Regex pattern in c#

using System;

using System.Text.RegularExpressions;

class Program

{

   static void Main()

   {

      string passage = 

@"Sphingolipids are normally degraded by lysosomal enzymes. If these enzymes are deficient, partially degraded sphingolipids accumulate in cells, compromising cell function. Death may result. An a-galactosidase is deficient in Fabry's disease, a ß-glucosidase in Gaucher's disease, a sphingomyelinase in Neimann-Pick disease, and a hexosaminidase in Tay-Sachs disease. These diseases are known as thesphingolipidoses, organgliosidoses.Tay sach disease is so injurious.Taysach may be harmful.";

     // find hyphenated words

     string regExp = @"\b([a-zA-Z]+)-([a-zA-Z]+)\b";

     MatchCollection mc = Regex.Matches(passage, regExp);

     foreach(Match m in mc) Console.WriteLine(m.Value);

     Console.WriteLine();   

 

     // now look for these words with no hyphen or a space instead of the hyphen

     // ignore final 's' or capitalization

     foreach(Match m in mc)

     {

       string postHyphen = m.Groups[2].Value;

       if (m.Groups[2].Value.EndsWith("s"))

       {

          postHyphen = postHyphen.Substring(0, postHyphen.Length - 1) + @"s?";

       }

       string regExp2 = @"(?i)\b" + m.Groups[1] + @"\s*" + postHyphen + @"\b";

       MatchCollection mc2 = Regex.Matches(passage, regExp2);

       foreach(Match m2 in mc2) Console.WriteLine(m2.Value);

     }

     Console.ReadKey();

  }

}