SNP Shot: Genomic Insights

Hereditary fibrosing poikiloderma with tendon contractures, myopathy, and pulmonary fibrosis (POIKTMP) is a multi-system disorder affecting the skin, muscles, lungs, and pancreas. The specific signs and symptoms of POIKTMP vary from person to person.

Individuals with POIKTMP often display poikiloderma, a combination of patchy skin discoloration and telangiectases (small clusters of visible blood vessels) beneath the skin. These skin changes typically start in infancy, primarily on the face. Other possible skin findings include red, scaly patches, mild swelling (lymphedema) in the arms and legs, thickened skin on the palms and soles (palmoplantar keratoderma), and hardening (sclerosis) of tissues in the fingers and toes. Sparse scalp hair is common, and eyelashes and eyebrows may be sparse or absent. A decreased ability to sweat (hypohidrosis) can also occur, reducing heat tolerance.

Reduced joint movement (contractures), caused by the shortening of tendons, typically develops during childhood in those with POIKTMP. Calf contractures are common, leading to valgus deformity (turning in) of the feet. Elbow and wrist contractures may also occur. Muscle weakness (myopathy) in the arms and legs is also characteristic, and medical imaging often reveals abnormal fatty tissue in the muscles.

Pulmonary fibrosis, a condition where scar tissue forms in the lungs, can develop in adults with POIKTMP. This leads to breathing difficulties and can become life-threatening within a few years of symptom onset.

Beyond the skin, muscle, and lung issues described in the condition's name, POIKTMP can also involve a deficiency of pancreatic enzymes necessary for fat digestion. This enzyme deficiency can result in diarrhea and impaired absorption of fats and fat-soluble vitamins. Liver problems, short stature, and delayed puberty are also possible. Notably, intellectual development is not affected by POIKTMP.

Inheritance:

POIKTMP follows an autosomal dominant inheritance pattern. This means that only one copy of the mutated gene in each cell is enough to cause the disorder. Approximately half of affected individuals inherit the mutation from a parent who also has POIKTMP. The remaining cases arise from new gene mutations in individuals with no family history of the condition.