Fraisse J, Philip T, Bertheas M F, Lauras B
Ann Genet. 1986;29(3):177-80.
Six probands, apparently not related, with a minimal phenotype of Down's syndrome were investigated between 1970 and 1984 in our laboratory. We found in all of them an identical chromosomal abnormality 46,XX or XY,-21,+ der21(dupq22delp23). The der 21 was due to aneusomie de recombinaison, each mother having an abnormal chromosome 21: inv(21)(p12;q22). The fathers' caryotypes were normal. All parents were young and healthy. Pedigrees were established in order to find a relationship between these families. Four of our probands could be related. Familial investigations are still in progress for the last two cases; the ancestors being born in the same small geographical area (within 50 km2) we think that we shall be able to establish a relationship with the others families.
1970年至1984年间，我们实验室对6名明显无血缘关系、具有唐氏综合征最小表型的先证者进行了研究。我们在他们所有人中都发现了相同的染色体异常：46,XX或XY，-21，+ der21（dupq22delp23）。der21是由于重组非整倍体导致的，每位母亲都有一条异常的21号染色体：inv(21)(p12;q22)。父亲的核型正常。所有父母都年轻且健康。绘制了家系图以寻找这些家庭之间的关系。我们的6名先证者中有4名可能存在亲缘关系。对最后两例的家族调查仍在进行中；由于这些家族的祖先都出生在同一个小地理区域（50平方公里以内），我们认为能够与其他家族建立联系。
