Hereditary Persistence of Fetal Hemoglobin (HPFH) is characterized by persistent high levels of fetal hemoglobin (HbF) in adults. Several contributory factors, both genetic and environmental, have been identified 1, but others remain elusive. Ten of twenty-seven members from a Maltese family presented with HPFH. A genome-wide SNP scan followed by linkage analysis revealed a candidate region on chromosome 19p13.12–13. Sequencing identified a nonsense mutation in the KLF1 gene, p.K288X, ablating the DNA binding domain of this key erythroid transcriptional regulator 2. Only HPFH family members were heterozygote carriers of this mutation. Expression profiling on primary erythroid progenitors revealed down-regulation of KLF1 target genes in HPFH samples. Functional assays demonstrated that, in addition to its established role in adult globin expression, KLF1 is a critical activator of the BCL11A gene, encoding a suppressor of HbF expression 3. These observations provide a rationale for the effects of KLF1 haploinsufficiency on HbF levels.

In vitro DNA amplification and dot blot analysis with synthetic allele specific oligonucleotides (ASO) identified the beta + IVS, I-6 (T --> C) thalassaemia in 78% of 32 chromosomes from 16 beta-thalassaemia homozygotes in Malta. The preponderance of a single thalassaemia mutation in one population is unusual. The beta + IVS, I-6C thalassaemia mutation was also found in three carriers who had an associated beta globin heterozygosity, i.e. Hb Valletta (or alpha 2 beta 2 87PRO) or Hb S (or alpha 2 beta 2 6VAL). The proportion of Hb A in these cases (av. = 29.7%) provided objective documentation of the relatively mild effect of this mutation on in vivo globin gene expression. However, the expression of homozygous disease was more severe in developing children compared to adults. The beta + IVS, I-6C mutation complicates population testing because heterozygotes can have Hb A2 levels below those classically associated with beta thalassaemia.

AimA collaborative exercise with several institutes was organized by the Forensic DNA Service (FDNAS) and the Institute of the Legal Medicine, 2nd Faculty of Medicine, Charles University in Prague, Czech Republic, with the aim to test performance of different laboratories carrying out DNA analysis of relatively old bone samples.MethodsEighteen laboratories participating in the collaborative exercise were asked to perform DNA typing of two samples of bone powder. Two bone samples provided by the National Museum and the Institute of Archaelogy in Prague, Czech Republic, came from archeological excavations and were estimated to be approximately 150 and 400 years old. The methods of genetic characterization including autosomal, gonosomal, and mitochondrial markers was selected solely at the discretion of the participating laboratory.ResultsAlthough the participating laboratories used different extraction and amplification strategies, concordant results were obtained from the relatively intact 150 years old bone sample. Typing was more problematic with the analysis of the 400 years old bone sample due to poorer quality.ConclusionThe laboratories performing identification DNA analysis of bone and teeth samples should regularly test their ability to correctly perform DNA-based identification on bone samples containing degraded DNA and potential inhibitors and demonstrate that risk of contamination is minimized.

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