A balanced reciprocal translocation in a case of hypomelanosis of Ito with confirmation of mosaicism using buccal cell interphase FISH

Abstract

We report on a boy who was born to a nonconsanguineous Caucasian couple at full term with a birth weight of 3.9 kg. There was hypertension during pregnancy but no other complications. There were no perinatal problems, and he fed well in the first weeks of life. He has an older sister who is well and there was no other significant family history. At 8 months of age, he developed generalized seizures. He subsequently showed significant global neurodevelopmental delay, functioning around 9 months in contrast to a chronological age of 43 months. EEG, brain CT, and MRI scans and metabolic screen were all normal. Peripheral blood lymphocyte chromosome analysis, subtelomeric FISH analysis and molecular tests for Angelman syndrome and fragile X were also normal. He presented to the clinical genetics department as a 6.5-year-old boy. At that time his height and weight were both between the 75-90th centile for his age and his head circumference was 56.2 (>97th centile for age). Depigmented streaks were identified over his back, buttock, and left flank (Fig. 1). Some of these clearly followed Blaschko's lines. There were no specific facial dysmorphic features. A diagnosis of hypomelanosis of Ito was made and a single 3-mm punch biopsy of skin was taken from the upper outer left arm from a region showing no evidence of depigmentation. Four out of 50 (8%) metaphases

Pigmentary mosaicism: a review of original literature and recommendations for future handling

“…The chromosomes involved in pigmentary mosaicism were the following: 2 [ 22 , 23 ], 3 [ 24 – 26 ], 4 [ 27 – 30 ], 5 [ 31 , 32 ], 7 [ 33 – 42 ], 8 [ 43 ], 9 [ 29 , 44 , 45 ], 10 [ 46 ], 12 [ 16 , 47 , 48 ], 13 [ 4 , 16 , 17 , 49 – 57 ], 14 [ 30 , 54 , 58 ], 15 [ 59 – 61 ], 16 [ 62 ], 18 [ 16 , 30 , 43 , 63 – 66 ], 20 [ 67 – 71 ], 22 [ 43 , 72 ], and the sex chromosomes [ 15 , 16 , 30 , 73 – 80 ]. Furthermore, mosaic states with translocations between chromosomes 1, 6, 12, 13, 14 and 21 were found [ 81 – 83 ].…”

Hypomelanosis of Ito: pigmentary mosaicism with immature melanosome in keratinocytes

“…Hypomelanosis of Ito, recently designed as pigmentary mosaicism, was previously named incontinentia pigmenti achromians. It is a rare genetic disorder of pigmentation corresponding to a wide variety of trisomy mosaicisms (chromosomes 7, 8, 10, 13, 18, 20, …) 1–7 . Its clinical expression is variable among patients and commonly involved a series of organs.…”

Investigação citogenética em indivíduos com mosaico pigmentar do tipo Ito

“…Essas alterações submicroscópicas podem determinar mosaicismo genético e não serem diagnosticadas por citogenética, necessitando de técnicas mais sensíveis para sua detecção (29,167). Aneussomias submicroscópicas próximas a pontos de quebra foram relatadas em muitos casos em que as alterações eram aparentemente balanceadas e não estavam em mosaico (106,200,(207)(208)(209). Esses estudos demonstraram deleções e duplicações críticas, ou disrupção gênica no ponto de quebra.…”