Diagnostic Odyssey and Application of Targeted Exome Sequencing in the Investigation of Recurrent Infant Deaths in a Syrian Consanguineous Family: a Case of Spinal Muscular Atrophy with Respiratory Distress Type 1

Spinal muscular atrophy with respiratory distress type 1 (SMARD1) is a rare autosomal recessive disorder caused by a defect in the immunoglobulin mu binding protein 2 (IGHMBP2) gene, leading to motor neuron degeneration. We identified an infant with SMARD1 by targeted exome sequencing from a consanguineous Syrian family having a history of recurrent infant deaths. The patient initially presented intrauterine growth retardation, poor sucking, failure to thrive, and respiratory failure at the age of two months, and an inborn error of metabolism was suspected at first. Over a period of one month, the infant showed rapid progression of distal muscular weakness with hand and foot contractures, which were suggestive of neuromuscular disease. Using targeted exome sequencing, the mutation in IGHMBP2 was confirmed, although the first report was normal. Targeted exome sequencing enabled identification of the genetic cause of recurrent mysterious deaths in the consanguineous family. Additionally, it is suggested that a detailed phenotypic description and communication between bioinformaticians and clinicians is important to reduce false negative results in exome sequencing.

Progress of Spinal muscular atrophy with respiratory distress type 1 / 中华实用儿科临床杂志

Spinal muscular atrophy with respiratory distress type 1 (SMARD1) is a rare autosomal recessive neuromuscular disease.It is caused by mutations in the gene immunoglobulin μ-binding protein 2 which resides on chromosome 11 q13.3 and encodes the immunoglobulin μ-binding protein 2.This disorder is characterized by degeneration of anterior horn α-motoneurons and manifesting as irreversible diaphragmatic paralysis,respiratory distress associated with progressive symmetrical muscular weakness,distal lower limbs mainly involved,and muscle atrophy between the first 6 weeks and 6 months of life.Overall,SMARD1 is a poor-prognosis disease that artificial ventilation is needed for the whole life.