Expanded Newborn Screening in Italy Using Tandem Mass Spectrometry: Two Years of National Experience.

Newborn screening (NBS) for inborn errors of metabolism is one of the most advanced tools for secondary prevention in medicine, as it allows early diagnosis and prompt treatment initiation. The expanded newborn screening was introduced in Italy between 2016 and 2017 (Law 167/2016; DM 13 October 2016; DPCM 12-1-2017). A total of 1,586,578 infants born in Italy were screened between January 2017 and December 2020. For this survey, we collected data from 15 Italian screening laboratories, focusing on the metabolic disorders identified by tandem mass spectrometry (MS/MS) based analysis between January 2019 and December 2020. Aminoacidemias were the most common inborn errors in Italy, and an equal percentage was observed in detecting organic acidemias and mitochondrial fatty acids beta-oxidation defects. Second-tier tests are widely used in most laboratories to reduce false positives. For example, second-tier tests for methylmalonic acid and homocysteine considerably improved the screening of CblC without increasing unnecessary recalls. Finally, the newborn screening allowed us to identify conditions that are mainly secondary to a maternal deficiency. We describe the goals reached since the introduction of the screening in Italy by exchanging knowledge and experiences among the laboratories.

Novel mutations in two unrelated Italian patients with SSADH deficiency.

Succinic semialdehyde dehydrogenase deficiency (SSADHD) is a rare autosomal recessive disorder of γ-aminobutyric acid (GABA) catabolism caused by mutations in the gene coding for succinic semialdehyde dehydrogenase (ALDH5A1). The abnormal levels of GHB detected in the brain and in all physiological fluids of SSADHD patients represent a diagnostic biochemical hallmark of the disease. Here we report on the clinical and molecular characterization of two unrelated Italian patients and the identification of two novel mutations: a 22 bp DNA duplication in exon 1, c.114_135dup, p.(C46AfsX97), and a non-sense mutation in exon 10, c.1429C > T, p.(Q477X). The two patients showed very different clinical phenotypes, coherent with their age. These findings enrich the characterization of SSADHD families and contribute to the knowledge on the progression of the disease.

Rapid multiplex real-time PCR by molecular beacons for different BRAF allele detection in papillary thyroid carcinoma.

BRAF is an oncogene that is commonly mutated in both melanomas and papillary thyroid carcinomas (PTCs). Usually, mutations in the codons 600 or 601 lead to constitutive activity in the Ras-mitogen-activated protein kinase pathway and, recently, the BRAF deletion was described as a relevant risk factor for loco-regional PTC lymph node metastasis. For these reasons, BRAF mutations may be considered a key genetic factor for the metastatic progression of PTC and also for other tumors such as melanoma and colon cancer and a new BRAF-specific therapeutic strategy was already suggested. In this report we describe the development of a rapid qualitative fluorescent real-time polymerase chain reaction assay designed for the detection of BRAF deletion using 2 specific molecular beacons. The assay is able to detect in a single tube the homozygous as well the heterozygous genotypes. The procedure combines the great sensitivity of the polymerase chain reaction, the specificity provided by allele-specific molecular beacons, and the throughput of a multicolor fluorescence detection procedure. This technique, together with an earlier described real-time test specific for V600E and K601E will be useful for research and molecular diagnostic laboratories involved in the study of BRAF-related neoplasia.

Liver repopulation by transplanted hepatocytes and risk of hepatocellular carcinoma.

BACKGROUND: Transplantation of isolated hepatocytes in rats treated with retrorsine (RS) results in massive repopulation of the host liver. In this study, the long-term fate of hepatocytes transplanted into RS-treated recipients was followed for up to two years. METHODS: Dipeptidyl-peptidase type IV-deficient (DPPIV) Fischer 344 rats were given two injections of RS (30 mg/kg), followed by transplantation of 2 million hepatocytes, isolated from a syngenic, DPPIV donor. RESULTS: Extensive (91+/-7%) liver replacement by transplanted hepatocytes was observed in animals sacrificed 18 months posttransplantation. Similar levels of repopulation persisted at two years (87+/-5%). No evidence of preneoplastic and/or neoplastic evolution of the transplanted cell population was present in the RS-treated and repopulated livers at any time point considered. Furthermore, serum parameters related to hepatocyte function and integrity were in the normal range. In control groups given cell transplantation in the absence of prior treatment with RS, only small clusters of donor-derived, DPPIV hepatocytes were discerned. CONCLUSIONS: These results indicate that liver repopulation in this model is largely stable, persisting for up to two years and allowing for a normal liver function. In addition, no increased risk of neoplastic transformation appears to be associated with the process of liver repopulation for as long as over two thirds of the life span of the recipient animal.

Rapid PCR real-time genotyping of M-Malton alpha1-antitrypsin deficiency alleles by molecular beacons.

Alpha1-Antitrypsin deficiency is an autosomal codominant inherited disorder, with increased risk of developing lung and liver disease. The large majority of subjects affected by alpha1-antitrypsin deficiency carry the PIZZ or PISZ genotypes, which can be easily detected using several molecular methods. Another pathologic allele, the M-Malton variant (also known as Mnichinan and Mcagliari), can mimic the Pi Z clinical phenotype, but this alpha1-antitrypsin deficiency variant is not easily recognizable and, therefore, seems to be more under-recognized than the Z or S alleles. We report the development of a rapid qualitative fluorescent real-time PCR assay designed for the detection of the M-Malton alpha1-antitrypsin deficiency alleles using 2 specific molecular beacons. The assay is able to detect in a single tube the homozygous as well the heterozygous genotypes. The procedure combines the great sensitivity of the polymerase chain reaction, the specificity provided by allele-specific molecular beacons, and the throughput of a multi-color fluorescence detection procedure. This technique will be useful for research and molecular diagnostic laboratories involved in the study of alpha1-antitrypsin deficiency-related diseases.