In time, the clear layers of the cornea become clouded and retinas may begin to degenerate. Carpal tunnel syndrome (or similar compression of nerves elsewhere in the body) and restricted joint movement are common.Affected children may be quite large at birth and appear normal but may have inguinal (in the groin) or umbilical (where the umbilical cord passes through the abdomen) hernias. Growth in height may be faster than normal but begins to slow before the end of the first year and often ends around age 3. Many children develop a short body trunk and a maximum stature of less than 4 feet. Distinct facial features (including flat face, depressed nasal bridge, and bulging forehead) become more evident in the second year. By age 2, the ribs have widened and are oar-shaped. The liver, spleen, and heart are often enlarged. Children may experience noisy breathing and recurring upper respiratory tract and ear infections. Feeding may be difficult for some children, and many experience periodic bowel problems. Children with Hurler syndrome often die before age 10 from obstructive airway disease, respiratory infections, and cardiac complications.MPS I S, Scheie syndrome, is the mildest form of MPS I. Symptoms generally begin to appear after age 5, with diagnosis most commonly made after age 10. Children with Scheie syndrome have normal intelligence or may have mild learning disabilities; some may have psychiatric problems. Glaucoma, retinal degeneration, and clouded corneas may significantly impair vision.
The deep tendon reflex is also lost in patients with DSMA1.Uterine growth retardation and poor foetal movement have been observed in severe DSMA1 cases. Causes
DSMA1 is caused by a genetic mutation in the IGHMBP2 gene (located on chromosome 11, locus 11q13.3), which codes the immunoglobulin helicase μ-binding protein 2. The role of the IGHMBP2 protein is not fully understood, but it is known to affect mRNA processing. The cellular mechanisms of the mutation, as well as the protein mechanisms disrupted by the mutation, are unknown. IGHMBP2 mutations are usually random mutations which are normally not passed down through generations. Pathophysiology
The pathology underlying the observable characteristics of DSMA1 is cell body degeneration of motor nerves. Specifically, the anterior horn α-motorneurons degenerate within the first six months of life leading to a variety of symptoms. Muscle deterioration increases at around 1–2 years of age, resulting in reduced motor function. The most severely affected muscles include facial muscles and the tongue (which may develop a twitch due to hypoglossal nerve paralysis). Reduced pain sensation and excessive sweating are sometimes observed. Non-ambulant patients may develop pressure ulcers, severe constipation, urinary incontinence, and (rarely) reflux nephropathy in the advanced stages of the disease. Diagnosis
The diagnosis for DMSA1 is usually masked by a diagnosis for a respiratory disorder. In infants, DMSAI is usually the cause of acute respiratory insufficiency in the first 6 months of life. The respiratory distress should be confirmed as diaphragmatic palsy by fluoroscopy or by electromyography.