This leads to reduced muscle development and reduced muscle contraction. Symptoms that manifest in the GI tract are likely to be a consequence of both reduced absorption of fats and physiological stress imposed on enterocytes that can not shuttle fats into circulation . Additional symptoms that occur throughout the body can be attributed to the lack of sufficient lipid sources. Chronic Malabsorptive Diarrhea- Diarrhea that results from the poor absorption of fats
Steatorrhea- Abnormal stools, often foul smelling, due to the increased presence of undigested fats
Vomiting
Vitamin E Deficiency- Low levels of Vitamin E due to the malabsorption of fats in the diet, causes poor brain, muscle, and eye development. Cardiomyopathy- A class of disease that affects heart muscle, causing shortness of breath, tiredness, and swelling of the legs
Slowed Growth
Failure to Thrive- Insufficient weight gain, or drastic levels of weight loss in children
Hypocholesterolemia- Low blood cholesterol levels
Hepatic Steatosis (Fatty Liver)- Excessive fat buildup in the liver, a result of the abnormal lipid panels of CMRD patients
Hyporeflexia- Absent or low levels of muscle reflexes
Amyotrophy- Muscle tissue “wasting,” the loss of muscle tissue

Diagnosis
There is no medical consensus on methodology of diagnosis for CMRD itself. There are, however, protocols used to diagnose the family of genetic disorders to which CMRD belongs. Assessment of hypobetalipoproteinemia relies chiefly on blood lipid analysis following a 12-hr fasting period. Lipids analyzed are LDL (low-density lipoproteins), triglyceride, and apolipoprotein B levels. A patient could be diagnosed with CMRD should they lack sufficient apolipoprotein B levels in the blood.
The Sar1B gene is located at position 5q31.1 in the fifth chromosome and is composed of eight exons. Alternative splicing of the second exon results into two different splice isoforms for the Sar1B transcript RNA. In CMRD, a mutation of this genomic sequence affects the Sar1B enzymes ability to interact with Guanine Exchange Factors (GEFs) and GTP-Activating Proteins (GAPs). The mutation of exon 6 of the sequence can eliminate the critical chain that is responsible for recognizing guanine. This strips the GTPase of its capability to hydrolyze GTP, its hallmark trait. This overall affects the ability of Sar1B GTPase to control chylomicron release. A third mutant allele containing a missense mutation has also been reported to cause CMRD. All three of these alleles display recessive inheritance, suggesting that they loss-of-function mutations cause the symptoms of CMRD. Physiology
During digestion, fats, or triglycerides(TGs), are enzymatically catabolized by lipases into two fatty acids and a monoglyceride molecule. Those components are then transported across the enterocyte membrane as micelles and reformed into triglycerides once across the membrane.Once transported to the ER the triglycerides are incorporated into pre-chylomicrons which are made up of TGs, cholesterol, and phospholipids. The pre-chylomicrons are then packaged into PCTV in order to be transported to the Golgi apparatus for additional maturation prior to exocytosis into the lymphatic system. From the lymphatic system, they enter general circulation, where they are produced in various forms that can be absorbed by bodily tissues and metabolized or stored by adipose tissue.