What conditions are they looking for with microarray analysis of an infant?

Question

I thought they had to be looking for something to find anything. How can they just do this test and know what to find?

He was diagnosed with achondroplasia in utero & was born 5 weeks early with physical evidence of the condition, but genetic testing revealed he does not have this or hypochondroplasia. We have just assumed that he is just small. He is 4 months old - 15 1/2 lbs. 24 in long, but his head circumference is 46 cm. He has macrocephaly & the back of his head goes out far (it looks really weird). He has portwine stains on his whole nose & filtrum with a puzzle-like pattern around his forehead, which is only noticeable when he is angry. He acquired necrelizing enterecolitis when he was 2 weeks old & was in the hospital for 2 1/2 months, where he was on TPN for 2 weeks. 2 picc lines inserted, which made him develop a DVT & 2 superficial blood clots. Loveonx was started & then his hemoglobin count dropped to a 6 & received a blood transfusion, which took it up to an 8 (which has been fluctuating since he was released). He sweats and wheezes all the time & we do labs every other week.

Answer 1

Microarray analysis looks at the expression of many genes (thousands) and compares it to a control tissue. Unless you tell me what symptoms the baby has and what tissue is being used for analysis I can't tell you what they are looking for specifically. Over or under-expression of certain genes is found in some genetic disorders.