Congenital muscular dystrophies (CMDs) are a group of rare muscle disorders characterized by early onset hypotonia and motor developmental delay associated with brain malformations with or without eye anomalies in the most severe cases. In this study, we aimed to uncover the genetic basis of severe CMD in Egypt and to determine the efficacy of whole exome sequencing (WES)-based genetic diagnosis in this population. We recruited twelve individuals from eleven families with a clinical diagnosis of CMD with brain malformations that fell into two groups: seven patients with suspected dystroglycanopathy and five patients with suspected merosin-deficient CMD. WES was analyzed by variant filtering using multiple approaches including splicing and copy number variant (CNV) analysis. We identified likely pathogenic variants in FKRP in two cases and variants in POMT1, POMK, and B3GALNT2 in three individuals. All individuals with merosin-deficient CMD had truncating variants in LAMA2. Further analysis in one of the two unsolved cases showed a homozygous protein-truncating variant in Feline Leukemia Virus subgroup C Receptor 1 (FLVCR1). FLVCR1 loss of function has never been previously reported. Yet, loss of function of its paralog, FLVCR2, causes lethal hydranencephaly-hydrocephaly syndrome (Fowler Syndrome) which should be considered in the differential diagnosis for dystroglycanopathy. Overall, we reached a diagnostic rate of 86% (6/7) for dystroglycanopathies and 100% (5/5) for merosinopathy. In conclusion, our results provide further evidence that WES is an important diagnostic method in CMD in developing countries to improve the diagnostic rate, management plan, and genetic counseling for these disorders.
Brain , Exome Sequencing , Muscular Dystrophies , N-Acetylglucosaminyltransferases , Humans , Male , Egypt , Female , Muscular Dystrophies/genetics , Muscular Dystrophies/diagnosis , Child, Preschool , Brain/abnormalities , Brain/pathology , Child , Infant , Laminin/genetics , Receptors, Virus/genetics , Mannosyltransferases/genetics , Pedigree , Pentosyltransferases/genetics , DNA Copy Number Variations , Mutation , Adolescent , Nervous System Malformations/genetics
We report a rare congenital limb defect with combined features of both fibular aplasia, tibial campomelia, and oligosyndactyly (FATCO) and Fuhrmann's syndromes. A female newborn infant, born to nonconsanguineous Egyptian parents, presented with isolated abnormalities of the lower limbs comprising bilateral shortening and anterior bowing of the lower limbs at the distal third of the tibia and split foot. Radiographic examination revealed complete absence of both fibulae, anterolateral bowing and shortening of the tibia, bowing of the femora, and absence of several metatarsal and phalangeal bones. The upper limbs were clinically and radiologically normal, and the infant had neither facial dysmorphism nor other associated visceral anomalies. The presented case highlights an extremely rare limb deficiency syndrome, and together with additional case reports, it could be useful to further delineate this condition.
