Whole exome sequencing identifies LRP1 as a pathogenic gene in autosomal recessive keratosis pilaris atrophicans.

BACKGROUND: Keratosis pilaris atrophicans (KPA) is a group of rare genodermatoses characterised by perifollicular keratosis and inflammation that progresses to atrophy and scars of the facial skin. Keratosis pilaris of extensor areas of limbs is a common associated finding. Most cases with KPA are sporadic and no consistent inheritance pattern has been documented. METHODS: A large consanguineous Pakistani pedigree segregating autosomal recessive KPA of a mixed type was subject to autozygosity mapping and whole exome sequencing. Quantification of mRNA and protein levels was performed on fibroblasts from affected individuals. Cellular uptake of the low-density lipoprotein (LDL) receptor-related protein 1 (LRP1) ligand α2-macroglobulin (α(2)M) was quantified using fluorescence confocal microscopy. RESULTS: Genetic analyses identified a unique homozygous missense variant (K1245R) in the LRP1 in all affected family members. LRP1 encodes the LRP1, a multifunctional cell surface receptor with endocytic functions that belongs to the LDL receptor family. The LRP1 mRNA and LRP1 protein levels in fibroblasts of affected individuals were markedly reduced when compared with controls. Similarly, the LRP1-mediated cellular uptake of α(2)M was reduced in patient fibroblasts. CONCLUSIONS: This is the first report on LRP1 as a pathogenic gene for autosomal recessive KPA and keratosis pilaris. The inflammatory characteristics of the KPA entity in our family suggest a link to the immune-regulatory functions of LRP1.

ß-Thalassemia in Pakistan: a pilot program on prenatal diagnosis in Multan.

Prenatal diagnosis (PND) of ß-thalassemia has been underutilized in Pakistan because of a number of social and economic factors. National Institute for Biotechnology and Genetic Engineering Faisalabad in collaboration with Multan Institute of Nuclear Medicine and Radiotherapy Multan introduced free PND service for carrier couples of Multan district. Multan has a population of about 4 million. More than 170 couples registered for retrospective PND and in 2 years 105 PND were carried out through first trimester chorionic villus sampling. Almost 90% of these couples were unable to afford the cost of PND and would not have undergone the test as free service was not available. Monoplex and Multiplex Amplification Refractory Mutation System-polymerase chain reaction and genomic DNA sequencing were used for detection of IVS (intervening sequence)-I-5 (G-C), FSC (frameshift codon)-8/9 (+G), FSC-41/42 (-TTCT), IVS-I-1 (G-T), 619 bp deletion, and CD-15 (G-A) ß-globin mutations. Eighty-one percent (85/105) couples analyzed were in a consanguineous marriage. Twenty-three fetuses were found homozygous mutant and all couples opted for discontinuation of affected pregnancies. More families are registering for PND after establishment of this free and accessible PND service.

Spectrum of beta-thalassemia mutations in various regions of Punjab and Islamabad, Pakistan: establishment of prenatal diagnosis.

We present here an analysis of 888 unrelated beta-thal chromosomes consisting of 444 transfusion dependent children from various regions of Punjab and Islamabad Pakistan. By using Multiplex ARMS- PCR, restriction endonuclease analysis, allele specific oligonucleotide (ASO) hybridization and sequencing, 17 beta-thal mutations and 3 Hb variants were detected in 99.5 % (884/888) of the chromosomes analyzed. First trimester prenatal diagnosis by chorionic villus sampling (CVS) was also carried out in seven pregnancies at risk of beta-thalassemia. Our results indicate that three most common mutations accounted for 86.8% of the beta-thal alleles in this region. These findings have important implications for prevention of beta-thalassemia through genetic counseling and prenatal diagnosis in this part of Pakistan.