Mapping autosomal recessive intellectual disability: combined microarray and exome sequencing identifies 26 novel candidate genes in 192 consanguineous families.

Approximately 1% of the global population is affected by intellectual disability (ID), and the majority receive no molecular diagnosis. Previous studies have indicated high levels of genetic heterogeneity, with estimates of more than 2500 autosomal ID genes, the majority of which are autosomal recessive (AR). Here, we combined microarray genotyping, homozygosity-by-descent (HBD) mapping, copy number variation (CNV) analysis, and whole exome sequencing (WES) to identify disease genes/mutations in 192 multiplex Pakistani and Iranian consanguineous families with non-syndromic ID. We identified definite or candidate mutations (or CNVs) in 51% of families in 72 different genes, including 26 not previously reported for ARID. The new ARID genes include nine with loss-of-function mutations (ABI2, MAPK8, MPDZ, PIDD1, SLAIN1, TBC1D23, TRAPPC6B, UBA7 and USP44), and missense mutations include the first reports of variants in BDNF or TET1 associated with ID. The genes identified also showed overlap with de novo gene sets for other neuropsychiatric disorders. Transcriptional studies showed prominent expression in the prenatal brain. The high yield of AR mutations for ID indicated that this approach has excellent clinical potential and should inform clinical diagnostics, including clinical whole exome and genome sequencing, for populations in which consanguinity is common. As with other AR disorders, the relevance will also apply to outbred populations.

Genetic associations of psoriasis in a Pakistani population.

BACKGROUND: Genetic predisposition to psoriasis, an inflammatory skin disease affecting 0·2-4% of the world population, is well established. Thus far, 41 psoriasis susceptibility loci reach genome-wide significance (P ≤ 5 × 10(-8) ). Identification of genetic susceptibility loci in diverse populations will help understand the underlying biology of psoriasis susceptibility. OBJECTIVES: The primary objective of this study was to examine psoriasis susceptibility associations previously reported in Chinese and caucasian populations in a Pakistani cohort. METHODS: Blood samples and phenotype data were collected from psoriasis cases and controls in Islamabad, Pakistan. DNA was isolated and genotypes of selected susceptibility markers were determined. The data were analysed using χ(2) tests or logistic regression for psoriasis association. RESULTS: HLA-Cw6 showed the strongest association [odds ratio (OR) 2·43, P = 2·3 × 10(-12) ]. HLA-Cw1 showed marginally significant association (OR 1·66, P = 0·049), suggesting that the HLA-Cw1-B46 risk haplotype may be present in the Pakistani population. Three other loci (IL4/IL13, NOS2, TRAF3IP2) showed nominally significant association (P < 0·05). CONCLUSIONS: HLA-Cw6 is strongly associated with psoriasis susceptibility in the Pakistani population, as has been found in every other population studied. In addition, HLA-Cw1 showed marginal association, reflecting the relative geographical proximity and thus likely genetic relatedness to other populations in which the HLA-Cw1-B46 haplotype is known to be associated. A larger cohort and a denser marker set will be required for further analysis of psoriasis associations in the South Asian population.

SABRE-B: an evaluation of paclitaxel and bevacizumab with or without sunitinib as first-line treatment of metastatic breast cancer.

BACKGROUND: The vascular endothelial growth factor (VEGF) pathway can be targeted through VEGF neutralization or VEGF receptor (VEGFR) blockade using tyrosine kinase inhibition. Because laboratory models suggest that combining these approaches might be synergistic, we sought to evaluate the feasibility and efficacy of combining sunitinib with paclitaxel + bevacizumab (PB). METHODS: Patients with human epidermal growth factor receptor 2 (HER2)-negative, metastatic breast cancer receiving first-line chemotherapy were randomized to PB or PB with sunitinib (PBS), with planned escalation of the sunitinib dose. RESULTS: Forty-six patients were randomized to PB or PBS with sunitinib dosed at 25 mg p.o. daily. Patients receiving PBS encountered substantial toxicity that precluded adequate treatment. The percentage of patients with grade ≥3 adverse events was greater in the PBS arm than the PB arm (83% versus 57%), and sunitinib dosing was modified in 78% of patients, most often due to neutropenia, febrile neutropenia, and fatigue. In addition, 44% of patients had sunitinib dose reduction to 12.5 mg, and 39% required discontinuation. Patients receiving PBS had more bevacizumab treatment interruptions and discontinuations because of toxicity. Median treatment duration was longer in the PB arm compared with the PBS arm (14.1 versus 11.1 weeks), reflecting early treatment discontinuation of PBS. Because of poor tolerability of the addition of sunitinib to PB, the planned sunitinib dose escalation was halted and the study accrual was terminated. CONCLUSION: Adding sunitinib to standard doses of bevacizumab plus paclitaxel for metastatic breast cancer is not feasible. Different strategies will be required to evaluate whether there is additional clinical benefit to combining VEGF/VEGFR-targeted agents.

Virulence factors profile of drug-resistant Escherichia coli isolates from urinary tract infections in Punjab, Pakistan.

Escherichia coli is considered to be the main causative agent of urinary tract infections (UTIs). The primary objective of this study was to investigate the spectrum of five virulence factors among drug-resistant clinical E. coli isolates associated with pyelonephritis and cystitis. A total of 101 samples were positive for E. coli (42 from pyelonephritis cases and 59 from cystitis cases) out of 457 urine samples of patients. Among toxins, haemolysin and secreted autotransporter toxin are found more frequently in isolates causing pyelonephritis (p < 0.020) than cystitis (p < 0.083). The frequent occurrence of P-pili, S-fimbria and protein involved in intestinal colonisation was noted among E. coli isolates associated with pyelonephritis. Overall, the study suggests that clinical isolates associated with pyelonephritis are more virulent than those associated with cystitis and diversified association with various antimicrobial resistance phenotypes was noted.

Low Seroprevalence of Torque Teno Virus in HCV positive patients and phylogenetic analysis from Pakistani isolates.

The torque teno virus (TTV) has a heterogeneous genome and its role in hepatitis C (HCV) infection is still controversial, therefore the purpose of the present study was to determine if there is any association between Hepatitis C and TTV co-infection and to determine the phylogenetic relationship between existing types in the Pakistani population. A total of 500 individuals (250 HCV positive patients and 250 healthy controls) were selected. DNA was extracted from serum samples and polymerase chain reaction (PCR) of the open reading frame 1 (ORF1) region of TTV was performed. Out of 500 samples 9 HCV positive index cases (3.6%) and 8 healthy samples (3.2%) were found to be positive for TTV. A comparison was made between TTV sequences reported from all over the world with the ones obtained in the present study by sequencing of TTV positive samples followed by phylogenetic analysis using maximum parsimony (MP) method. Our results indicated that the virus was undergoing divergent evolution as very high sequence diversity was found in the ORF1 gene. The study also shows that association between HCV and TTV was not found. Because the virus was found to be affecting both healthy individuals and HCV infected population with almost same frequency. Therefore a thorough screening of TTV virus at the population level is required in order to draw a comprehensive inference.

Identification and characterisation of novel human Y-chromosomal microsatellites from sequence database information.

1.33 Mb of sequence from the human Y chromosome was searched for tri- to hexanucleotide microsatellites. Twenty loci containing a stretch of eight or more repeat units with complete repeat sequence homo-geneity were found, 18 of which were novel. Six loci (one tri-, four tetra- and one pentanucleotide) were assembled into a single multiplex reaction and their degree of polymorphism was investigated in a sample of 278 males from Pakistan. Diversities of the individual loci ranged from 0.064 to 0.727 in Pakistan, while the haplotype diversity was 0.971. One population, the Hazara, showed particularly low diversity, with predominantly two haplotypes. As the sequence builds up in the databases, direct methods such as this will replace more biased and technically demanding indirect methods for the isolation of microsatellites.

Pilot study of sequential vinorelbine and cisplatin followed by docetaxel for selected IIIB and stage IV non-small cell lung cancer.

UNLABELLED: Vinorelbine, cisplatin and docetaxel are known to be efficacious in non-small cell lung cancer (NSCLC). This limited institution pilot study evaluated the novel strategy of sequencing active first line agents prior to progression. The primary objective of this study was to assess the toxicity profile in anticipation of a larger cooperative group standard phase II study. Patients with selected stage IIIB and IV NSCLC, Southwest Oncology Group (SWOG) performance status (PS) of 1 or less and measurable or evaluable disease were eligible. Treatment was cisplatin 100 mg/m(2) day 1 and 29, vinorelbine 25 mg/m(2) weekly for 8 weeks, followed by docetaxel 100 mg/m(2) every 21 days for four cycles if no progression. If grade IV neutropenia developed, G-CSF 5 mcg/kg/day was used in subsequent cycles. Of 18 eligible patients, 17 patients had stage IV disease with a median age of 66 years (range 48-80). Eight patients had a SWOG PS of 1, 10 had a PS of zero. Six of eighteen patients received all 8 weeks of vinorelbine/cisplatin and six of eight patients who went on to receive docetaxel received all four planned cycles; only two patients overall received all planned therapy. One grade III/IV event each of cardiotoxicity (myocardial infarction), renal toxicity (acute renal failure), anemia and thrombocytopenia occurred with vinorelbine and cisplatin, and 2 Grade IV hypersensitivity reactions, manifested by severe back pain with docetaxel occurred. Three deaths occurred during the study, all during treatment with vinorelbine and cisplatin: one due to neutropenic sepsis; one from a pulmonary embolism; and one secondary to severe hypoglycemia in a diabetic patient. Of the 16 patients evaluable for response after vinorelbine/cisplatin, there were two complete responses (12.5%) and three partial responses (19%) for an overall response rate of 31% (95% CI 8-58). One additional patient who received docetaxel experienced a partial response. Two patients remain alive (21+ and 18+ months, respectively). The 1-year survival was 44%. CONCLUSION: This sequence, as defined, was tolerated marginally well in patients with advanced NSCLC. Granulocytopenia was the major toxicity requiring dose adjustments throughout the sequence. Based on response rates and tolerability that were somewhat comparable to other regimens in this disease setting, a modified version of this program, adjusted to decrease the incidence of grade III and IV toxicity, was selected as one arm of a recent randomized phase II trial in the Southwest Oncology Group (SWOG), S9806, evaluating sequential therapy in advanced NSCLC.

P53 mutations, polymorphisms, and haplotypes in Pakistani ethnic groups and breast cancer patients.

Inactivation of the p53 gene has been found to be associated with the pathogenesis of several neoplasias. Three biallelic polymorphisms in the p53 gene have been linked to predisposition to the development of various malignancies. These include a 16-bp duplication in intron 3 and BstU I and Msp I restriction fragment length polymorphisms (RFLPs) in exon 4 and intron 6, respectively. The prevalence of these polymorphisms was studied in breast cancer patients and nine major ethnic groups of Pakistan. Differences in allele frequencies for all three polymorphisms were observed among the various ethnic groups and breast cancer patients. The absence of the 16-bp duplication was common among the northern ethnic groups, being highest in the Hazara (0.90). The Msp I A1 allele frequency in the southern Makrani population was significantly higher in comparison with the other ethnic groups. In the cancer patients, the absence of the 16-bp duplication in combination with the BstU I Pro and absence of Msp I restriction site were the most frequent. In these patients, ten substitution mutations were found in the p53 gene, seven of which have been reported previously for breast cancer. The remaining three mutations have been found in other malignancies, but not in carcinoma of the breast.

Y-chromosomal STR haplotypes in Pakistani populations.

16 Y-specific STR loci have been analysed in 711 males from 12 populations in Pakistan. Individual loci showed between 4 and 10 alleles, and diversities ranged from 0.07 to 0.77. A total of 527 different haplotypes were found and the haplotype diversity ranged from 0.92 to 0.99 for the different populations. 446 haplotypes occurred in single individuals, and only 19 haplotypes were present in more than three males, but two striking examples of haplotype sharing were found, one involving 13 individuals, and the other 17. The 13 individuals were all Parsis, and 16 of the 17 were Brahuis, providing evidence for population substructuring.

Clinical profile of 100 cases of liver abscess.

One hundred patients with liver abscess were studied for clinical features and complications. They were diagnosed by radiography, ultrasonography, serology and by needle aspiration. A variety of interesting clinical, haematological and ultrasonographic findings were observed. Literature on liver abscess was reviewed and results compared.

Serodiagnosis of amoebic liver abscess by IHA method.

Serological test based on IHA (Indirect Haemagglutination Method) was performed in 100 cases of hepatic abscess. The test was 100% sensitive and 94% specific. The cut off point of antibody titer between normal population and patients with invasive amoebiasis was 1:128. Antibody titer in amoebic liver abscess was 1:5242 +/- 2795. A significant (P less than 0.001) correlation was found between total leucocyte count and antibody titer.

A Novel Familial BBS12 Mutation Associated with a Mild Phenotype: Implications for Clinical and Molecular Diagnostic Strategies.

Bardet-Biedl syndrome (BBS) is an autosomal recessively inherited ciliopathy mainly characterized by rod-cone dystrophy, postaxial polydactyly, obesity, renal tract anomalies, and hypogonadism. To date, 14 BBS genes, BBS1 to BBS14, have been identified, accounting for over 75% of mutations in BBS families. In this study, we present a consanguineous family from Pakistan with postaxial polydactyly and late-onset retinal dysfunction. Adult affected individuals did not show any renal or genital anomalies, obesity, mental retardation or learning difficulties and did thus not fulfill the proposed clinical diagnostic criteria for BBS. We mapped the disease in this family to the BBS12 locus on chromosome 4q27 and identified the novel homozygous p.S701X nonsense mutation in BBS12 in all three affected individuals of this family. We conclude that BBS12 mutations might cause a very mild phenotype, which is clinically not diagnosed by the current diagnostic criteria for BBS. Consequently, we suggest the use of less strict diagnostic criteria in familial BBS families with mild phenotypic expression.

pH dependence of the kinetic mechanism of the adenosine 3',5'-monophosphate dependent protein kinase catalytic subunit in the direction of magnesium adenosine 5'-diphosphate phosphorylation.

In order to determine the acid-base chemical mechanism of the adenosine 3',5'-monophosphate dependent protein kinase catalytic subunit, the pH dependence of the kinetic mechanism in the direction of MgADP phosphorylation has been determined using initial velocity studies in the presence and absence of dead-end inhibitors. The kinetic mechanism in the direction of MgADP phosphorylation is random, with changes in the preference of substrate binding as a function of pH. At pH 7.2 and below, the kinetic mechanism is ordered with phosphorylated peptide binding prior to MgADP. At pH 7.6, the opposite pathway with MgADP binding prior to phosphorylated peptide is preferred. The pH independence of V/Et is consistent with a mechanism in which reactants only bind to the correctly protonated form of the enzyme. The V/KMgADP value decreases, as the pH increases, giving a pK of about 7 which is likely that of a general acid, the same group that serves as a general base in the opposite reaction direction [Yoon, M.-Y., & Cook, P.F. (1987) Biochemistry 26, 4118]. The pKiPSP decreases at low pH giving a pK of about 6.5, probably reflecting the phosphate group of the peptide.

Kinetic mechanism of the adenosine 3',5'-monophosphate dependent protein kinase catalytic subunit in the direction of magnesium adenosine 5'-diphosphate phosphorylation.

In order to define the overall kinetic mechanism of adenosine 3',5'-monophosphate dependent protein kinase catalytic subunit and also to elaborate the kinetic mechanism in the direction of peptide phosphorylation, we have determined its kinetic mechanism in the direction of MgADP phosphorylation. Studies of initial velocity as a function of uncomplexed Mg2+ (Mgf) in the absence and presence of dead-end inhibitors were used to define the kinetic mechanism. Data are consistent with the overall kinetic mechanism in the direction of MgADP phosphorylation being random with both the pathways allowed, i.e., the pathway in which MgADP binds to the enzyme prior to phosphorylated peptide and the pathway in which phosphorylated peptide binds to enzyme prior to MgADP. In addition, depending on the concentration of Mgf, one or the other pathway predominates. At low (0.5 mM) Mgf, the mechanism is steady-state ordered with the pathway in which phosphorylated peptide binds first being preferred; at high (10 mM) Mgf, the kinetic mechanism is equilibrium ordered, and the pathway in which MgADP binds first is preferred. This change in mechanism to equilibrium ordered at higher concentration of Mgf is due to an increase in affinity of the enzyme for MgADP and a decrease in affinity for the phosphorylated peptide. The Haldane relationship gives a Keq of 2 +/- 1 x 10(3) at pH 7.2, in agreement with the values obtained from 31P NMR (1.6 +/- 0.8 x 10(3)) and direct determination of reactant concentrations at equilibrium (3.5 +/- 0.6 x 10(3)).

A method for counting active sites of cyclic AMP-dependent protein kinase.

A method has been developed for counting active sites of cyclic-AMP-dependent protein kinase. Known concentrations of a synthetic peptide similar to a fragment of the endogenous inhibitor of the kinase were included in otherwise routine assay mixes containing several different volumes of enzyme stock solution. The concentration of active sites of the catalytic subunit of the cyclic AMP-dependent protein kinase in the stock solution was then determined by fitting observed velocities to an equation that accounts for the presence of a tight-binding inhibitor. The method yielded estimates of catalytic subunit concentration comparable with those derived from more traditional measures of catalytic subunit concentration. Both purified and heterogeneous samples were assayed, since active-sites counting assumes only a mutually specific, high-affinity interaction between enzyme and inhibitor and does not require that samples be pure. In principle, the method can be adapted to other protein kinases for which a specific, tight-binding, reversible inhibitor is available.

African and Levantine origins of Pakistani YAP+ Y chromosomes.

We surveyed 9 Pakistani subpopulations for variation on the nonrecombining portion of the Y chromosome. The polymorphic systems examined were the Y-chromosome Alu insertion polymorphism (YAP) at DYS287, 5 single nucleotide polymorphisms, and the tetranucleotide microsatellite DYS19. Y chromosomes carrying the YAP element (YAP+) were found in populations from southwestern Pakistan at frequencies ranging from 2% to 8%, whereas northeastern populations appeared to lack YAP+ chromosomes. In contrast to other South Asian populations, several Pakistani subpopulations had a high frequency of the DYS19*B allele, the most frequent allele in West Asian, North African, and European populations. The combination of alleles at all polymorphic sites gave rise to 9 YAP-DYS19 combination haplotypes in Pakistani populations, including YAP+ haplotypes 4-A, 4-B, 5-C, and 5-E. We hypothesize that the geographic distributions of YAP+ haplotypes 4 and 5 trace separate migratory routes to Pakistan: YAP+ haplotype 5 may have entered Pakistan from the Arabian Peninsula by means of migrations across the Gulf of Oman, whereas males possessing YAP+ haplotype 4 may have traveled over land from the Middle East. These inferences are consistent with ethnohistorical data suggesting that Pakistan's ethnic groups have been influenced by migrations from both African and Levantine source populations.

A polymorphic L1 retroposon insertion in the centromere of the human Y chromosome.

We have identified a novel polymorphic L1 retroposon insertion, designated LY1, in the centromeric alphoid array of the human Y chromosome. The element belongs to the transpositionally active Ta subset and its presence is compatible with normal centromere function. It was found at highest frequency in China, where it accounts for 23% of the Han sample, and was present at low frequencies in the surrounding areas, but was not found at all outside Asia. Chromosomes carrying LY1 show considerable microsatellite diversity, suggesting an ancient origin for the lineage at approximately 10 000 years ago (with wide confidence limits), but only limited subsequent migration.