Intelligent Ratio: A New Method for Carrier and Newborn Screening in Spinal Muscular Atrophy.

Aim: Spinal muscular atrophy (SMA) is an inherited, autosomal recessive neuromuscular disease that causes high morbidity and mortality. The prevalence is 1-2/100,000, while the incidence is 1/6000-1/10,000 among live births. Due to the high carrier frequency (1/40-1/60) of SMA-associated alleles, screening can prevent new cases. The aim of the current study was to present the development of a new, quantitative, real-time, polymerase chain reaction (PCR)-based screening test that uses an intelligent ratio (IR) for analyses, as well as a comparison of the results with the gold standard. Materials and Methods: Included in the study were 100 patients with various risk genotypes for survivor motor neuron 1 (SMN1) and SMN2 genes whose genetics had been previously investigated using multiplex ligation probe amplification (MLPA). A combination of the 5' nuclease assay and allele-specific PCR was used to quantify the SMN1 deletion mutation with real-time PCR using the FII gene as a reference. All of the optimized standards were adapted to software that provided automated analyses. The approval number of the institutional ethics committee for the study is 2012-KAEK-15/1497. Results: The results of the screening test were completely compatible with the MLPA results; it achieved 100% sensitivity and specificity compared with the gold standard. The use of the IR in the analyses provided a user-independent method that quickly and accurately provided results, regardless of the amount of DNA used of the extraction method. Conclusion: Carrier or newborn screening of SMA is essential in countries that have high rates of consanguineous marriages. The screening test presented in this study that uses FII as a reference gene proved to be low-cost, reliable, applicable, accurate, and amenable to use in an automated system for SMA screening.

Hypopigmented patches in Roberts/SC phocomelia syndrome occur via aneuploidy susceptibility.

Roberts/SC phocomelia syndrome (RBS/SC) is a rare autosomal recessive inherited condition characterized by prenatal-onset growth retardation, craniofacial anomalies, and symmetrical limb reduction defects. Here, we present two affected siblings with RBS/SC who have consanguineous parents. Both patients had intrauterine growth retardation; similar facial findings, including arched eyebrows, epicanthic folds, posteriorly angulated ears, and retrognathia; and hypopigmented patches on their skin. However, despite these common findings, the extremity involvement was different between the patients. The more severely affected boy had hypoplasia of the tibia and symmetrical agenesis of the radius, ulna, proximal carpal bones, and fibula. The slightly affected girl presented with mild symmetrical mesomelic shortening. The cytogenetic analysis showed aneuploidies at varying rates concerning different chromosomes in the analyses of different culture materials. As a remarkable finding in the cytogenetic studies, chromosome analysis of fibroblast cultures obtained from the hypopigmented skin region showed a much higher frequency of aneuploidy, especially trisomy 7, than normopigmented skin fibroblasts and lymphocyte cultures for both patients, which was also proven ex vivo by qPCR analyses from uncultured skin tissues. In the subsequent ESCO2 gene sequence analysis, both patients were found to be homozygous for the mutation c.1111dupA (p.Thr371Asnfs*32; NM_001017420.2), which is known to be pathogenic. In the literature search, only two RBS/SC patient reports with hypopigmented skin patches could be found. In addition, the presence of pigmentation defects in the embryo was reported in some different animal models for RBS/SC. When the literature review and study are evaluated together, hypopigmented patches can be considered as a rare finding for RBS/SC. It can be suggested that somatic aneuploidies seen in the natural course of the disease, especially aneuploidy of chromosome 7, which has many genes associated with pigmentation, may be responsible for the hypopigmentation patches.

The relation between isolated micropenis in childhood with CAG and GGN repeat polymorphisms in the androgen receptor gene

Background/aim: In micropenis cases accompanied by external genital abnormalities such as hypospadias and cryptorchidism, infertility and spermatogenic failures have been reported to correlate with androgen receptor ( AR ) gene CAG and GGN repeat polymorphisms. While there is one study on isolated micropenis and CAG repeats, no study related to GGN repeats has been reported. We investigated the relation between CAG and GGN repeats in the AR gene with development of penis length in boys with isolated micropenis. Materials and methods: A total of 24 Turkish boys with isolated micropenis (<­2.5 SD) and 64 healthy controls who had normal basal serum gonadotropin levels were examined. Genotyping was performed by DNA sequencing of the patients and controls. Results: The distribution of CAG and GGN repeat lengths in our patients and controls was within the normal range and did not significantly differ between the patients and the controls. Conclusion: CAG repeat length in the AR constitutes one of multiple genetic factors relevant to the development of isolated micropenis, and the expansion of this repeat can be detected as a likely modifying factor. Moreover, the interactions of other genes that may be involved in the etiology of isolated micropenis with CAG and GGN repeats have to be taken into consideration.

Development of a new real-time PCR screening kit for HbS and common beta-thalassemia mutations observed in Turkey.

BACKGROUND/AIM: IVSI-110 (G>A), IVSI-6 (T>C), IVSII-1 (G>A), IVSII-745 (C>G), IVSI-1 (G>A), and HbS are mutations covering 76% of all the ß-globin mutations in the Turkish population. In this study, our aim is to develop a reliable, fast, real-time kit for these mutations using the TaqMan probe method. MATERIALS AND METHODS: This study included 100 individuals with beta-thalassemia or sickle cell anemia who had unknown mutations, and 21 controls with known mutations. RESULTS: We designed a kit containing the IVSI-110 (G>A), IVSI-6 (T>C), IVSII-1 (G>A), IVSII-745 (C>G), IVSI-1 (G>A), and HbS mutations by using the real-time PCR method. One hundred patients were studied with our developed TaqMan real-time PCR kit. Of these patients, 73 (73%) were identified with the beta gene mutation. Among those 73 patients, 16 were homozygous, 54 were heterozygous, and 3 were compound heterozygous. CONCLUSION: This reliable kit provided rapid diagnosis including 76% of the ß-thalassemia mutations in Turkey.