down-syndrome like facies.

Chromosomal heteromorphisms are described as interindividual variation of chromosomes without phenotypic consequence. Chromosomal polymorphisms detected include most regions of heterochromatin of chromosomes 1, 9, 16 and Y and the short arms of all acrocentric chromosomes. Here, we report a girl with Down‑syndrome such as facies and tremendously enlarged short arm of a chromosome 22. Fluorescence in situ hybridization (FISH) with a probe specific for all acrocentric short arms revealed that the enlargement p arms of the chromosome 22 in question contained exclusively heterochromatic material derived from an acrocentric short arm. Parental studies identified a maternal origin of this heteromorphism. Cryptic trisomy 21 of the Down‑syndrome critical region was excluded by a corresponding FISH‑probe. Here, we report, to the best of our knowledge, largest ever seen chromosome 22 short arm, being ~×1.5 larger than the normal long arm.

Renal amyloidosis due to familial Mediterranean fever misdiagnosed.

Familial Mediterranean fever (FMF, MIM 249100) is an autosomal recessive disease affecting mainly patients of the Mediterranean basin. It is an autoinflammatory periodic disorder characterized by recurrent episodes of fever and abdominal pain, synovitis, and pleuritis. The major complication of FMF is the development of renal AA amyloidosis. Treatment with colchicine prevents the occurrence of recurrent seizures and renal amyloidosis. The disease is caused by mutations in the MEFV gene. We report here the cases of two unrelated patients, who have been late diagnosed with FMF complicated by renal amyloidosis. We focus on the importance of early diagnosis of FMF, both to start rapidly treatment with colchicine and avoid renal amyloidosis, and to provide genetic counseling to families.