NGS-driven molecular diagnosis of heterogeneous hereditary neurological disorders reveals novel and known variants in disease-causing genes

Hereditary neurological disorders (HNDs) are a clinically and genetically heterogeneous group of disorders. These disorders arise from the impaired function of the central or peripheral nervous system due to aberrant electrical impulses. More than 600 various neurological disorders, exhibiting a wide spectrum of overlapping clinical presentations depending on the organ(s) involved, have been documented. Owing to this clinical heterogeneity, diagnosing these disorders has been a challenge for both clinicians and geneticists and a large number of patients are either misdiagnosed or remain entirely undiagnosed. Contribution of genetics to neurological disorders has been recognized since long; however, the complete picture of the underlying molecular bases are under-explored. The aim of this study was to accurately diagnose 11 unrelated Pakistani families with various HNDs deploying NGS as a first step approach. Using exome sequencing and gene panel sequencing, we successfully identified disease-causing genomic variants these families. We report four novel variants, one each in, ECEL1, NALCN, TBR1 and PIGP in four of the pedigrees. In the rest of the seven families, we found five previously reported pathogenic variants in POGZ, FA2H, PLA2G6 and CYP27A1. Of these, three families segregate a homozygous 18 bp in-frame deletion of FA2H, indicating a likely founder mutation segregating in Pakistani population. Genotyping for this mutation can help low-cost population wide screening in the corresponding regions of the country. Our findings not only expand the existing repertoire of mutational spectrum underlying neurological disorders but will also help in genetic testing of individuals with HNDs in other populations.

Genetic analysis of osteopetrosis in Pakistani families identifies novel and known sequence variants

Osteopetrosis is a genetically heterogenous, fatal bone disorder characterized by increased bone density. Globally, various genetic causes are reported for osteopetrosis with all forms of inheritance patterns. A precise molecular diagnosis is necessary for prognosis and for prescribing treatment paradigms in osteopetrosis. Here we report on thirteen individuals diagnosed with infantile malignant osteopetrosis coming from ten unrelated Pakistani families; nine of whom are consanguineous. We performed whole exome sequencing and Sanger sequencing in all families and identified homozygous variants in genes previously reported for autosomal recessive inheritance of osteopetrosis. All the identified variants are expected to affect the stability or length of gene products except one nonsynonymous missense variant. TCIRG1 was found as a candidate causal gene in majority of the families. We report six novel variants; four in TCIRG1 and one each in CLCN7 and OSTM1. Our combined findings will be helpful in molecular diagnosis and genetic counselling of patients with osteopetrosis particularly in populations with high consanguinity.

Epidemiology of aplastic anemia: a study of 1324 cases

Objective: Prevalence of aplastic anemia (AA) is high in the Asian population. This study was done to explore the etiology and association of AA with various socio-economic and environmental factors.Study design and setting: Study included 1324 consecutive AA cases registered at Armed Forces Bone Marrow Transplant Centre Rawalpindi, Pakistan, from March 2001 to August 2016. The study questionnaire was completed through an interview. It included patients' socio-demographic details, personal and family medical history, environmental attributes and clinico-hematological features.Results: The median age of patients was 20 years, 997 were male and 327 female. Distribution of non-severe, severe and very severe AA was 230 (17.4%); 598 (45.2%) and 496 (37.4%), respectively. The majority of patients were from low (n = 761, 57.5%) or middle socioeconomic class (n = 543, 41%). Consanguinity among patients (n = 806, 61%) was slightly higher than the national statistics. History of chemical exposures included fertilizers (n = 116, 8.7%), pesticides (n = 56, 4.2%) and industrial chemicals (n = 37, 2.8%). PNH clone was found in 63 of AA patients. After excluding 298 patients undergoing HSCT and 660 deaths/lost to follow-up, disease evolution was observed in 38(10.4%) patients out of 366 evaluable patients. These included PNH = 18, MDS = 11 and AML = 9.Discussion: Due to lack of funding and adequate human resource at the center, age and sex-matched controls could not be included. Other limitations were a lack of molecular testing to exclude the possibility of inherited bone marrow failure syndromes on a genetic basis.Conclusion: Younger age, male predominance and higher consanguinity point toward genetic factors in AA etiology among the South Asian population.

Comparison of Conventional Cyclophosphamide versus Fludarabine-Based Conditioning in High-Risk Aplastic Anemia Patients Undergoing Matched-Related Donor Transplantation

Allogeneic stem cell transplant for high-risk aplastic anemia (AA) yields inferior results using conventional cyclophosphamide (CY)-based conditioning. The use of fludarabine (Flu)-based regimens has resulted in improved outcomes in high-risk patients. Limited data are available comparing these two conditioning regimens in such patients. We retrospectively analyzed 192 high-risk patients undergoing matched-related donor transplantation from July 2001 to December 2018. The median age was 19.5 (2–52) years. Patients were divided into 2 groups, Cy²⁰⁰ anti-thymocyte globulin (ATG)²⁰ (Gp1 n = 79) or Flu^120–150 Cy^120–160 ATG²⁰ (Gp2 n = 113). The risk of graft failure was significantly higher in Gp1, and the majority occurred in patients with >2 risk factors (p = 0.02). The incidence of grade II-IV acute graft versus host disease (GVHD) and chronic GVHD was not significantly different between the two groups. The overall survival (OS) of the study cohort was 81.3 %, disease-free survival (DFS) 76.6 % and GVHD-free relapse-free survival (GRFS) was 64.1%. DFS and GRFS were significantly higher in Gp2 as compared to Gp1: DFS 84.1% versus 68.4 % (p = 0.02), GRFS 77.9% versus 54.4% (p = 0.01), respectively. We conclude that Flu-based conditioning is associated with superior OS, DFS and GRFS as compared to the conventional Cy-based regimen in high-risk AA.

Screening of the FANCA gene mutational hotspots in the Pakistani fanconi anemia patients revealed 19 sequence variations

Fanconi anemia (FA) is a recessive disorder that predispose to bone marrow failure and multiple congenital anomalies in affected individuals worldwide. To date, 22 FA genes are known to harbor sequence variations in disease phenotype. Among these, mutations in the FANCA gene are associated with 60% to 70% of FA cases. The aim of the present study was to screen FA cases belonging to consanguineous Pakistani families for selected exons of FANCA gene which are known mutational hotspots for Asian populations. Blood samples were collected from 20 FA cases and 20 controls. RNA was extracted and cDNA was synthesized from blood samples of cases. DNA was extracted from blood samples of cases and ethnically matched healthy controls. Sanger's sequencing of the nine selected exons of FANCA gene in FA cases revealed 19 genetic alterations of which 15 were single nucleotide variants, three were insertions and one was microdeletion. Of the total 19 sequence changes, 13 were novel and six were previously reported. All identified variants were evaluated by computational programs including SIFT, PolyPhen-2 and Mutation taster. Seven out of 20 analyzed patients were carrying homozygous novel sequence variations, predicted to be associated with FA. These disease associated novel variants were not detected in ethnically matched controls and depict genetic heterogeneity of disease.

Epidemiological, clinical and genetic characterization of aplastic anemia patients in Pakistan

Aplastic anemia (AA) is the most serious non-malignant blood disorder in Pakistan, ranked second in prevalence, after thalassemia. We investigated various epidemiological, clinical, and genetic factors of AA in a Pakistani cohort of 214 patients reporting at our hospital between June 2014 and December 2015. A control group of 214 healthy subjects was included for comparison of epidemiological and clinical features. Epidemiological data revealed 2.75-fold higher frequency of AA among males. A single peak of disease onset was observed between ages 10 and 29 years followed by a steady decline. AA was strongly associated with lower socioeconomic profile, rural residence, and high rate of consanguineous marriages. Serum granulocyte colony-stimulating factor and thrombopoietin levels were significantly elevated in AA patients, compared to healthy controls (P < 0.0001), while there was no statistical significance in other nine cytokine levels screened. Allele frequencies of DRB1*15 (56.8%) and DQB1*06 (70.3%) were predominantly high in AA patients. Ten mutations were found in TERT and TERC genes, including two novel mutations (Val526Ala and Val777Met) in exons 3 and 7 of TERT gene. Despite specific features of the AA cohort, this study suggests that epidemiologic and etiologic factors as well as host genetic predisposition exclusively or cooperatively trigger AA in Pakistan.

Autologous mesenchymal stromal cell transplantation for spinal cord injury: A Phase I pilot study

BACKGROUND AIMS

Mesenchymal stromal cell (MSC) transplantation has immerged as promising therapeutic approach to treat spinal cord injury (SCI). In this pilot study, we investigated the safety of intrathecal injection of autologous bone marrow-derived MSCs in nine patients with SCI.

METHODS

Patients with complete SCI at the thoracic level were divided into two groups: chronic (>6 months, group 1) and sub-acute SCI (<6 months, group 2), according to time elapsed since injury. MSCs were isolated by density gradient separation of autologous bone marrow harvested from the iliac crest. Cells were cultured in a Good Manufacturing Practice-compliant facility to produce clinical scale dose. After quality control testing, MSCs were injected back to patients by intrathecal injection. Safety was defined as absence of adverse event and side effects after 1 month after receiving the injection.

RESULTS

Six patients had chronic SCI with a median duration of 33 months since date of injury (range: 10-55 months), and three patients were in sub-acute phase of disease. Each patient received two or three injections with a median of 1.2 × 10(6) MSCs/kg body weight. No treatment-related adverse event was observed during median follow-up of 720 days (range: 630-826 days) in group 1 and 366 days (range: 269-367 days) in group 2, respectively.

DISCUSSION

This pilot study demonstrated that autologous MSCs can be safely administered through intrathecal injection in spinal cord injury patients. Further investigation through randomized, placebo-controlled trials is needed.

Polymorphism in the IL-8 Gene Promoter and the Risk of Acne Vulgaris in a Pakistani Population

Interleukin-8 (IL-8) is a well-known inflammatory chemokine and suggested to be involved in the development of acne vulgaris. This study investigates IL-8 plasma levels in acne patients and healthy controls and the molecular basis for the regulation of the IL-8 gene in a Pakistani population. Patients with acne vulgaris (n = 264) and healthy individuals (n = 264) were enrolled in this investigation. Plasma IL-8 levels were determined by enzyme-linked immunosorbent assay (ELISA). The genotyping for IL-8 gene was performed by polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP). Our data showed a statistically significant increase in IL-8 levels from acne patients compared with healthy subjects (154.2 ± 52.1 pg/mL in patients vs. 101.6 ± 33.5 pg/mL in controls, p<0.0001). The IL-8-251T>A (rs4073) polymorphism was significantly higher in patients with acne compared with the control group (p=0.013). There was a significant difference between the T and A alleles from acne cases and controls (odds ratio OR=1.6,95 % CI= 1.16-2.19, p=0.003). Logistic-regression analysis showed that the increased IL-8 levels, and the IL-8-251T>A polymorphism were significantly associated with acne. Our data suggest that the elevated IL-8 levels and the IL-8-251T>A polymorphism may be associated with acne vulgaris in the study population.

Outcome of allogeneic haematopoietic stem cell transplantation in aplastic anaemia

OBJECTIVE

To analyze factors associated with survival, rejection and graft versus host disease in aplastic anaemia patients undergoing allogeneic haematopoietic stem cell transplantation (SCT) from HLA matched sibling donors.

STUDY DESIGN

Analytical study.

PLACE AND DURATION OF STUDY

Armed Forces Bone Marrow Transplant Centre, Rawalpindi, Pakistan from July 2001 to June 2010.

METHODOLOGY

Consecutive aplastic anaemia (AA) patients undergoing haematopoietic stem cell transplantation from HLA-matched sibling donors at this centre were included in this study. Potential factors affecting overall survival, rejection, disease-free survival and graft versus host disease were analyzed. Survival analysis was done by Kaplan-Meier method. Cox regression model was applied for multivariate analysis.

RESULTS

Ninety male and thirty-five female patients with AA were included in the study. Median age was 18 years. Conditioning regimens used were cyclophosphamide (Cy) plus antilymphocyte globulin (ALG) or antithymocyte globulin (ATG), fludarabine (FLU) +Cy+ATG, Campath 1-H +Cy in 89, 30 and 6 cases respectively. GVHD prophylaxis used was ciclosporin (CSA) plus prednisolone and short methotrexate in 81 while 44 received CSA plus prednisolone. At a median follow-up of 1185 days OS and DFS were 84% and 78% respectively. Factors associated with better OS were male sex, Flu/Cy/ATG conditioning and use of bone marrow as stem cell source.

CONCLUSION

Flu/Cy/ATG conditioning regimen, bone marrow as stem cell source and CSA, prednisolone and short methotrexate regimen were associated with better survival in AA.