Harvard:Biophysics 101/2007/Notebook:Kaull/2007-5-3

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OMIM workaround - in its final, nicely documented form.

Previous version has been redirected to previous day's page, in case it's still needed.

Specs are the same:

  • Accepts rs ID#
  • Returns AllelicVariant struct with name, mutation, and description parameters
from Bio import SeqIO
from Bio.Blast import NCBIWWW
from Bio.EUtils import DBIdsClient

from xml.dom import minidom
from xml.dom.minidom import parse, parseString
from threading import Thread

import pickle, sys, time, urllib

#########################################
#### Code taken from elsewhere, unedited

outputlist = []

# C-style struct to pass parameters
class AllelicVariant:
	pass

# basic text extraction from XML; based on http://docs.python.org/lib/dom-example.html
def get_text(node_list):
    rc = ""
    for node in node_list:
        if node.nodeType == node.TEXT_NODE:
            rc = rc + node.data
    return rc

def get_any_data(node):
    return node.toxml().split('>')[1].split('<')[0]

# queries the database and returns all info in an XML format
def omim_snp_search(dnsnp_id):
	client = DBIdsClient.DBIdsClient()
	query = client.search(dnsnp_id, "omim")
	records = [i.efetch(rettype="xml") for i in query]
	return records

#########################################
#### Code taken from elsewhere, edited

## Note: This is different from earlier versions!
#  shell / helper function, replaces earlier function with one parameter
#  uses XML record from OMIM, and corresponding SNP, to create AllelicVariant struct
def extract_allelic_variant_data(records, snp_id, record_type):
    if record_type == 'old':
        return extract_omim_data_old(records)
    if record_type == 'new':
        return extract_omim_data_new(records, snp_id)

    return "Incorrect type in function extract_allelic_variant_data"


#########################################
#### New code - from Kay

## Note: This code is a temporary solution to a dbSNP formatting issue.
## Older entries are best searched directly by ID #.
##  - > this case is the first covered
## Newer entries are not indexed in this fashion, although SNP ID data is
##  available on the individual entry.  These contain Allelic Variant data
##  which is located and extracted by the script
##  - > this case is the second covered


## **** TEST DATA **** (enable for testing! then delete me!)
#snp_id = 'rs11200638'
#snp_id = 'rs28937310'


## **** SUPPORT FOR NEW-STYLE PARSER ****

# queries the SNP database and returns the annotation tag for that region
# of the genome - a short, unique alphanumeric string
## Currently, DBIdsClient does not support snp parsing.  So it's not used.
## A future update should correct this when possible, for ease of reading.
def parse_geneID_tag(snp_id):
    SNP_URL = 'http://eutils.ncbi.nlm.nih.gov/entrez/eutils/efetch.fcgi?db=snp'
    snp_id_number = snp_id.strip('rs')
    url = SNP_URL + '&id=' + snp_id_number + '&mode=xml'
    
    dom = minidom.parse(urllib.urlopen(url))
    
    symbol_data = dom.getElementsByTagName('FxnSet_symbol')
    symbol = get_any_data(symbol_data[0])
    
    return symbol

# queries the database and returns all info in an XML format
def omim_tag_search(tag_id):
	client = DBIdsClient.DBIdsClient()
	query = client.search(tag_id, "omim")
	records = [i.efetch(rettype="xml") for i in query]
	return records


## **** OMIM DATA EXTRACTION ****
# Records are first sent to extract_allelic_variant_data, which takes
# a list of XML entries and the parse type ('old' or 'new').  This is a
# shell function, designed for later ease of replacement - its sole function
# is to funnel the records to the appropriate extract_omim_data function.

# The extract_omim_data functions return an AllelicVariant struct.
# Currently, this struct has name, mutation, and description entries.

# sends data in OMIM entry list to AllelicVariant struct
# configured for XML entries, in old format
def extract_omim_data_old(records):
    dom = parseString(records)
    variants = dom.getElementsByTagName("Mim-allelic-variant")

    parsed = []
    for v in variants:
	a = AllelicVariant() # create empty instance of struct
	# now populate the struct
	a.name = get_text(v.getElementsByTagName("Mim-allelic-variant_name")[0].childNodes)
	a.mutation = get_text(v.getElementsByTagName("Mim-allelic-variant_mutation")[0].getElementsByTagName("Mim-text_text")[0].childNodes)
	a.description = get_text(v.getElementsByTagName("Mim-allelic-variant_description")[0].getElementsByTagName("Mim-text_text")[0].childNodes)
	parsed.append(a)

    return parsed
        
# sends data in OMIM entry list to AllelicVariant struct
# configured for XML entries, in new format
def extract_omim_data_new(records, snp_id):
    dom = parseString(records)
    variants = dom.getElementsByTagName("Mim-allelic-variant")

    # convert SNP ID into number format
    snp_id = snp_id.strip('rs')
    
    parsed = []
    for v in variants:
	a = AllelicVariant() # create empty instance of struct
	# now populate the struct

	variant_snp_tag = v.getElementsByTagName("Mim-allelic-variant_snpLinks")

	# additional code checks for SNPs linked to allelic variant
	# if SNPs are present, it searches for the correct SNP - if found,
	# the variant is added to results list
	if variant_snp_tag != list():
	    isLinked = False
	    for i in variant_snp_tag:
                variant_snp = get_text(i.getElementsByTagName("Mim-link_uids")[0].childNodes)
                variant_snp = str(variant_snp)
                if variant_snp == snp_id:
                    isLinked = True

            if isLinked:
	        a.name = get_text(v.getElementsByTagName("Mim-allelic-variant_name")[0].childNodes)
	        a.mutation = get_text(v.getElementsByTagName("Mim-allelic-variant_mutation")[0].getElementsByTagName("Mim-text_text")[0].childNodes)
	        a.description = get_text(v.getElementsByTagName("Mim-allelic-variant_description")[0].getElementsByTagName("Mim-text_text")[0].childNodes)
	        parsed.append(a)
    
    return parsed


## **** MAIN FUNCTIONS ****

# takes SNP ID and gets search results from OMIM in XML format
def snp_to_omim(snp_id):
    records = omim_snp_search(snp_id)

    # if records are found, then search is complete
    # use old parser - SNP was directly in search text
    if records != list():
        return records, 'old'

    # otherwise, find geneID tag for the region, and search that
    tag_id = parse_geneID_tag(snp_id)
    records = omim_tag_search(tag_id)

    # use new parser - SNP was hidden in XML markup
    return records, 'new'


# takes list of XML records from OMIM, and the corresponding SNP ID
# generates desired output as a list of text entries
def omim_to_output(records, snp_id, record_type):
    output = list()
    
    if records == list():
        output.append("No information found for " + snp_id + "\n")
        return output

    for i in records:
        variants = extract_allelic_variant_data(i.read(), snp_id, record_type)
        
        if variants != None:
            for a in variants:
                output.append(a.name + "\n")
                output.append(a.mutation + "\n")
                output.append(a.description + "\n")

    return output

omim_records, record_type = snp_to_omim(snp_id)
output_list = omim_to_output(omim_records, snp_id, record_type)

for item in output_list:
        print item
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