Incidence of Down syndrome in Dubai, UAE

To describe incidence of Down syndrome in Dubai, United Arab Emirates [UAE]. A total of 63,398 newborn babies in Dubai [24,250 UAE nationals and 39,148 non-UAE] during a 5-year period of 1999-2003 were routinely examined by experienced nurses, neonatologists, pediatricians and/or general practitioners for symptoms of Down syndrome. Those suspected with Down syndrome were referred to the cytogenetic laboratory for karyotyping. A total of 141 cases were confirmed cytogenetically as Down syndrome. Of these, 139 were trisomy 21 and of the remaining 2, 1 was a translocation and the other a mosaic. Theoverall incidence of Down syndrome in Dubai was 1/449 live births [2.2 per 1,000]; 1/319 live births [3.13 per 1,000] among UAE nationals and 1/602 live births [1.66 per 1,000] among non-UAE nationals. The mean maternal age of UAE national mothers was 33.48 ' 8.08, with 41.66% of the mothers being in the advanced maternal age group [>35 years]. The higher incidence of Down syndrome among UAE nationals is comparable to incidences reported for other Arab populations in the Middle Eastern region. Advanced maternal age, with mothers bearing children until their 50s and higher parity, appear to be the major contributing factors for the increased incidence. The study indicates the need to provide efficient genetic counseling and to introduce an effective antenatal screening program and prenatal diagnostic services to reduce the psychological and genetic burden on the families and community

46,X,psu idic [pter-> q26:: q26-> pter] / 45,X mosaicism in a patient with premature ovarian failure

A 30 years old female with premature ovarian failure [POF] was referred to the cytogenetic lab for chromosome analysis because of secondary amenorrhea. She appeared to be normal with no stigmata of Turner syndrome There was no family history of any reproductive abnormalities. Routine G-band chromosome analysis showed an abnormal female karyotype with mosaicism for X-chromosome. Twenty-two of the 45 metaphases analyzed had 45,X chromosome complement while the remaining 23 metaphases had 46 chromosomes with one normal X chromosome and one pseudo isodicentric X chromosome involving breakpoint at Xq26.X-chromosome mosaicism and/or deletions involving Xq is usually associated with abnormal sexual development and reproductive performance often with POF. Two specific regions on Xq have been defined in the literature as POF loci, POFI at Xq26-q28 and POF2 at Xq13.3-q21. detail clinical assessment of our patient revealed the presence of possible functional oocytes and she opted for IVF. Variant Turner with mosaicism involving pseudo isodicentric [x] [q26] is very rare. Possible mechanism of the origin of the two cell lines and their correlation with POF in our patient is discussed